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A review and research trends in alternate frying technologies
Abstract
Deep-fat frying is a century-old process which is still being used for preparation of various food products in our regular diet. Increase in the consumer health awareness has motivated more research in development of healthy and safe fried products. Recent strategies to attain this goal have been focused on reduction in oil uptake by fried products and increasing the stability of frying medium. Another approach includes development of alternative frying technologies such as pressure frying, microwave frying, vacuum frying and radiant frying or their combinations. Among all the alternative frying technologies, only vacuum frying have shown acceptance and commercial utilization by the food industries. Pressure frying and radiant frying have also shown some promising potential, but need further exploration.
... Therefore, it is crucial to find ways to improve the oxidative stability of oils used in frying. Some strategies adopted by the Food Industry include enriching frying oils with compounds with potential antioxidant activity (Márquez-Ruiz et al., 2014), as well as exploring alternative frying techniques, such as pressure, microwave, radiant and vacuum frying, among others (Pankaj & Keener, 2017;Devi et al., 2021). However, to date, only vacuum frying has gained acceptance and has been used commercially by the food industries (Pankaj & Keener, 2017). ...
... Some strategies adopted by the Food Industry include enriching frying oils with compounds with potential antioxidant activity (Márquez-Ruiz et al., 2014), as well as exploring alternative frying techniques, such as pressure, microwave, radiant and vacuum frying, among others (Pankaj & Keener, 2017;Devi et al., 2021). However, to date, only vacuum frying has gained acceptance and has been used commercially by the food industries (Pankaj & Keener, 2017). In this technique, the application of pressure below atmospheric levels reduces the boiling point of water, thus minimising the frying temperature of the oil (Manzoor et al., 2022;Pankaj & Keener, 2017). ...
... However, to date, only vacuum frying has gained acceptance and has been used commercially by the food industries (Pankaj & Keener, 2017). In this technique, the application of pressure below atmospheric levels reduces the boiling point of water, thus minimising the frying temperature of the oil (Manzoor et al., 2022;Pankaj & Keener, 2017). The combination of the lower temperature and the lower amount of oxygen during vacuum frying improves the quality characteristics of fried foods and could contribute to improved oxidative stability of oils. ...
... A pesar de estas desventajas, los tratamientos térmicos siguen siendo ampliamente utilizados debido a su efectividad y menor costo de implementación en comparación con las tecnologías no térmicas emergentes. Los tratamientos no térmicos, aunque ofrecen ventajas en términos de retención de nutrientes, suelen ser más costosos debido a la inversión inicial en equipos especializados y los desafíos asociados con su implementación a escala industrial [37,38,39]. ...
... Así pues, estos tratamientos demuestran que permiten la inactivación de enzimas como el polifenol oxidasa y la peroxidasa en diversos productos [14,47]. Sin embargo, como señalan investigadores de diversos países, la eficacia de estos tratamientos puede variar según el tipo de alimento y las condiciones específicas de procesamiento, por lo que se necesita más investigación para optimizar su aplicación en diferentes matrices alimentarias [37,38,39]. Además, es importante considerar la integración de estas tecnologías no térmicas con otros métodos de procesamiento para maximizar sus beneficios y superar sus limitaciones individuales [15,16,27]. ...
... Sin embargo, es importante advertir que la viabilidad de estas tecnologías debe considerarse en un contexto más amplio, teniendo en cuenta los costos iniciales de inversión más altos [38]. No obstante, se ha indicado que estos costos pueden compensarse con el tiempo debido a la mayor eficiencia energética y la menor pérdida de producto [39]. ...
... Fried food has become a popular snack option due to its widespread consumption. To meet consumers' daily life requirements, manufacturers produce high-quality fruits and vegetable-based snacks (Pankaj & Keener, 2017). Researchers continuously strive to enhance fried food's efficiency by improving frying technology and ingredients. ...
... Aside from deep-fat frying, other strategies to reduce oil consumption have been adopted. There are significant differences between frying methods when it comes to minimizing oil uptake and preserving the textural and olfactory properties of fried foods (Pankaj & Keener, 2017). ...
... Due to this, microwave frying has been limited in its application as a standalone technology . It is important to develop microwave frying systems that are uniform enough for adapting different ingredients, such as different shapes and sizes, as well as their initial temperatures (Pankaj & Keener, 2017). As a result, by reducing the frying time with microwave frying, acrylamide is formed, resulting in a darker product. ...
Frying is one of the most popular and traditional processes used in the food industry and food services to manufacture products that are high in quality and with unique sensory characteristics. The most common method of frying is deep-fat frying, used worldwide due to its distinct flavor profile and sensory aspects, which leads to physio-chemical changes at both macro and micro levels. One of the major concerns with deep-fried foods is their high oil content, and a variety of metabolic disorders can be caused by overconsumption of these foods, including heart disease, obesity, and high cholesterol. Due to their enticing organoleptic properties with their delicious flavor, pleasing mouthfeel, and unique taste, making them irresistible, it is also responsible for undesirable and unacceptable characteristics for consumers. Oil absorption can be reduced by developing novel frying methods that limit the amount of oil in products, producing products with fewer calories and oil while maintaining similar quality, flavor, and edibility. In addition, different pretreatments and post-frying treatments are applied to achieve a synergistic effect. The transfer of mass and heat occurs simultaneously during frying, which helps to understand the mechanism of oil absorption in fried food. Researchers have discovered that prolonged heating of oils results in polar compounds such as polymers, dimers, free fatty acids, and acrylamide, which can alter metabolism and cause cancer. To reduce the oil content in fried food, innovative frying methods have been developed without compromising its quality which also has improved their effect on human health, product quality, and energy efficiency. The aim is to replace the conventional frying process with novel frying methods that offer fried food-like properties, higher nutritional value, and ease of use by replacing the conventional frying process. In the future, it might be possible to optimize frying technologies to substantially reduce fried foods' oil content. This review focuses on a detailed understanding of different frying techniques and attempts to focus on innovative frying techniques such as vacuum frying, microwave cooking, and hot-air frying that have shown a better potential to be used as an alternative to traditional frying.
... Frying is classified as a dry heat cooking method that is widely used at both domestic or industrial levels. The mechanism of frying can be described in four-stage which are the heat up stage, surface boiling stage, falling rate stage and bubble end point stage (Pankaj and Keener, 2017). The heat-up stage occurs when the food is immersed in the oil until the temperature of the surfaces reaches the boiling point of water. ...
... This condition is categorized as the surface boiling stage where the heat transfer coefficient increases by conductive (heat transfer within food) heating and free convective (heat transfer from the oil to the food eISSN: 2550-2166 © 2022 The Authors. Published by Rynnye Lyan Resources REVIEW surface) (Pankaj and Keener, 2017). The increasing heat transfer rate between oil and air leads to an increase in the oxidative degradation of oil (Gertz, 2014). ...
... The food enters the bubble end point stage, where the water vaporization is closed to the end. The condition during the last stage of the frying mechanism is caused by several factors such as the reduction in heat transfer to the crust or core interface or the complete removal of water inside the food (Pankaj and Keener, 2017). ...
Fish and fish products contain important source of nutrient that provides benefits upon consumption. The increasing demand and high utilization of fish have caused a market shift in the fishery industry. Although fish is nutritious, some consumers do not prefer to consume fish in its original form because of its fishy taste, fishy odour and it is highly perishable. To further promote the consumption of fish, the production of fish products and frying are applied to suit consumers’ preferences. Frying is commonly used in various food premises as it changes the characteristics of the fish and fish products, especially the taste and texture. However, the increase in awareness has changed the perception of the consumer as they prefer healthier food in their lifestyle. Despite the increase in awareness, some consumers still prefer fried foods and food products due to their unique sensory properties and texture. To understand the effects of frying on foods, several parameters during frying are studied. Frying temperature, frying cycle, frying time, frying techniques and frying oils used are parameters that could affect the physicochemical and sensory attributes of the fish and fish products. Repetitive frying could cause the formation of toxins and alter the fatty acid content in the fish, fish products and frying oils. This changes the taste and alters the composition of the foods. Meanwhile, different frying times, oil and techniques cause significant changes to the chemical composition, sensory attributes, lipid oxidation, fat content, oil absorption and fatty acid profiles of the fish and fish product. This review aimed to gather information specifically on the changes in fish and fish products upon frying at different frying cycles, time, temperature, oils, and techniques.
... MWF results in higher thermal efficiency, shorter drying time, and better final quality compared to CF. However, further studies are required to understand the mechanism and interaction of these technologies with different food matrices (Pankaj & Keener, 2017). Exploring and optimizing these technologies can lead to the production of healthier and safer fried products. ...
... Exploring and optimizing these technologies can lead to the production of healthier and safer fried products. For example, nonuniform heating and oil deterioration at high temperatures are the main challenges of MWF (Pankaj & Keener, 2017). However, these challenges can be overcome by using proper equipment and operating conditions. ...
Frying is a popular cooking method that produces delicious and crispy foods but can also lead to oil degradation and the formation of health‐detrimental compounds in the dishes. Chemical reactions such as oxidation, hydrolysis, and polymerization contribute to these changes. In this context, emerging technologies like ultrasound‐assisted frying (USF) and microwave (MW)‐assisted frying show promise in enhancing the quality and stability of frying oils and fried foods. This review examines the impact of these innovative technologies, delving into the principles of these processes, their influence on the chemical composition of oils, and their implications for the overall quality of fried food products with a focus on reducing oil degradation and enhancing the nutritional and sensory properties of the fried food. Additionally, the article initially addresses the various reactions occurring in oils during the frying process and their influencing factors. The advantages and challenges of USF and MW‐assisted frying are also highlighted in comparison to traditional frying methods, demonstrating how these innovative techniques have the potential to improve the quality and stability of oils and fried foods.
... It typically entails submerging food items in hot oil within a temperature range of 150-190°C under normal atmospheric conditions. Although this method and its resulting products enjoy popularity, there are several notable drawbacks associated with frying and fried foods (Pankaj & Keener, 2017). Deep-fat frying involves complex oil absorption influenced by various factors, leading to structural, chemical and physical changes in both the oil and the food, necessitating careful control over absorption quantity and quality (Asokapandian et al., 2019). ...
... They are recognising the dangers of consuming energy-rich but nutritionally deficient food items and are looking for alternatives to traditional frying methods that have been used for centuries. This highlights the need to explore innovative approaches (Pankaj & Keener, 2017). The main goal is to improve the frying process by reducing and controlling the fat content of the fried items. ...
Contemporary dining habits have spurred a shift in ready‐to‐eat (RTE) snack production, with mushrooms offering a nutritional boost due to their protein, carbohydrate, fibre and vitamin content. Proximate composition data aid in creating snacks with balanced nutrition. Mushrooms also contribute antioxidants and antimicrobial compounds, adding a health dimension. Extrusion cooking, known for adaptability and energy efficiency, improves texture, nutrition and shelf life. Though concerns exist about oil intake, frying remains popular for taste and consistency enhancement, requiring careful management. Baking extends shelf life and preserves flavour while enhancing nutrient availability. Various studies highlight the potential of these techniques to meet consumer preferences for convenient, appealing and health‐conscious snacks by incorporating ingredients like legume protein isolates, nuts and seeds, etc. The RTE snack industry evolves to provide healthier options driven by technological innovations and sustainability practices, with personalised and functional snacks on the horizon. The study aims to explore and highlight the nutritional benefits of incorporating mushrooms into RTE snacks and discusses the unique advantages of extrusion, frying and baking in snack production.
... The global trend towards the consumption of healthy foods has promoted the development of alternative cooking techniques that can maintain and improve the quality of fried foods. Therefore, novel frying technologies have emerged as alternatives to traditional deep-fat frying, such as microwave, vacuum spray, radiant frying, and hot air frying technologies [7,31,47,51]. These approaches have gained interest in the industry and among consumers looking for relatively healthy fried products. ...
... Frying technology is widely used in homes, restaurants, and industries [31,50]. Traditionally, foods are deep-fried with fats or oils (Abd [1]). ...
Hot air frying is a relatively new technique used to produce fried food. The aim of this review is to understand the influence of this approach on food quality. Based on the existing research in the literature, a range of findings have emerged regarding changes in textural properties and decreases in moisture content. These outcomes are associated with variations in frying time and temperature parameters. Furthermore, as the duration and temperature of the process increase, lightness decreases, and compared to the traditional frying method, foods exhibit satisfactory sensory characteristics after hot air frying. This technique offers advantages in reducing oil use and the development of relatively few acrylamides during the process. Additional studies evaluating the
microstructure are necessary using other techniques, such as transmission electron microscopy and atomic force microscopy. Moreover, future research should be focused on optimizing the process and studying other foods. As a critical process in the food industry, hot air frying directly affects food quality and influences the microstructure. An inadequate frying process can result in unpleasant food for the consumer; thus, process optimization and sensory attributes of the food are addressed. This work provides essential information about advances in food quality using hot air frying.
... Frying, microwaving, baking, steaming, and drying are common cooking methods for shrimp [2]. Fried shrimp are popular among consumers due to their unique flavor and texture derived from physicochemical reactions during frying [3,4]. However, these reactions also destroy the nutrients in the fried shrimps, resulting in the oxidative loss of protein, polyunsaturated fatty acids, and astaxanthin [2,5]. ...
... Thus, SSE had a higher protein content than that the other samples, while WS had the lowest protein content. It was suggested that water evaporation provides void spaces for oil absorption [4], and frying oil enters the interior of fried foods through tiny pores under pressure [30]. Therefore, water loss is usually accompanied by oil absorption during frying, which is one of the reasons SSE had a higher oil content and lower water content than SS, and WS had the highest water content and oil absorption. ...
Fried shrimp are popular for their attractive organoleptic and nutritional qualities. However, consumers are more concerned about the safety of fried foods. To investigate the formation of advanced glycation end products (AGEs) in fried shrimp and provide pretreatment guidance for producing low-AGEs fried pacific white shrimp were treated with seven pretreatment methods before frying. The AGEs contents, physicochemical indicators, and their correlations in the fried shrimps’ interior, surface, and batter layer were analyzed. Results indicated that pretreatment methods influenced both Maillard and oxidation reactions by altering the basic compositions, which controlled the formation of AGEs. The highest and lowest AGEs contents were obtained in shelled shrimp with exscinded back and whole shrimp, respectively. The batter-coated treatment reduced the AGEs contents in samples but increased the oil content. Correlation analysis showed that lipid oxidation was the decisive chemical reaction to the formation of AGEs by promoting the generation of dicarbonyl compounds and their combination with free amino acids. Conclusively, the whole shrimp was suitable for producing fried shrimp with low AGEs, oil content, and desirable color.
... Among these techniques, the popularity of vacuum-fried food is emerging due to the enormous advantages conferred by it. VF holds a great potential in producing safe and nutritious foods as it is operated under low temperature and in the absence of oxygen, establishing a firm foundation to replace traditional ones soon (Pankaj & Keener, 2017). This technique is better than traditional as it reduces time of frying and utilizes less temperatures thereby produces a quality and safe foods. ...
... MWs (0.3-300 GHz) possess the property of reacting directly with polar water molecules and charged ions in a rapidly rotating electromagnetic field. This results in dipole rotation or ionic polarization creating molecular vibrations which in turn heat the materials in less time and with uniform heat transfer (Pankaj & Keener, 2017). Thus, MVFs have the potential to reduce heating time and oil content on the food surface and achieve better texture, color, and flavor of food than VF alone. ...
Vacuum frying has proven to be the most feasible technique to obtain safe and nutritious deep‐fried food without compromising its organoleptic and textural properties. This frying system has a lot of benefits over conventional frying such as reduced acrylamide content, lower oil content and better preservation of nutritious compounds. The most promising advantage of vacuum frying is its ability to produce foods with a low glycemic response. Optimization of vacuum frying technology is, however, a prerequisite to attain a fried product with desirable quality. Microwave‐assisted vacuum frying, ultrasound‐assisted microwave vacuum frying, and pulse‐spouted microwave vacuum frying are some of the novel frying techniques which improve the quality of fried products with enhanced nutrient retention, reduced oil uptake, and reduced starch digestibility. In addition, various pretreatments, posttreatments, packaging, and storage conditions have a profound effect on the quality of vacuum‐fried foods. This review aims to address the advantages vacuum frying offers over conventional frying, providing an overview of recent developments in this technology, and the effects of vacuum frying on the nutritional qualities of food.
Practical Applications
Frying industry all over the world is in boom as frying provides unique flavor and texture to the food products. However, the consumption of fried foods has been related to the development of various diseases due to the generation of harmful compounds at higher temperatures employed during deep‐frying. Vacuum frying has been suggested to overcome this limitation of atmospheric frying by maintaining low‐temperature conditions, thus producing safe foods. This review will focus on the developments done in vacuum fryer over the past few years and evaluate what enhancements in final fried products can be observed upon modifying the vacuum frying unit. Replacement of atmospheric fried products with vacuum‐fried products could further boost the frying sector by producing toxin‐free products without sacrificing sensorial or organoleptic properties.
... It is also a dehydration procedure which has been widely applied in food processing industries to develop ready-to-eat snacks (Dehghannya & Ngadi, 2021;Zhang, Zhang, & Adhikari, 2020). It is a kind of complex operation including physical and chemical changes such as moisture evaporation, protein denaturation, starch gelatinization, lipid oxidation, texture modifications and so on (Pankaj & Keener, 2017;Sruthi et al., 2021;Zhang, Zhang, & Adhikari, 2020). Many frying methods have been traditionally adopted such as deep fat frying (immersion frying), pan-frying, and stir-frying where the food is immersed in edible oil and is heated above the boiling point of water (Moreira, 2014;Shaker, 2015). ...
... Some undesirable changes are chanced during these frying processes which are not often preferred as a healthy consumer's diet. (Ghaderi, Dehghannya, & Ghanbarzadeh, 2018;Pankaj & Keener, 2017). ...
Vacuum frying (VF) is known as the most popular food processing method for the production of ready-to-eat snacks. It includes simultaneous mass and heat transfer in very low temperature and frying period to provide higher qualitative products. The quantity of oil used for frying is less in the vacuum frying method as compared to other frying methods. Numbers of physical, chemical, and structural changes occur during the frying process by evaporation of moisture, obstruction of oil movement, gelatinization of starch, denaturation of protein structure, and solubilization of pectin cells. These changes lead to textural modification of fried products and VF successfully enhances the textural properties at optimum process parameters which are according to the consumers’ acceptance. In this context, this review is an update of the VF, showing the effect of different process parameters on the improvement of the texture of the fried snacks. Additionally, the mechanism behind the development of texture due to VF has been described in detail along with proper figures. Also, a comparative study of VF and atmospheric conventional frying on the increment of textural characteristics in various food materials starting from fruits and vegetables to fish and meat products have been highlighted. Moreover, to enhance the food texture during VF, several pre/post frying treatments are carried out which have been taken into discussion. Further, some novel techniques adopted along with VF, which influence highly on texture development of food materials, have been mentioned.
... Besides, given the complex phenomena undergoing during frying, this cooking technique has attracted the attention not only of consumers but also of scientists looking to explain and analyse the chemical and physical changes in the fried product, including starch gelatinisation, protein denaturation, water evaporation, crust formation, Maillard reaction, caramelisation as well as oxidation, hydrolysis and polymerisation in the frying media (Zaghi et al., 2019). However, the elevated use of lipids, which implies a high caloric intake, increased risk of developing type 2 diabetes, heart failure, obesity and hypertension, along with the adverse effects of consuming toxic compounds generated during the process, confer some disadvantages to frying over other cooking techniques (Pankaj & Keener, 2017). Consequently, in recent years, novel frying techniques have arisen to overcome these health issues and disadvantages of traditional frying without neglecting the flavour and properties of fried products; in this regard, pressure frying, microwave frying, radiant frying and vacuum frying have been the most studied alternate frying technologies (Zaghi et al., 2019). ...
... The utilisation of these technologies has yielded effective results mainly in reduced cooking time, improved texture (tenderness and juiciness) of the fried product and lowered oil absorption. Additionally, given the low temperatures employed during vacuum frying, this specific technique has been demonstrated to aid in reducing oil deterioration, product colour improvement, minor degradation of nutritional compounds, reduced acrylamide content and increased retention of bioactive compounds such as total phenolics, flavonoids and carotenoids (Pankaj & Keener, 2017). Su et al. (2018) define vacuum frying (VF) as an advanced frying technology that processes food under pressures below atmospheric levels, thus reducing the boiling points of the frying media and the water in food. ...
Vacuum frying (VF) is a process developed at a pressure lower than atmospheric pressure, in which lower temperatures are employed to remove moisture from the food and reduce the oil content in the final product. Diverse studies have been published for VF or assisted with microwave and ultrasound, facing the challenges of accomplishing the physical and sensory properties appreciated in fried products. The studied matrices under VF include mainly vegetable origin foods (apple, banana, carrot, donuts, kiwi, mushroom, pea, pear, potato and sweet potato) and some animal origin products (chicken nuggets, fish fillets and surimi products). This review aimed to show recent and relevant findings of the application of VF, analysing both the effects on the frying medium and the impact on the fried foods. The inclusion of microwave and ultrasound technologies aids in the obtention of high‐quality products in terms of sensory and textural attributes, oil content as well as reduced oil degradation. This technique may provide safer and stable fried foods with lower oil content aiding in improving the diet of consumers and reducing production costs.
... Presently microwaves are being used on both domestic and commercial scales for various functions like baking, thawing, cooking, and drying. It is the configuration of electromagnetic radiation frequency ranging from 0.3 GHz to 300 GHz with wavelengths from 1mm-1m [74]. Compare to conventional deep fryers microwaves are more beneficial in oil uptake and reduced processing time [75]. ...
Starch is a functional element in food that serves as a vitally important source of energy. In fried foods like potato chips, French fries, instant noodles, and coating flour, starch is primary ingredient. Deep frying changes the structure of foods and adds extra oil to them. When it comes to cooking and processing food, deep-fat frying is by far the most popular technique employed by consumers, eateries, and factories around the globe. Most obviously, it slashed lead times and allowed for the innovation of novel cuisine with appealing sensory properties. After being ingested, the starch and fat found in deep-fried foods are digested by enzymes in the human body, yielding glucose and fatty acids as the primary source of energy. Overconsumption of these deep-fried starchy meals, however, has been linked to an increase in body fat, obesity, and the onset of several different degenerative and cancerous conditions. Pressure frying, microwave frying, vacuum frying, radiant frying, and air frying are only a few of the alternative frying technologies that can lower the amount of processing toxicants in fried foods. In this analysis, we look at how the new frying technique has influenced the industry.
... Sunflower oil is widely regarded as one of the top choices for cooking due to its high content of essential fatty acids that promote bodily growth, as well as its abundance of fat-soluble vitamins E, D, A, and K, which act as natural antioxidants. Fats, comprising up to 40% of the total energy in food, are a significant source of energy (32). ...
A portion of edible sunflower oil obtained from the local market was obtained and split into six segments. One segment served as the control sample, while the other five segments were used for frying for a duration of five hours. At each hour, a sample was extracted for inspection. The study included conducting chemical and physical testing on all samples. Additionally, gas chromatography (GC) analysis was performed to track the concentrations of essential fatty acids (namely linoleic and linolenic acids) in four oil samples. The obtained findings are as follows: Following a duration of five hours of frying, the melting point experienced a reduction of 2°C, the specific weight underwent a change from 0.9178 to 0.9255, the viscosity exhibited a rise from 40.82 to 48.70 CBP, and the refractive index had a modest alteration, transitioning from 1.4722 to 1.4735. The chemical tests yielded the following results: the free fatty acid content did not exceed 0.6%, the smoking point was reduced from 285°C to 245°C, the peroxide number remained within the permitted range without any modification, and the acidity level met the required specifications. The levels of unsaturated fatty acids in the control sample were as follows: oleic acid decreased from 263 ppm to 0.173 ppm, linoleic acid decreased from 102 ppm to 8.784 ppm, and linolenic acid decreased from 339 ppm to 17.27 ppm. Unsaturated acids exhibit less stability throughout the course of frying. The stability of the oil is directly correlated with the duration of frying. In general, sunflower oil is considered one of the most suitable oils for frying and remains stable for up to 5 hours of frying. The oil's essential acid concentration drops as the frying time increases, in addition to its physical qualities.
... El freído por aire forzado es un método económico y se encuentran equipos de uso doméstico comercialmente disponibles a nivel mundial. En este proceso, el alimento frito se obtiene por contacto directo del producto y una emulsión externa de gotas de aceite en aire caliente dentro de una cámara que está en movimiento constante [59,60]. Imita la deshidratación y la formación de la corteza típica de los alimentos fritos de la manera convencional. ...
... Currently, there is a trend toward incorporating higher proportions of whole flour and high-fiber ingredients into various products to decrease oil absorption while increasing dietary fiber intake. Furthermore, a commonly explored approach for decreasing oil absorption involves establishing oil barriers using other batter and coating systems (Pankaj & Keener, 2017). The relationship between oil uptake and frying duration demonstrates a non-monotonic trend. ...
This review concentrates on cutting‐edge pretreatments for deep‐fat frying that are meant to lower energy costs and enhance product quality. Methods such as freezing, blanching, pulsed electric fields, superheated steam, and ultrasonication are investigated to improve flavor without increasing cooking time. The study focuses on techniques to reduce oil absorption, specifically using physicochemical changes and hydrocolloid coatings. When added before or after frying, functional ingredients such as proteins and non‐protein hydrocolloids take advantage of cooling‐phase effects and water replacement mechanisms to minimize oil absorption. Effective barrier agents that preserve the texture and moisture of fried foods like French fries include pectin, CMC, and xanthan gum. While the effectiveness of various hydrocolloids varies, carrageenan and gum Arabic are particularly effective. French fries treated with guar gum and sorbitol showed reductions in total oil between 30.6% and 50.8%, respectively. Furthermore, the initial moisture content affects physical changes that occur during frying, such as the development of porosity, which affects the absorption of oil. This thorough analysis provides insights into cutting‐edge methods for making fried foods with less oil while preserving sensory qualities. Future studies will be focused on developing novel physicochemical changes and hydrocolloid coatings that use functional ingredients such as proteins and non‐protein hydrocolloids to efficiently lower excessive oil absorption.
... This results in the formation of a uniform layer on the surface of the food, simultaneously generating substantial changes in its chemical, physical, and sensory properties (Asokapandian et al., 2020). These transformations include protein denaturation, hydrolysis, starch gelatinization, and food dehydration (Berk, 2018;Oke et al., 2018;Van Koerten et al., 2017), ultimately resulting in a reduction of its moisture content (Pankaj & Keener, 2017). Furthermore, it contributes to the formation of acrylamide in most food products (Baskar & Aiswarya, 2018). ...
During frying, oils can deteriorate due to autoxidation and hydrolytic alterations, processes influenced by the oil's fatty acid composition (FAC) and antioxidant content. However, there are different techniques to improve fried food quality and reduce oil absorption. This review aims to assess existing literature on the interactions between frying methods, oil selection, and the chemical composition of foods. To achieve this goal, the article examines the impact of oil FAC, antioxidants, pretreatments, and alternative frying technologies. A literature search was conducted from 2016 to 2023. The keywords used were (AND/OR) frying, fried foods, oil, oil absorption, and fatty acids. Oils rich in monounsaturated fatty acids and antioxidants, such as olive oil, are recommended for their nutritional benefits and improved oil stability. The water content and structure of the food also play a significant role in oil absorption. Pretreatments to diminish food moisture content contribute to a lower oil absorption in the fried food while mitigating excessive accumulation of lipid oxidation products. Proper selection of frying oils, incorporation of antioxidants, and the use of pretreatments could help prevent chemical changes and minimize oil absorption during frying. These measures contribute to maintaining the nutritional quality and safety of fried foods while also enhancing their overall sensory appeal.
... Presently microwaves are being used on both domestic and commercial scales for various functions like baking, thawing, cooking, and drying. It is the configuration of electromagnetic radiation frequency ranging from 0.3 GHz to 300 GHz with wavelengths from 1mm-1m (Pankaj & Keener, 2017). Compared to conventional deep fryers microwaves are more beneficial in oil uptake and reduced processing time (Oztop et al., 2007). ...
Thesis Pandey AK. 2020. Effects of pre-treatments and vacuum frying conditions on quality characteristics of papaya (Carica papaya L.) chips.
... According to a recent survey, it is estimated that there will be a $208 billion increase in food sales in the United States across supermarkets, restaurants, fast-food establishments, and other retail food outlets by 2020. 27 In a globalized environment where competitiveness and business growth are based on entering new markets, companies must comply with the regulations issued by each target country for their diversification. That is why in countries such as China, South Korea, and Australia, among others, factories dedicated to snack production have shown interest in developing technologies to ensure that the fried products they market meet the highest quality standards, including compliance with the acrylamide levels established by European regulations. ...
On the occasion of the 20th anniversary of the discovery of acrylamide in food, an analysis of patents related to the mitigation of this compound in food products obtained through immersion frying was carried out. For this purpose, a comprehensive search, compilation, and information analysis were conducted using free online databases such as Google Patents, Patenscope, and Lens. The search yielded a total of 79 patents within the considered time period (2002-2022). The countries with the highest number of granted patents were the United States, the European Union, and South Korea. The patents were classified into four main approaches: raw material modification (49%), application of pre-treatments (27%), process modification (16%), and measurement techniques (8%). Among the results, Frito-Lay, an American company, stands out as the food industry company with the highest number of granted patents, totaling 15. Based on this review, it is concluded that while a significant number of patents have been granted in recent years, there is still a lag in developing countries. Furthermore, more studies are needed to determine acrylamide in starchy food matrices subjected to immersion frying different from potatoes.
... Metode pengeringan ini banyak digunakan pada industri skala menengah dan besar. Kelebihan lain dari metode ini adalah produk yang dihasilkan memiliki kualitas yang lebih baik dari pengeringan dengan metode penjemuran (Pankaj & Keener, 2017). Berdasarkan penelitian yang telah dilakukan, produk tepung onggok dengan metode pengeringan oven memiliki warna, dan aroma yang lebih baik dibandingkan tepung onggok dengan metode penjemuran konvensional (Sari dkk, 2013). ...
Salah satu upaya untuk mengurangi biaya penyediaan energi panas adalah menggunakan energi matahari. Namun, energi matahari sangat bergantung pada cuaca yang sulit dikontrol oleh manusia. Oven menjadi solusi utama dalam industri yang beroperasi secara kontinu.Salah satu perkembangan teknologi oven adalah sistem rotary dryer yang memiliki pengeringan lebih merata. Namun, sistem tersebut masih mengkonsumsi energi panas yang besar. Konsumsi energi yang besar dapat direduksi dengan mengurangi tekanan ruang pengering hingga lebih kecil dari tekanan atmosfer (tekanan vakum) yang berakibat pada penurunan titik didih air. Dengan demikian, kandungan air dalam produk dapat menguap pada temperatur yang lebih rendah. Densitas udara pada kondisi vakum lebih kecil dibanding kondisi atmosfer. Menurunnya densitas udara menyebabkan jumlah energi panas yang dibutuhkan untuk menaikkan temperatur udara lebih sedikit. Investigasi awal karakteristik laju perpindahan panas transien pada rotary dryer bersirip dilakukan dengan studi numerik. Hasil yang diperoleh menunjukkan waktu yang dibutuhkan sebesar 30.33 detik untuk menaikkan temperatur produk dari temperatur lingkungan hingga mendekati temperatur dinding ruang pengering pada tekanan 10 KPa, dan 47,67 detik pada tekanan 50 KPa, selanjutnya 81 detik pada tekanan 1 atmosfer. Dengan demikian, ruang vakum berputar dapat mempercepat waktu pemanasan dan layak dilanjutkan dengan studi eksperimental. One of the efforts to reduce the cost of providing heat energy is to use solar energy. However, solar energy is highly dependent on the weather, which is difficult for humans to control. Ovens are the leading solution in industries that operate continuously. One of the developments in oven technology is the rotary dryer system which has more even drying. However, the system still consumes a large amount of heat energy. Large energy consumption can be reduced by reducing the drying chamber pressure to less than atmospheric pressure (vacuum pressure), resulting in a decrease in the boiling point of water. Thus, the water content in the product can evaporate at lower temperatures. The density of air under vacuum conditions is smaller than atmospheric conditions. The decrease in air density causes the amount of heat energy needed to raise the air temperature less. Numerical studies carried out initial investigations of the transient heat transfer rate characteristics in fin rotary dryers. The results obtained show that the time needed is 30.33 seconds to raise the product temperature from ambient temperature to close to the drying room wall temperature at a pressure of 10 KPa, 47.67 seconds at a pressure of 50 KPa, and 81 seconds at a pressure of 1 atmosphere. Thus, a rotating vacuum chamber can speed up drying time and is worth continuing with experimental studies.
... Были изучены многочисленные методы снижения содержания жира в жареных продуктах, в том числе: создание съедобного физического барьера (пленки) на продуктах, изменение поверхности продуктов, их предварительную обработку, новые методы жарки (жарка в вакууме, горячем воздухе и микроволновой печи или их комбинация), контроль полярности масла для жарки путем частой замены свежего масла и модификация жарочной среды путем корректировки температуры, времени или метода жарки [14,19,45]. Одним из простых приемов является промакивание поверхности продукта впитывающей бумагой, либо сдувание горячим воздухом или перегретым паром поверхностного масла с продукта, а также поддержание постоянной температуры, препятствующей охлаждению и образованию «вакуумного» эффекта [1]. ...
Fried foods are valued all over the world for their taste. Breading systems play a special role in the textural properties of such products. Changes in the dietary habits of the population contribute to an increase in the consumption of products in batter and breadcrumbs. The aim of the work was to summarize and analyze scientific publications on breading systems, their classification, composition, the role of individual components in the formation of quality, as well as the effect of deep frying on oil absorption and ways to reduce it. The object of the study was peer-reviewed foreign and domestic scientific literature, placed in the Scopus, Sciencedirect, RSCI databases. Methods of search, selection, systematization, generalization and analysis of scientific publications are used. It has been determined that the term breading systems can characterize any combination of components applied to the semi-finished product to create a crispy crust and the desired taste during further heat treatment. The main role as traditional breading systems is given to wheat gluten proteins, which, when kneaded, form a structural matrix with adhesive properties. An analysis of scientific literature has shown that one of the problems of breaded products is an increased calorie content due to the absorption of oil during cooking. Among several mechanisms of this process, the greatest role is given to the "vacuum" effect during cooling of the product. Fat absorption is affected by the properties of food and cooking oil. It has been established that one of the effective ways to reduce fat absorption is the formation of a barrier film with additional ingredients of the food matrix (proteins of animal and vegetable origin, cellulose derivatives and various gums), as well as the use of new frying techniques. It is shown that this direction is of interest for further research and opens up new opportunities for the industry to form products in demand.
... Meanwhile, good stability of frying oil and low oil consumption can be achieved in the MVF process (Albertos et al., 2016;Quan et al., 2014). However, uneven heating by localized microwave heating in the MVF process was reported, which caused oil quality deterioration (Pankaj & Keener, 2017). ...
Microwaves are electromagnetic waves of specific frequencies (300 MHz–3000 GHz), whereas ultrasonic is mechanical waves of specific frequencies. Microwave and ultrasonic technology as a new processing method has been widely used in food processing fields. Combined ultrasonic and microwave technology is exploited by researchers as an improvement technique and has been successfully applied in food processing such as thawing, drying, frying, extraction, and sterilization. This paper overviews the principle and characteristics of ultrasonic‐ and microwave‐assisted food processing techniques, particularly their combinations, design of equipment, and their applications in the processing of agricultural products such as thawing, drying, frying, extraction, and sterilization. The combination of ultrasonic and microwave is applied in food processing, where microwave enhances the heating rate, and ultrasonic improves the efficiency of heat and mass transfer. The synergy of the heating effect of microwave and the cavitation effect of ultrasonic improves processing efficiency and damages the cell structure of the material. The degradation of nutrient composition and energy consumption due to the short processing time of combined ultrasonic and microwave technology is decreased. Ultrasonic technology, as an auxiliary means of efficient microwave heating, is pollution‐free, highly efficient, and has a wide range of applications in food processing.
... According to some scientists, an increase in the moisture binding ability increases the adhesive qualities of minced fish, the elasticity of the resulting minced fish, the shear stress decreases, and the functional properties improve [31]. Introducing up to 3% salt into minced meat improves the rheological characteristics of minced meat, increasing the solubility of proteins [32]. Some scientists say adding less than 1% of table salt to minced meat is not recommended. ...
In the context of the problem of the organization of high-quality nutrition for consumers, the ways of its solution by expanding the range of products based on raw fish materials are considered. The necessity of creating combined semi-finished products with adequate substitution for plant components is justified, which allows increasing the amount of dietary fiber consumed and reducing the caloric content of the product, enriching minced fish with carbohydrates (polysaccharides and dietary fibers), amino acids, as well as macro- and microelements. Thus, a comparative analysis of the content of essential amino acids in the muscle tissue of fish in the inland waters of the Republic of Kazakhstan with some oceanic and marine fish showed that the content of amino acids such as leucine, lysine, threonine, phenylalanine is slightly higher. They are characterized by a high content of essential amino acids limiting the biological value, g/100 g of protein: lysine – 8.8-11.6; methionine – 2.1-3.1; tryptophan – 1.0-1.1. The data analysis shows that a higher pH value of fish meat corresponds to a higher elasticity value. The pH shift to the alkaline side of more than 7.5, although it promotes the release of myosin, reduces the elasticity of meat. In our study, we used minced fish from Carp, Pikeperch, Bream, and Pike. It was found that with the addition of 30% of the functional supplement of kelp, the moisture-retaining capacity of the fish semi-finished product was 48.6% and pH 6.67. With the addition of 30% of the functional pumpkin additive, the moisture-retaining capacity of the fish semi-finished product was 49.27% and pH 6.04. Developing semi-finished fish products with plant components makes it possible to obtain products of high biological value with a juicy consistency, which meets modern trends in healthy nutrition.
... The availability and consumption of foods that are heavily fried has shown that frying is one of the cooking methods (Pankaj and Keener, 2017). During the frying process, oil and food ingredients are exposed to moisture and oxygen at high temperatures, which causes important chemical reactions such oxidation, hydrolysis, and polymerization. ...
Acrylamide (AA) is an industrial chemical used in the production of polyacrylamides: It was discovered in food during the thermal processing (frying, baking, grilling, and roasting, among other things) of a wide range of foods (mostly starchy foods). Frying is one of the pathway for acrylamide formation, in which oil is heated to temperatures above the smoke point, which results in the production of acrolein known as the acrolein pathway. The formation of acrylamide during frying is influenced by a variety of factors. The article examines the factors contributing to the formation of acrylamide in various fried food products. These factors include processing time and temperature, type of oil, size of food, reused oil, food type and brand, storage conditions, presence of antioxidant in oil and so on.
... Some other factors such as preprocessing and salt of the food material before frying also need to be indicated. The pre-processing (pre-drying, blanching, modification) of raw materials (shape, thickness, porosity, density and moisture), and batter and coatings (lowmethoxyl pectin, hydroxypropyl methylcellulose, almond gum, basil seed gum and whey proteins) before frying are usually concerned [226][227][228][229]. A relationship between salt and TFAs contents was reported in frying food. ...
The trans fatty acids (TFAs) in food are mainly generated from the ruminant animals (meat and milk) and processed oil or oil products. Excessive intake of TFAs (>1% of total energy intake) caused more than 500,000 deaths from coronary heart disease and increased heart disease risk by 21% and mortality by 28% around the world annually, which will be eliminated in industrially-produced trans fat from the global food supply by 2023. Herein, we aim to provide a comprehensive overview of the biological effects, analytical methods, formation and mitigation measures of TFAs in food. Especially, the research progress on the rapid, easy-to-use, and newly validated analytical methods, new formation mechanism, kinetics, possible mitigation mechanism, and new or improved mitigation measures are highlighted. We also offer perspectives on the challenges, opportunities, and new directions for future development, which will contribute to the advances in TFAs research.
... During vacuum frying, low pressure is achieved using either liquid ring or oil sealed vacuum pumps. It is becoming more popular in current times as a result of new research discoveries proving a link between traditional fried food intake and human health risks (Pankaj and Keener 2017). A vacuum frying chamber, a cold condenser, and a vacuum pump make up a vacuum frying system (Diamante et al. 2015). ...
Fats are important for humans, animals, and plants because of their high energy content, which accounts for large amount of energy storage in the smallest amount of food material. Fats enable humans and animals to absorb fat-soluble vitamins as well as provide essential fatty acids, which their bodies seem unable to synthesize. Since, fat in food is almost entirely reabsorbed by the body, fat as a food has a very high efficiency. Many dishes benefit from fats because they give them a smooth, creamy consistency, which results in a pleasant mouthfeel. Fats and oils have numerous applications in food such as in snack foods, milk products, bakery and confectionary products owing to different physical and sensory characteristics of these products. During processing oils and fats undergo various physico-chemical modifications which define the characteristics of the product. This chapter deals with basic understanding of fats, utility of fats and oils in different food products and modification in fats during processing.
... Radiant frying is performed by utilizing high-temperature radiant emission to enhance the heat flux pattern caused by a food product during oil immersion frying. In this method, heat is transferred from the infrared source to the food materials at a frequency range from 0.78 to 1000 mm ( Pankaj & Keener, 2017 ). Electromagnetic waves are also employed in microwave heating, but the infrared heating system is more thermally efficient, and the heating capabilities are faster. ...
Background: Deep-fat fried foods are widely popular due to their distinct organoleptic and sensory characteristics. Deep-fat frying allows physical and chemical structural changes at the macro and micro levels. One of the greatest concerns regarding fried foods is their high oil content, and the excessive consumption of these foods has been linked to a range of metabolic diseases, including heart ailments, obesity, high cholesterol, and high blood pressure.
Scope and approach: This review paper presents a comprehensive and up-to-date review of various innovative frying processes, such as vacuum frying (VF), microwave frying, microwave-assisted vacuum frying (MVF), ultrasound combined microwave vacuum frying (UMVF), air frying, and radiant frying. Additionally, it explains the oil uptake mechanism, oil quality, and the effects of different pretreatments and post-frying treatments on the frying process.
Key findings and conclusions: Innovative frying processes are considered promising and capable of producing healthier fried foods compared to traditional frying; they reduce oil uptake without deteriorating organoleptic and sensory characteristics. Specifically, vacuum-assisted frying technologies, such as VF, MVF, and UMVF have significantly reduced oil uptake and acrylamide production while preserving oil quality. In addition, appropriate pretreatment and post-frying techniques play an essential role in reducing oil uptake and optimizing the frying process by saving energy.
... The unique sensory characteristics of fried foods are the main reason why they enjoy consumer preference, including fat content that improves texture and flavor [15]. The continuous increase in consumer awareness of healthy and safe fried products has led to research on these products [16,17]. Thermal processes are important stages that improve the sensory acceptance of various foods that are needed for human nutrition. ...
The quality of fried products affects consumer purchase decisions, and frying is an important stage in the production process. The objective of this research was to evaluate the thermophysical properties, the sensory quality, and microstructure of Colombian coastal Carimañola traditionally manufactured, in atmospheric frying and vacuum frying conditions. Lower moisture and fat content were reported in samples fried under vacuum compared to samples fried under atmospheric conditions, which is associated with the vacuum pressure during the process. Thermophysical properties, related to heat transfer in the samples, showed a correlation between thermal conductivity and moisture content. The micrographs visualized the changes in the porous structure of the coastal Carimañola. A greater effect was evidenced in the samples obtained by atmospheric frying because higher temperatures were used. The sensory evaluation reflected a preference for Carimañolas made with conventional frying. This research provides a basis for consumer purchases of traditionally fried products made with vacuum frying.
... Traditional deep-fried foods with high oil absorption often have potential negative effects on human health. In order to reduce the amount of oil absorbed by fried food, researchers have been conducting a series of experimental studies to improve the effectiveness of various deep-fried technologies (Pankaj & Keener, 2017). For example, the vacuum frying technique can be used to fry food in the absence of air (Fan, Zhang, & Mujumdar, 2005). ...
3D printing technology has a wide range of application in the food industry. Current research has focused on the improving printing accuracy and expanding the range of printing materials, while the feasibility of 3D printing technology in controlling processing characteristics and improving technological aspects have not yet been critically reviewed. This paper provides a concise critical evaluation of techniques to enhance the characteristics of 3D printed foods including their post-processing e.g. drying, frying, baking, cooling. sterilization etc. This paper provides guidance for future research and development in the field of post-treatment of 3D food printed products which is critically important for wider industrial application of this rapidly evolving technology.
... Frying is one of the established cooking methods evidenced by high fried food consumption [1]. During frying, oil and food substances are exposed to moisture and oxygen at high temperatures, resulting in significant chemical reactions, namely the oxidation, hydrolysis, and polymerization. ...
This study aims to investigate the effect of different vegetable oils and frying cycles on acrylamide formation during the intermittent frying of beef nuggets. Different vegetable oils, palm olein (PO), red palm olein (RPO), sunflower oil (SFO), and soybean oil (SBO), were used for a total of 80 frying cycles. Oil was collected at every 16th frying cycle and analyzed for peroxide value (PV), p-anisidine value (p-AV), free fatty acid (FFA), total polar compound (TPC), polar compound fractions, and fatty acid composition (FAC). Total oxidation (TOTOX) value was calculated, and acrylamide content was quantified in the nuggets. Regardless of the oil type, PV, p-AV, and TOTOX initially increased but gradually decreased. However, FFA and TPC continued to develop across the 80 frying cycles. The C18:2/C16:0 remained almost unchanged in PO and RPO but dropped progressively in SFO and SBO. The lowest acrylamide content in fried products was observed in the PO, while the highest content was observed in RPO. Bivariate correlation analysis showed no significant (p ≤ 0.05) correlation between oil quality attributes and acrylamide concentration. The oil type but not the frying cycle significantly affected the acrylamide concentration in beef nuggets.
Deep-fat frying is a popular cooking method known for its quickness, simplicity, and ability to impart desirable culinary characteristics to a variety of foods. The process involves complex heat and mass transfer mechanisms, which cause physical and chemical changes in both the food and the frying oil. Excessive consumption of fried foods, on the other hand, has negative health consequences due to increased oil absorption and the formation of harmful compounds.
Microwave frying combines microwave heating with conventional frying to increase heat and mass transfer efficiency. Shorter frying times, lower oil content, enhanced product texture and color, and lower acrylamide concentrations are all advantages of microwave frying. This chapter gives insight into microwave frying as an alternative cooking method.
Foods are fried by utilizing liquid oil as a heating medium and cooking them for brief periods of time at comparatively high temperatures. Because it is quick, tasty, crispy, and readily available, fried food is consumed all around the world. The type of batter used, the frying oil used, the moisture content, and the length of time the meal is fried all affect how much oil is absorbed by the food. The Indian market offers a wide selection of fried meals, both vegetarian and non-vegetarian. They come in both packed and unpackaged forms, including tikki, namkeens, samosas, kachori, vadas, and sev. But several studies revealed that eating fried food increases risk of developing several health issues, including cancer, fatty liver, obesity, and cardiovascular and type 2 diabetes (T2DM). To reduce the risk of these chronic health issues, it has been recommended that fried food be avoided. Instead, goods that have been air-fried, vacuum-fried, baked, roasted, etc., should be chosen, along with nutrition education. Keywords: fried foods, packed foods, deep fried foods, fried non-veg foods, fried veg foods.
Deep fat fried food products have been considered as a vital dietary contributor to certain chronic diseases, including the risk of atherosclerosis, cancer and hypertension. Hence, many food industries are focusing on low fat fried products to attract consumers. In general, oil is absorbed during deep fat frying, and this century old process is used for preparing various kinds of fried food products such as potato chips, banana chips, savory snacks, etc. Vacuum frying, electric field frying and two-stage frying technologies have been developed as an alternatives to traditional frying. These two technologies are suitable for most fried products; however, they may not be suitable for sugar based fruits as they can lead to the formation of browning reactions, which are generally considered unacceptable. This review aims to cover recent work done in the area of vacuum frying and two-stage frying, including the role of pre-treatment and post-treatment novel methods. Additionally, emphasis has been given on recent innovations to improve the quality of vacuum and two-stage frying, particularly concerning the reduction of oil uptake in fried food products.
The use of radiation in the microwave spectrum has been developed since the beginning of the 20th century with radars and communication systems. The expansion of this technology in other fields has allowed more and more possibilities for food industry applications. Applications of microwave technology to food processing include common unit operations such as drying, cooking, tempering, baking or frying; but it has also shown great potential for food process monitoring, food waste valorization processes through components extraction or biorefinery approaches, as well as for the development of functional foods and ingredients. Volumetric heating, faster reaction rates or MW promoted structural changes, are some of the characteristics of this technology which makes it interesting to be used in food and food waste processing. This chapter reviews the possibilities of the use of radiation in the microwave range in the food industry, considering present applications and prospects.
The impact of heat on food processing is important for improving the sensory and nutritional characteristics of foods while also increasing the shelf life by decreasing enzymatic and biochemical degradation reactions and removing water from the food structure. In addition to the positive features of heat application, it should also be considered that it requires high operating costs. The high-temperature food processing methods reviewed in this chapter include cooking, baking, roasting, frying, and thawing, which are unit operations in which heat is applied to foods to increase the shelf life or to improve the eating quality. In this chapter, first, the theoretical basis of the food processing operations is described. Then, processing parameters and the influence of the unit operations on the physicochemical and nutritional properties of foods are indicated. The methods and equipment used to apply these theoretical principles into practice are described in detail, and new technologies providing energy savings, lower labor costs, and improving product quality are discussed in the following sections.
Microwave (MW) is considered one of the most sustainable technologies in the food and agriculture sector with zero residual waste. Microwave radiation can heat food particles with dielectric properties. Food particles absorb that energy and convert it into heat energy, enabling its potential usage in food processing and preservation. The primary aim of this article is to provide an overview of current trends in the application of MW treatment to food products. Treatment includes sterilization, pasteurization, thawing, blanching, stunning, drying, and assisting with MW. Several advantages, including low processing time (50%), minimum production cost, and effect on food products, have also been described. Recent studies about the ability of MW to extract bioactive compounds from various biomass sources are also discussed, along with its advantages, drawbacks, and prospects.
Deep-fried meat products are widely popular. However, harmful compounds produced by various chemical reactions during frying have been shown to be detrimental to human health. It is of great necessity to raise practical suggestions for improving the oxidation problem of frying oils and frying conditions in some aspects. Vegetable oils are not as thermally stable as saturated fats, and blended oils have higher thermal stability than single oil. In this review, we discussed the oxidation problems frying oils and meats are subject to during frying, starting from the oil oxidation mechanism, the effects of different oils and fats on the quality of different fried meats under different conditions were concluded to alleviate the oxidation problem, to highlight the necessity of applying blended oils for frying, and effective antioxidants added to frying oils are also introduced, that would provide more convenient and practical options for obtaining higher quality of fried meat products and offer better understanding of the potential of blended frying oils for frying meat products.
Our previous study proposed preparation method of tocopherol (Toc) loaded ethyl cellulose (EC) particles as antioxidant due to instability of Toc under high temperature. The present study aimed to explore the antioxidant mechanism of loaded particles. Results showed that loaded particles prepared by EC of different viscosities (EC9, EC70, EC200) had antioxidative effect, and the antioxidant activity increased with EC viscosity. Fourier transform infrared analysis demonstrated that the interaction between EC and tocopherol was mainly hydrogen bond. Loaded particles retained effectively the thermal degradation of Toc and thus enhanced the antioxidant activity. Further investigation into thermal oxidation of EC inferred the possible antioxidative mechanism included two aspects. One was that Toc was fixed in the network structure of loaded particles formed by EC to provide a barrier for avoiding degradation. Another was that EC and Toc acted on different stages of lipid oxidation, playing the antioxidative effect together.
Frying is commonly used by consumers, restaurants, and industries around the globe to cook and process foods. Compared to other food processing methods, frying has several potential advantages, including reduced processing times and the creation of foods with desirable sensory attributes. Frying is often used to prepare starchy foods. After ingestion, the starch and fat in these foods are hydrolyzed by enzymes in the human digestive tract, thereby providing an important source of energy (glucose and fatty acids) for the human body. Conversely, overconsumption of fried starchy foods can promote overweight, obesity, and other chronic diseases. Moreover, frying can generate toxic reaction products that can damage people’s health. Consequently, there is interest in developing alternative frying technologies that reduce the levels of nutritionally undesirable components in fried foods, such as vacuum, microwave, air, and radiant frying methods. In this review, we focus on the principles and applications of these innovative frying technologies, and highlight their potential advantages and shortcomings. Further development of these technologies should lead to the creation of healthier fried foods that can help combat the rise in diet-related chronic diseases.
Ogel-Ogel which are Pemalang typical snacks so far have been less able to full fill the Indonesian National Standard on the quality of extruded snacks (SNI-01-2886-2015) due to their conventional frying techniques (manual deep frying). This study was aimed to evaluate the color appearance and chemical characteristics of Ogel-Ogel as a result of the application of the automatic frying system with a vacuum technique (vacuum frying) in the production process. The results show that Ogel-Ogel fried by the vacuum frying technique had a significantly brighter color display with lower in the fat content and TBA value, while protein content was higher compared to deep frying techniques. Meanwhile other chemical characteristics such as water content, carbohydrates, and ash did not show significant differences as a result of different frying techniques. Thus Ogel-Ogel as a Pemalang typical snack cooked with a vacuum fryer has a brighter color display with chemical characteristics that are more in line with SNI as an extruded snack. Thus, it has a potency to be the featured product from Pemalang area.
Background
Due to the increasing trend in consumer habits to use healthy food products with low fat content, reduction of oil uptake during different frying processes is necessary. Recent studies have clearly revealed that microstructural changes occurred during frying operations significantly impact oil uptake. These variations are assessed for better comprehension of the mechanisms involved in oil absorption of fried products to minimize oil uptake without sacrificing organoleptic and textural properties of the foods. Different strategies such as state-of-the-art computational simulations based on numerical analysis of simultaneous momentum, heat and mass transfer modeling during frying have been attempted by several researchers to better control the process.
Scope and approach
This review paper presents a comprehensive and up-to-date review of microstructure variations covering all existing methods of frying operations comprising deep-fat frying, vacuum frying, hot-air frying, non-fat frying and microwave frying together with post-frying treatments and process modeling of frying.
Key findings and conclusions: Oil uptake can be controlled during frying by proper process design regarding different products and frying operations. Textural and organoleptic characteristics of fried foods are affected by applying various frying processes. Microstructural changes and post-frying treatments influence oil uptake during frying. In addition, suitable design and optimization of frying using process modeling is important to produce fried food products with high quality.
Frying is one of the most common units in food processing and catering worldwide, which involves simultaneous physicochemical and structural changes. However, the problems of traditional frying technology, such as low thermal utilization and poor processing efficiency, have been gradually exposed to industrial production. In this paper, strategies of applying physical fields, such as pressure field, electromagnetic field, and acoustic field in frying technology separately or synergistically with improved efficiency and quality attributes are reviewed. The role of physical fields in the frying process was discussed with modifications in heat and mass transfer and porous structures. The effects of physical fields and their processing parameters on moisture loss kinetics, oil uptake, texture, color, and nutrients retention of fried food are introduced, respectively. Recent advances in multi-physical field-based frying techniques were recommended with synergistic benefits. Furthermore, the trends and challenges that could further develop the multi-physical field-based frying techniques are proposed, showing further commercial prospects for the purpose. The application of physical fields has brought new inspiration to the exploitation of efficient and high-qualified frying technologies, while higher technical levels and economic costs need to be taken into consideration.
• Highlights
• The role of physical fields in pretreatments and frying process were reviewed.
• The mechanism of physics fields on frying efficiency and quality was summarized.
• The physicochemical and microstructure changes by physics fields were discussed.
• The synergy of physical fields in frying technology were outlined.
• The trends for further multi-physical field-based frying techniques were proposed.
Vacuum and atmospheric deep-frying were employed to obtain blackberry-based snacks using unripe papaya as matrix. Papaya slices were osmotically impregnated with blackberry juice and fried between 126°C and 154°C at atmospheric pressure and between 110°C and 127°C under vacuum conditions. A response surface methodology (RSM) was used to define which responses (water activity, moisture and oil content, L*, C*, H*, hardness and degree of liking (DOL)) were significantly related to frying parameters (time and temperature). Then a principal component analysis (PCA) was applied to choose which ones related to DOL. PCA demonstrated that hardness and hue were the main drivers of liking for atmospheric frying, while for vacuum frying they were color and oil content. A second RSM was calculated to choose optimal processing conditions. Optimum conditions were 6 min at 117°C in vacuum frying and 6 min at 130°C and 3 min at 150°C in atmospheric pressure.
We investigate the efficiency of using a coating made from novel hydrocolloid basil seed gum (BSG), salep, and a mixed solution of BSG and salep as well as oil origin (canola or palm olein) to reduce oil absorption in deep-fried potato strips. We also evaluate the coating pick up, its effect on moisture content, frying yield value of fried potatoes and flow behavior of the coating suspensions. Flow curves show that all the studied suspensions are pseudoplastic and have shear thinning characteristics. The most effective coating formulations were 0.5 % BSG and 1.5 % salep. For these formulations, maximum oil uptake reduction was 28.8 and 28.7 % for potato strips compared to uncoated samples; the increase in moisture content was 29.1 and 17.5 %, respectively. Furthermore, the increase in moisture content resulted in an increase in frying yield up to 16.62 % for 0.5 % BSG. The oil type significantly (p < 0.05) influenced oil uptake.
Several active components naturally available in plants are strongly considered as good antioxidants to retard the lipid oxidation. Response surface methodology was used to investigate the effects of frying temperature (150-180 °C) and concentration of four plant-based active components (60-350 mg/kg oil); curcumin, cinnamaldehyde, thymol and carvacrol on oxidative stability of corn and palm oils. According to induction time values, the stability of oils drastically decreased with increasing temperature. Curcumin and cinnamaldehyde showed no significant effect (p > 0.05) on both oils. Carvacrol significantly increased induction times of corn and palm oils, but thymol was effective in palm oil only (p < 0.05). An actual frying experiment was carried out with only corn oil to confirm efficiency of carvacrol. The free fatty acid (%), peroxide value (meq/kg), para-anisidine, and total polar component values (%) of the fresh oil were 0.080, 2.55, 2.85, and 7.5, respectively. These values changed to 0.144, 1.47, 12.01, 10.0, respectively for the control oil; 0.138, 2.27, 11.49, 10.0 for BHT-added oil; 0.132, 1.42, 5.66, 9.5 for carvacrol-added oil after 30 frying cycles. Therefore, carvacrol could be considered as a good alternative to BHT for preservation of oils at frying temperatures.
Fried food consumption and its effects on cardiovascular disease are still subjects of debate. The objective of this review was to summarize current evidence on the association between fried food consumption and cardiovascular disease, diabetes, hypertension and obesity and to recommend directions for future research. We used PubMed, Google Scholar and Medline searches to retrieve pertinent publications. Most available data were based on questionnaires as a tool to capture fried food intakes, and study design was limited to case-control and cohort studies. While few studies have reported a positive association between frequencies of fried food intake and risk of coronary artery disease, heart failure, diabetes or hypertension, other investigators have failed to confirm such an association. There is strong evidence suggesting a higher risk of developing chronic disease when fried foods are consumed more frequently (i.e., four or more times per week). Major gaps in the current literature include a lack of detailed information on the type of oils used for frying foods, stratification of the different types of fried food, frying procedure (deep and pan frying), temperature and duration of frying, how often oils were reused and a lack of consideration of overall dietary patterns. Besides addressing these gaps, future research should also develop tools to better define fried food consumption at home versus away from home and to assess their effects on chronic diseases. In summary, the current review provides enough evidence to suggest adverse health effects with higher frequency of fried food consumption. While awaiting confirmation from future studies, it may be advisable to the public to consume fried foods in moderation while emphasizing an overall healthy diet.
The effects of ultrasound-assisted, supercritical CO2 and solvent extraction methods on antioxidant activity of Ziziphus mauritiana (Lam.) extracts investigated using DPPH and β-carotene assays. Ethanol-water extract of jujube obtained with ultrasound-assisted extraction (UJEW) had the highest antioxidant activity. Ultrasound-assisted extraction was the most effective method on extraction of phenolic compounds. Effect of UJEW in stability of soybean oil was compared to synthetic antioxidants by measuring total polar compounds, carbonyl value, peroxide value, free fatty acids, oxidative stability index, conjugated dienes and trienes values. Results showed UJEW at 600 ppm had higher stabilization efficiency than commercial antioxidants BHA, BHT and TBHQ.
In this study the effect of vacuum frying (VF) and traditional frying (TF) on oil degradation, fatty acid composition and alpha-tocopherol content was investigated. Two different refined sunflower oils were used: sunflower oil with high oleic acid content (HOSO) and sunflower oil with synthetic antioxidant (tertiary-butylhydroquinone) (TBHQ-SO). Oil degradation was monitored by measuring the free acidity (FFA), peroxide (PV), p-anisidine (p-AV),) total polar compounds (TPC) and oxidative stability (OE). Oils samples were taken every 4h of frying during 10 consecutive days. Values of FFA, p-AV, TPC using TBHQ-SO with traditional frying were (0.201, 207.0, 25.0) significantly higher than the obtained values with vacuum frying (0.073, 25.8, 11.2). The same parameters by using HOSO were (0.327, 82.0, 21.9) with traditional frying and (0.099, 33.3, 6.4) with vacuum frying. The EO was 2.44 and 7.95 with TBHQ-SO traditional and vacuum frying respectively, and with for HOSO 0.65 and 2.67, respectively. The polyunsaturated fatty acids percentage decreased in all treatments except in TBHQ-SOv. The alpha-tocopherol content decreased in all treatments at different rates. At the end of the frying processes the percentages of alpha-tocopherol reduction were TBHQ-SOv (4.90%), TBHQ-SOt (53.62%), HOSOv (96.87%), HOSOt (99.76%).
The effect of finish heating method (oven heating, immersion frying and controlled dynamic radiant (CDR) heating) on mechanical properties, color and sensory properties of par-fried French fries was evaluated. Peak breaking force was highest for CDR-heated French fries. An equivalent b value (yellowness) for the crust of immersion-fried and CDR-heated French fries was found by using color analysis. Sensory evaluation indicated overall acceptability of CDR-heated French fries equivalent to immersion fried-French fried potatoes. Finish heating of par-fried French fries using CDR heating showed promise to produce a reduced-fat fried product, as well as an alternative process to traditional immersion finish frying.
The marinated and battered chicken leg meat and breast meat were pressure fried and their physico-chemical qualities were
compared to the conventional fried product (open pan deep fat frying). Shrinkage due to frying process was significantly lesser
in case of pressure fried leg meat (PLM) and breast meat (PBM) as compared to products prepared by conventional frying leg
meat (CLM) and breast meat (CBM). Also, juiciness of pressure fried chicken products was superior (p ≤ 0.05) than fried products obtained by the conventional method. PLM and PBM had lower fat content (p ≤ 0.05) compared to conventionally fried CLM and CBM. Lipid oxidation was higher (p ≤ 0.05) in conventional frying as compared to pressure frying. Irrespective of the type of chicken meat, conventionally fried
meat required higher shear force as compared to pressure fried products. Salmonella, Staphylococcus aureus, Shigella and E. coli were not detected. The study indicates the usefulness and superiority of pressure frying in comparison to conventional deep
fat frying.
KeywordsBattered fried chicken–Pressure frying–Conventional frying–Juiciness–Hunter colour–Texture
Lipid class and fatty acid profile of pressure fried (PF) and conventionally fried (CF) chicken and medium of frying were
evaluated. Depending on the frying cycle, neutral lipid (NL) content of PF chicken varied from 75–86% as compared to that
of CF (84–90%). Similarly, glycolipid (GL) content varied from 11–21% in PF and from 9–12% in case of CF. Phospholipid (PL)
was the least among lipid classes in both the products. The fresh frying medium (oil before frying cycle started), NL, GL
and PL were 89, 10 and 0.33%, respectively. After the frying cycles were over, NL content of oil used for CF decreased to
82% and GL content increased from 10 to 17%. There was no significant difference (p ≥ 0.05) between the contents of lipid classes of oil used for PF or CF. Fried chicken and frying medium had higher concentration
of linoleic acid and oleic acid irrespective of the frying cycle or frying method. PF chicken had moisture content in the
range of 56–58% and total fat was 14% whereas in case of CF chicken it ranged from 49–52% and 18% respectively. TBA and FFA
values of CF chicken and oil on repeated frying were higher (p ≤ 0.05) than PF. In comparison to conventional frying, pressure frying resulted in relatively tender and juicier product
presumably due to better retention of moisture (p ≤ 0.05) and low oil uptake.
KeywordsFried chicken–Pressure frying–Conventional frying–Fatty acid composition–Thio barbituric acid–Lipid class
For decades, frying has been a popular technique for the preparation of foods, both on domestic and industrial scales. The effects of edible oil type and frying operation conditions on the shelf-life of fried products, the deterioration progress and the health hazards of fried foods have been studied by various researchers. To achieve a clear conception of the present situation, a collection of the results obtained from previous studies about product deterioration and safety issues due to the frying process, along with related tables, are of prime importance. According to the studies, it can be concluded that a vacuum, oil replenishment, frying temperature, and time of process are the most important parameters affecting the quality of oils and fried products; hence, by controlling them, it is possible to prevent the formation of toxic compounds and loss of nutritional components to a considerable extent during frying operation. Furthermore, according to recent studies indicating significant formation of toxic compounds before the chemical indices of the oil reach the disposal point, more studies are needed to determine whether they are formed at levels that compromise safety and affect consumers’ sensory perception before the established discard points.
en A comparative analysis of quality attributes (moisture, fat, color, and relaxation modulus) of French fries was performed between conventional and microwave frying. Experiments were performed in triplicate for both frying operations at temperatures of 177, 185, and 193 °C for frying times of 60, 90, and 120 s. The real‐time pressure and temperature profiles at above conditions indicated that during microwave frying, gage pressure had greater magnitudes that lasted longer, and the temperature increased to boiling point of water faster in comparison to conventional frying. Lower magnitude of negative pressure during microwave frying is expected to have caused lower fat content in fries obtained using this method (0.08 g/g solids less at 185 °C and 0.07 g/g solids less at 193 °C) than conventional frying. The lightness parameter (L*) decreased to a lesser extent in microwave frying than in conventional frying. The stress relaxation function of the French fries were significantly different between the 2 frying operations. Consumer test confirmed that reduced fat uptake during microwave frying did not compromise with desirable quality attributes of French fries. X‐ray micro‐computed tomography scanning provided complementary understanding about differences in microstructural properties of fries made using microwave and conventional frying.
Practical Application
pt The mechanisms and quality attributed discussed in this study compare conventional and microwave frying, which will be useful for the food industry to evaluate potential advantages and limitations of the 2 frying methods.
The objective of this study was to evaluate the ability of microwave-assisted frying (MVF) technology to reduce the oil uptake and improve quality attributes of fried potato chips. Potato chips were produced using MVF and vacuum frying (VF) technologies and the oil uptake, residual moisture content, microstructure, texture (crispness) and color attributes of chips were compared. The effects of microwave power density (12, 16 and 20 W/g), frying temperature (100, 110 and 120 °C) and vacuum degree (0.065, 0.075 and 0.085 MPa) in MVF were evaluated. Results showed that the oil uptake in MVF samples was significantly lower than VF samples, decreased from 39.14 to 29.35 g oil/100 g dry solid. The moisture evaporation rates were accelerated and the MVF produced crispier chips with better natural color. Higher microwave power densities resulted in faster water evaporation rates and lower breaking force. Higher frying temperature led to faster water evaporation, lower oil content and faster color change. Higher vacuum degree bring about faster water evaporation, lower oil content and less color change. Observation of microstructure showed that the cellular structure and integrity of cell wall in chips was better preserved by MVF.
Concern for the nutritional quality of chips is growing due to rising consumption, motivating research and development of new snack products that contribute to a lower calorie and fat intake in the diet while retaining their good flavor and facility of consumption. The objective of this study was to investigate the behavior of cassava chips, blanched or unblanched and processed under either atmospheric or vacuum frying conditions, in order to determine the influence of these treatments on mechanical and acoustic parameters, optical properties and oil absorption. Vacuum frying trials (17 kPa) were conducted at 120, 130 and 140 °C and compared with frying at atmospheric pressure (101.3 kPa) at 165 °C. Pre-blanching brings a considerable improvement in the color of the vacuum-treated samples and less oil absorption. Vacuum frying pre-blanched cassava chips may be an alternative to atmospheric frying since it improves the color of the samples, reduces the oil gain and maintains crispness. The treatment at 130 °C under vacuum conditions after pre-blanching achieved the best results.
The aim of this work was to investigate the impact of almond gum as coating agent to decrease the oil absorption and to increase the moisture content of fried potato chips meaning a Box-Behnken design. The studied parameters were: almond gum concentration (0-20 g/L), frying time (30-120 s) and frying temperature (160-190 °C). Results showed that the increase of almond gum concentration up to 20 g/L decreased the oil uptake of potato chips by 34% and increased the moisture by 29.5%. Optimal coating and frying conditions found with RSM were thus achieved with 20 g/L aqueous almond gum, 75 s frying time at 160 °C frying temperature. Additionally, the study of sensorial analysis (color, appearance, crispiness, taste, odor, appetence) showed that the chips coated with almond gum have an overall acceptability better than the uncoated potato chips, and the ones coated with arabic gum. The textural analysis of potato chips showed that the hardness (rigidity) decreased significantly by coating either with almond gum or arabic gum. The results obtained through this work showed that coating with almond gum improves the sensorial and nutritional qualities of potato chips.
Whey protein has been investigated for its oil barrier properties in fried foods. Whey protein has been implemented successfully non-film forming applications to reduce the fat content of deep-fried chicken. As a 10% postbreading dip, whey protein solutions significantly lowered oil absorption of boneless patties by 37% compared to undipped controls. In bone-in chicken thighs, 10% whey protein postbreading dip caused a 15% reduction in oil absorption during frying which was doubled by 10% β-lactoglobulin postbreading dip at pH 2. A 30% lipid reduction was observed in deep-fried battered and floured chicken strips when the strips were dipped in a 10% solution of denatured whey protein prior to frying compared to control chicken strips. When added to the batter of deep-fried chicken nuggets, a significant fat reduction was observed for nuggets to which 3% whey protein was added to the batter compared to the control. In chicken strips that were marinated in a 15% solution of whey protein, a 35% fat reduction was observed. In spite of these results, questions that still remain. These studies have been undertaken in fully cooked products, not in raw coated or par-fried products. The impact of rethermalization method is not known. Only preliminary research on the impact of WPI on the frying oil with respect to the formation of polar materials has been undertaken. On the positive side, the processes for introducing whey protein as an oil inhibition agent utilize processing steps that are already very common, e.g. incorporation into the batter or a marinade. Whey protein has the potential to be employed as an oil inhibiting agent in fried foods especially as it is relatively inexpensive and easy to come by.
Abstract
Optimization of processing conditions (temperature 122 to 136°C, vacuum pressure 9.91 to 19.91 cmHg, and frying time 3 to 9 min) during vacuum frying of plantain chips was investigated using a Box-Behnken experimental design with response surface methodology (RSM). Models for various responses were developed and optimized frying conditions using numerical solutions were established. Optimized vacuum fried samples were compared with atmospheric fried samples based on the concept of equivalent thermal driving force (ETDF). Frying parameters had significant (p<0.05) effects on the moisture content, texture, and color with a coefficient of determination (R 2) for quadratic model responses varying between 0.53 and 0.99. Optimum vacuum frying conditions for plantain chips were a frying temperature of 133°C, vacuum pressure of 9.91 cmHg, and frying time of 6 min based on desirability concepts. Vacuum fried plantain chips had more acceptable sensory properties, based on ETDF values, than atmospheric fried samples.
We investigated the applicability of microwave-assisted vacuum frying in producing potato chips. Three microwave power levels (600, 800, 1000 W) were used for frying times of up to 360 s. The moisture loss and oil uptake histories were measured as a function of the microwave power levels. The textural crispness (breaking force) and color parameters (lightness, redness, and yellowness) were also measured as a function of microwave power levels and frying time. The application of microwave-assisted vacuum frying significantly increased the moisture evaporation and oil uptake rates in potato chips. At the same time, the amount of oil uptake was similar to that in vacuum-fried chips not assisted by microwave. The chips produced using microwave-assisted vacuum frying were crispier (lower breaking force), visually appealing, and could be produced in a shorter time.
Deep-fat frying is a complex, thermal chemical process that produces fried foods with desirable colour, appearance, flavour, and texture. Normally, less stable liquid oils are hydrogenated to enhance their oxidative stability for deep-fat frying purposes. However, considerable amounts of trans and positional isomer fatty acids are formed during hydrogenation, which are nutritionally undesirable. The stability of frying oils is sometimes increased by careful blending of polyunsaturated oils with more saturated oils. The natural way of improving oxidative and flavour stability of frying oils and fats is by adding natural antioxidative components and precursors present in the plant kingdom, such as 'virgin' olive oil, sesame seed oil (SSO) and rice bran oil (RBO). A variety of natural antioxidative components, present in these oils, comprise tocopherols and tocotrienols, special sterols e.g. Δ5-avenasterol and sterol esters, squalene, sesamolin, sesamol, sesaminol and related compounds, polyphenols, etc. Various antioxidative components present in SSO and RBO are largely retained in Good-Fry® Constituents (GFC), manufactured according to European patent as well as USA and worldwide patent applications pending (Silkeberg and Kochhar, 2000)
Low-fat and high dietary-fiber diets are important elements in the prevention of chronic diseases. The objective of this work was to understand the effect of wheat bran inclusion in large amounts to a gluten–starch matrix, in structure formation and associated quality attributes, during deep-fat frying. Matrices were prepared mixing 12 g of gluten and 88 g of wheat starch per 100 g of dry solids, ensuring a moisture content of 40 g water/100 g dough. Starch was gradually replaced by wheat bran (up to 40 g/100 g dry solids), and lack of structure formation was overcome by partially replacing starch with pregelatinized corn starch. Samples were fried at 170 °C and oil absorption in high fiber products was reduced through post-frying centrifugation. Pregelatinized corn starch addition allowed obtaining an adequate structure in formulations with high wheat bran content, reducing oil absorption by 35% in formulations with up to 20 g wheat bran/100 g dry solids. It was possible to obtain a low-fat product (70% reduction) with high fiber content (40 g/100 g dry solids) after centrifugation, confirming the importance of oil absorption during post-frying cooling.
The goal of this research was to test vacuum-frying as an alternative process in order to make fried chicken nuggets healthier. The compositional, textural and sensory properties of vacuum-fried chicken nuggets were evaluated and compared with the properties of deep-fat-fried nuggets. A sensory analysis of the fried products was conducted to assess consumer preferences. The higher rate of moisture loss observed during the first two min of frying in vacuum conditions. The decrease (p < 0.05) in the L* coordinate with frying time was more pronounced in vacuum conditions. a* and b* coordinates, both increased significantly (p < 0.05) with frying time and temperature, indicating that the temperature was the principal factor affecting the Maillard reaction for both treatments. Sensory analyses showed that vacuum-frying produced chicken nuggets with normal organoleptic characteristics but oil uptake was not significantly reduced.
Industrial relevance
Despite many studies have evaluated the effect of vacuum frying on fruit and vegetables, the researches on protein-based food vacuum frying are really scarce. Vacuum frying allows the use of low temperature and short oxygen rate during cooking process which it would be an interesting alternative in the output features in the frying industry. This study realized that chicken nuggets fried under frying vacuum conditions could provide products with compositional characteristics and sensory attributes similar to those from chicken nuggets fried by conventional deep fat frying, in addition to be crunchier.
The objective of this study was to investigate the effects of vacuum frying on the product quality of desalted grass carp fillets. Parameters of included moisture content, oil content, color values, and textures (hardness, chewiness, and springiness) were used to evaluate the product quality. Results showed that with increasing vacuum frying temperature and time, the moisture content of fillets decreased while the oil content increased, and hardness increased quickly. The hardness and chewiness values of vacuum-fried samples were both higher than those of atmospheric fried samples. However, there was no significant change in L* among four different temperature/vacuum-frying combinations. The results also indicated that vacuum frying at 0.08 MPa and 100°C–110°C for 15 min can produce crisp grass carp fillets with lower moisture and oil contents as well as good color and texture quality.
Deep-fat frying of foods usually is carried out under atmospheric conditions at temperatures near 190 °C. The problem that arises most often is excessive darkening or scorching of the product, even before the product is completely cooked. In addition, some of the oil decomposition products have been implicated in producing adverse health effects when fried oils degraded with continued use.Vacuum frying is a process that is carried out under pressures well below atmospheric levels (below 6.65 kPa). Vacuum-fried products have higher retention of nutritional quality (phytochemicals), color is enhanced (less oxidation), and oil degradation is reduced compared to atmospheric frying. However, a de-oiling mechanism is necessary to remove the excessive oil absorption at the surface of the product. The main objectives of this paper are to review the literature on vacuum frying specifically on the effect of vacuum frying operating conditions such as pressurization and de-oiling mechanisms on the final product oil content. Product quality attributes as affected by atmospheric and vacuum pressures and fundamental modeling of the process are also discussed in this article.
With limited success, numerous attempts have been made to reduce the fat content of oil immersion fried foods, while maintaining their unique characteristics. A recent advancement in frying is dynamic radiant frying. Radiant frying utilizes infrared energy to reproduce the heating profile generated during oil immersion frying without oil immersion. The result being a fried food with a crispy surface and similar temperature profile to immersion fried with significantly less oil. The goal of this study was to compare frozen, consumer-ready chicken patties, fried using the FryLess 100 K Radiant Fryer, and oil immersion frying, respectively. Properties compared included core and surface temperatures, oil content, moisture content, color, and peak shear force. Significant differences (P < 0.01) were observed in color, oil content, and moisture content. Radiant fried patties were slightly lighter in color and had an average of 16% less oil and 19% more moisture than the immersion fried. Sensory evaluation revealed that panelists preferred the flavor and less oily mouthfeel of the radiant fried patties, but preferred the crispness and appearance of the immersion fried patties. Panelists indicated no difference in overall preference signifying that radiant frying may serve as a viable alternative to oil immersion frying of some chicken products.
Use of microwave frying for food products may be considered as a new way of improving the quality of the fried foods. In this study, the effects of microwaves on quality of fried potatoes (moisture content, oil absorption, color and hardness) were studied and the process was optimized by using Taguchi Technique. Microwave power level (400W, 550W and 700W), frying time (2.0, 2.5, 3.0min) and oil type (sunflower, corn and hazelnut oil) were the parameters used in the study. Moisture content decreased whereas oil content, hardness and color of potatoes increased with increasing frying time and microwave power level. The potatoes with the highest oil content were found to be the ones that were fried in the hazelnut oil. The optimum condition was found as frying at 550W microwave power level, for 2.5min in sunflower oil. At this condition, the oil content of fried potatoes was lower than that of conventionally fried ones.
Fried foods have been enjoyed by man for thousands of years. The main reason is that these foods have unique and delicious sensory characteristics. This is one of the reasons that fried foods and frying is so popular, the other being that hot oil is an excellent heat transfer medium, so food cooks quickly. Fried food quality and, hence, its sensory properties, are affected by a number of parameters including the type of oil and its chemistry or quality. Once operators begin frying, the quality of that oil begins to change, but the bottom line is that the sensory properties of the food are directly affected by the changes in oil quality. These changes and part of the focus of this presentation will be the Surfactant Theory of Frying, which helps to explain why food fries.
Deep-fat frying is a rapid and low cost process widely used to prepare tasty food. During this cooking process, oil is used both as the heating medium and as an ingredient producing calorific products. Nutrition has become a major health issue, especially in developed countries where increasing obesity is a problem, particularly among children. Many food research projects involving snack food industries therefore attempt to understand oil uptake during the frying process in order to control and reduce the fat content of fried products without deteriorating their desirable organoleptic characteristics. The main objectives of this paper are to review the literature on the frying process and more precisely the mechanisms and parameters involved in the oil uptake phenomenon. Both products and processes will be considered and their influence via experimental results will be discussed.
The potential for using nitrogen gas as a pressurizing medium in a deep-fat fryer was investigated. Effects of different frying temperatures (150, 175 and 190C) and pressures (101, 163 and 184 kPa) on the fried food quality were studied. Chicken nuggets were either fried for a constant frying time of 240 s or at a constant core temperature of 70C in a modified restaurant-type pressure fryer. Modifications were made to include external gases to pressurize the frying chamber. The quality characteristics of the fried products were determined. An increase in pressure applied during frying resulted in tender and juicier fried products because of the reduction in moisture loss. The increase in pressure reduced oil uptake by the fried products. Compared with the use of steam released from the food, frying under nitrogen gas provided similar or better quality of fried products in terms of moisture retention, juiciness and texture.
This paper presents the development of the mathematical equations used for modeling immersion frying of an infinite slab. Immersion frying was viewed as a moving boundary problem similar to that found in freezing and freeze-drying. The infinite slab was divided into two regions, the crust and core, and macroscopic balances were used to develop the governing partial differential equations for heat and mass transfer in each region. Flux relations were proposed for the heat and mass transfer and incorporated into the partial differential equations. The final set of equations consisted of four non-linear partial differential equations and appropriate boundary conditions and initial conditions.
Over the past 5 years growing demands for reducing fat content of fried foods have greatly stimulated the amount of research spent on the issue of fat uptake during deep-fat frying. The results of these efforts are summarized in this review. Most of the increased understanding of the mechanism of fat uptake has been brought about by improved imaging techniques. It turns out that fat uptake is basically determined by two mechanisms: the condensation effect and the capillary effect. Major reductions claimed in literature and patents are found for coating and batter formulations using various types of biopolymers.
Consumption of hot chips is a convenience food in most countries. Unfortunately, these are high in fat and contribute to fat-related diseases in societies with a high fat consumption. There is substantial scope through best-practice deep-frying techniques for producing lower fat, high-quality chips. From a review of the literature, the main factors associated with a lower-fat content of chips are thick (>12 mm), straight cut chips; cryogenic freezing methods; low moisture content of potatoes (specific gravity >1.1); frying fat: chip volume ratio of 6:1; frying at optimal temperature (180 to 185 degrees C) during cooking and turning the temperature down (approximately 140 degrees C) and covering the vats during slack periods; vigorously shaking the basket and hanging it over the deep fryer to drain after frying; maintaining the quality of the frying fat by regularly skimming the cracklings, filtering the fat, and topping up the fryer with fresh fat; keeping the fat turnover <5 days; regular cleaning of frying equipment. It is important that all deep frying operators are adequately trained in these techniques. It is also important that the frying medium is low in saturated and trans fatty acids (<20%) because of their effects on blood lipids and low in linolenic acid (<3%) because it is readily degraded. The widespread implementation of best-practice deep-frying would reduce fat content of hot chips and thus lower overall fat consumption.
Three mechanisms have been previously proposed to explain the complex process of oil uptake during deep-fat frying. The mechanisms reviewed are water replacement, cooling-phase effect and surface-active agents. The former mechanism describes mainly oil uptake of relatively large voids in the fried food created due to water evaporation. The second mechanism furnishes an explanation for the significant amount of oil absorbed when the food is removed from the fryer. At this point, product surface characteristics and oil viscosity play paramount roles. Surface-active agents' formation provides only a limited explanation for the increased oil uptake during prolonged frying. Reviewed literature, theory and new data show contradicting values and do not support the myth that during extended frying time the surfactants generated reduce the contact angle and/or the interfacial tension, and consequently, influence oil uptake significantly. Higher oil uptake after extended frying time is probably related to higher oil viscosity caused by polymerization reactions and oil adherence to the product surface. Further research is needed for establishing the interrelationships between surface-active agents' formation and their effect on fried product oil uptake and quality to resolve this myth.