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Packaging Methods for Minimally Processed Foods
Abstract
Consumers demand for minimally processed foods have significantly increased, primarily due to their interest in fresh and convenience foods, modern social trends, single person households, and willingness to spend money for quality products (Yang et al. 1994; Singh et al. 2010). They constitute a full meal or a significant portion of it (fresh cut fruits, salads etc.), receive minimal processing treatments, often followed by refrigeration and freezing. A number of processing treatments applied to minimally processed foods do not ensure the ‘sterility’. The operations of washing, sorting, peeling and cutting necessary to produce ready-to-eat products result in the reduction of the shelf life of the fresh-cut produce, with respect to the intact product, due to the accelerated enzymatic activity, moisture loss and microbial proliferation (Lucera et al. 2010). A large number studies have been conducted to prevent the detrimental phenomena occurring after cutting; most of them are based on treatments with reducing agents, acidifying agents, chelating substances and antimicrobial compounds (Lanciotti et al. 2004; Tripathi and Dubey 2004; Rico et al. 2007). In particular control of the enzymatic browning in fresh-cut commodities, ascorbic acid and citric acid are widely used alone or in combination as substitutes for sulphite (Gimenez et al. 2003; Lee et al. 2003; Rocculi et al. 2004; Cocci et al. 2006; Albanese et al. 2007). Different calcium salts have also been studied for decay prevention, sanitation and nutritional enrichment of fresh fruits and vegetables (Martin-Diana et al. 2007). Fresh cut fruits and vegetables have a limited shelf life, due to mechanical stress, cell and membrane damage, water loss, enzyme activity, and microbial proliferation (Conte et al. 2009). The use of innovative non-thermal processing methods such as ultra-high pressure processing, pulsed electric fields, microwave sterilisation, ionizing radiations and active packaging have extended the shelf life and increased the safety of minimally processed foods. Many factors influence the shelf life of fresh and convenience foods, and packaging is one of the key factors to keep the product fresh.
... M9, a high-barrier nanocomposite, has been introduced by Mitsubishi Gas Chemical Company for juice or beer bottles, multi-layer films, containers, etc. [74]. Absorbent pads and liners, Dri-Loc® manufactured by Cryovac ® are suitable for meat, fish, and poultry, while Cryovac ® OS films are useful for smoked and processed meats, cheeses, baked goods, fresh pasta, and dry food products such as coffee, nuts, drink, and baking mixes as well as other snack food items [259,260]. ...
The demand for innovative solutions has arisen from the inevitability of improved packaging systems to protect processed food from various factors that cause spoilage. Traditional food packaging materials have limitations in fulfilling all the requirements of consumers, such as being inert, cheap, lightweight, easily degradable, reusable, and resistant to physical abuse. Nanofillers incorporated in the polymer matrix can provide potential solutions to these challenges. This review paper deliberates the use of nanofillers in a polymer matrix to develop an active and intelligent polymer nanocomposites-based processed food packaging system. The present review article focuses on the properties of nanofillers and their potential benefits when incorporated into the polymer matrix. It also examines the challenges associated with developing such packaging systems and explores the ways to address them. It highlights the potential of nanofiller-based polymer nanocomposites in developing a novel food packaging system that can improve the shelf-life and quality of processed food. Such systems can protect food from dirt or dust, oxygen, light, moisture, and food-spoiling microorganisms. Incorporating nanofillers can provide a viable solution to these problems. Most importantly, this paper provides research insights into the potential benefits of nanofillers-based polymer nanocomposites and their applications in the food packaging industry. The verdicts of this review will be of interest to the food packaging industry, entrepreneurs and researchers interested in developing sustainable and innovative packaging systems.
... 23986/afsci.130323 products are stored in packages containing 70% N 2 and 30% CO 2 (Wani et al. 2015). In these packages, CO 2 gas (≥ 20%) is used to prolong the lag phase of aerobic bacterial growth and reduce the growth rate in the logarithmic phase. ...
In this study, dried chicken slices were packaged in MAP (modified atmosphere packaging) and AP (atmospheric packaging), and stored at 4 °C and 25 °C. The CO2 content of MAP packaged samples decreased as the storage temperature and time increased. The slices exhibited lower aw values when they were packaged in AP at 25 °C. The pH increased from 6.1 to 6.2, 2-thiobarbituric acid reactive substances (TBARS) increased from 10.6 to 37.3 µmol MDA kg-1, and non-protein nitrogen (NPN) increased from 4.9 to 5.3 g 100 g-1 in MAP for 90 days of storage. The microbiological quality of the samples was assessed by enumerating total aerobic mesophilic bacteria (TAMB), total psychrophilic bacteria (TPB), Micrococcus/ Staphylococcus, lactic acid bacteria (LAB), Enterobacteriaceae and yeast-mold, and was higher in the sample stored in MAP at 4 °C. Moreover, the sensory quality was determined by sensory evaluation with a 9-point hedonic scale. When the sensory and microbiological qualities were evaluated together, the shelf lives of the samples were determined to be 90 days at 4 °C and 75 days at 25 °C for MAP and 45 days at 4 °C and 30 days at 25 °C for AP. It could be concluded that the cold dried chicken slices can be stored in MAP for 90 days without much change in physicochemical, microbiological, and sensory quality.
... Packaging generally keeps FCFVs under different conditions compared to the normal air composition, thus they are classified as under controlled atmosphere (Wani, Singh, Pant, & Langowski, 2015). In the case of FCFVs, this modification usually results on an environment low in oxygen and/or high in carbon dioxide, this influencing greatly in the metabolism on the food product extending its shelf-life (Siddiqui, Chakraborty, Ayala-Zavala, & Dhua, 2011). ...
The awareness in modern society about the importance of healthy eating habits contributing to overall health and well-being has contributed to major changes in eating patterns. Nowadays, consumers demand products ready to be utilized, maintaining their fresh attributes and high nutritional value. Aligned with this trend, probiotic microorganisms in products such as fresh-cut fruits and vegetables (FCFVs) have the potential to be a good alternative for consumers looking for produce low in cholesterol, or with allergies to milk proteins (such as lactose intolerant), or just with vegetarian habits. The incorporation of probiotic microorganisms adds a safety net by antagonism or production of antimicrobial peptides such as bacteriocins. This chapter centers on presenting the feasibility of the incorporation of probiotic organisms in minimally processed products as FCFVs, this based on their viability, stability, adherence, antagonist response, and potential control against pathogen organisms.
... Comprehending the technique of adding pouches or pads first, they are present at the bottom, either tightly attached or loosely bound at any interior of the package ( Wani et al., 2015). They have addition of volatile antimicrobial chemicals into packages; or the addition of non-volatile antimicrobial chemicals directly into the polymers. ...
A successful packaging technique demands certain barriers for microbes, achieved through controlled conditions to indicate microbial growth, levels of oxygen, harmful bacterial and fungal toxins, moisture levels, and the indicators for temperature and time. Active food packaging is greatly being applied these days for food safety against harmful microbes. Food is protected from biological, physical, and chemical damages caused by pathogenic microbes through different technologies of packaging including modified atmosphere packaging and controlled atmospheric packaging through antimicrobial films. Moreover, it is essential to use selective materials suitable for different food stuffs for the maintenance of nutritional value of foods. Use of various gas scavengers and bio-based package designing are also greatly helpful towards enhanced shelf life of food products.
... Other inorganic OS have also been explored, including hydrogen, hydrazine, carbohydrazine, and sulfites. Cerium oxide-based OS have been developed with unique advantages including being readily active without an activator, i.e., moisture, dual abilities to scavenge both O 2 and moisture at relatively competitive capacities and rates for dry and intermediate moisture foods and pharmaceuticals; metal detector-and microwave oven-friendly, physically and visibly unchanged after performing the scavenging function, and available in both sachet and embedded active olefin polymer (OxyCatch TM , Kyodo Printing Company; OmniBatch Ò and OmniKeep Ò , PowderTech International) (Wani et al., 2015). ...
The food industry has been under growing pressure to feed an exponentially increasing world population and challenged to meet rigorous food safety law and regulation. The plethora of media consumption has provoked consumer demand for safe, sustainable, organic, and wholesome products with "clean" labels. The application of active and intelligent packaging has been commercially adopted by food and pharmaceutical industries as a solution for the future for extending shelf life and simplifying production processes; facilitating complex distribution logistics; reducing, if not eliminating the need for preservatives in food formulations; enabling restricted food packaging applications; providing convenience, improving quality, variety and marketing features; as well as providing essential information to ensure consumer safety. This chapter reviews innovations of active and intelligent packaging which advance packaging technology through both scavenging and releasing systems for shelf life extension, and through diagnostic and identification systems for communicating quality, tracking and brand protection.
Packaging is intended to conveniently contain foods and to protect them against a range of hazards during storage and distribution. This chapter describes the barrier properties of different packaging materials and their relationship to the shelf life of foods. It summarises interactions between packaging materials and foods and describes in detail the different types of metal, glass, paper and plastic food-packaging materials. It then reviews modified atmosphere packaging and developments in edible and biodegradable packaging, active and intelligent packaging, and printing techniques. The chapter concludes with a discussion of aspects of the environmental issues surrounding food packaging, including plastics pollution, reductions in materials and energy use, and recycling.
Kurutma, eş zamanlı olarak ısı ve kütle transferi ile gıdadan suyun uzaklaştırılmasına dayanan kompleks bir işlemdir. Kurutulmuş et ürünleri; sığır, domuz, kümes hayvanları ve balık gibi farklı et kaynağı, baharat, antioksidan ve stabilizatörler gibi fonksiyonel katkı maddeleri ve kürleme, tütsüleme ve kurutma gibi üretim yöntemlerinin kullanılmasıyla çeşitli şekillerde üretilir. Bu yöntemlerle elde edilen kurutulmuş et ürünlerine pastırma, ham, jerky, pemmican, biltong, kaddid ve cecina örnek verilebilir. Ancak, kurutma işlemi sıcaklık ve süre gibi çeşitli faktörler yönünden optimum koşullarda yapılmadığında, et ürünlerinde esmerleşme reaksiyonları, renk kaybı, lipit oksidasyonu, yoğun ve sert bir yapı, boyut küçülmesi, rehidrasyon yeteneğinin azalması gibi birtakım olumsuz değişiklikler meydana gelebilir. Ayrıca, depolama koşulları da kurutulmuş et ürünlerinin kalitesi üzerinde önemli bir etkiye sahiptir. Bu makalede kurutulmuş et ürünlerinin kalite özellikleri ve depolama işleminin ürün kalitesi üzerine etkileri derlenmiştir.
The key elements responsible for the quality of food are the technologies used to process raw materials and preserve obtained products. The aim of this paper was to investigate the effect of package type (bags made from low density polyethylene [PE‐LD] and the metallized polyethylene terephthalate [PET met/PE foil]) on selected quality parameters of the chilled stored red sauerkraut. Vegetables were analyzed before packaging and after 1, 2, 3 and 4 months of chilled storage in two types of a package. It has been found that the package type used had no statistically significant (P > 0.05) effect on vitamin C, total polyphenols, thiocyanates contents and antioxidant activity of the chilled stored red sauerkraut.
Practical Applications
Red cabbage is commonly occurring in a diet as an additive to meat dishes and other rich‐in‐fat products, which favor tumor transformation. Due to high consumption and availability throughout the year cabbage, both fresh and sour could potentially be a significant element in chemoprevention of cancer. Sauerkraut, despite the losses in some components, retains a high nutritional value and is additionally enriched with precious constituents positively affecting the consumers' health. Furthermore, its flavor raises significantly that, in turn, contributes to increasing consumption compared to the raw cabbage. Vegetables are a delicate raw material for storage. Selections of suitable packaging materials guarantee high quality of products with regard to their sensory and nutritional characteristics.
RESUMEN La carne es una matriz rica en nutrientes que proporciona un entorno adecuado para la proliferación de diversos microorganismos, deteriorantes y patógenos. Dentro de estos últimos se encuentra E. coli O157 y no‐O157, Salmonella spp. y Listeria monocytogenes. Por otro lado, la creciente demanda de productos " similares a los frescos " con calidad sanitaria, organoléptica y nutrimental ha impulsado el desarrollo de tecnologías alternativas con el objetivo de suplir a las tradicionales o térmicas y garantizar de esta forma lo que el consumidor solicita. Es por tal razón que en las últimas décadas se ha trabajado intensamente para desarrollar nuevas técnicas de preservación alimentaria que no modifiquen las características sensoriales y nutricionales, además, que mantengan o mejoren la estabilidad y calidad microbiológica. En el presente escrito se revisan los microorganismos patógenos más comunes presentes en carnes y sus productos, así como tecnologías emergentes tales como altas presiones hidrostáticas, radiación, empaques activos e inteligentes y uso de compuestos naturales para su control. Palabras Clave: carne, productos cárnicos, microorganismos patógenos, control no térmico.
RESUMEN La carne es una matriz rica en nutrientes que proporciona un entorno adecuado para la proliferación de diversos microorganismos, deteriorantes y patógenos. Dentro de estos últimos se encuentra E. coli O157 y no‐O157, Salmonella spp. y Listeria monocytogenes. Por otro lado, la creciente demanda de productos " similares a los frescos " con calidad sanitaria, organoléptica y nutrimental ha impulsado el desarrollo de tecnologías alternativas con el objetivo de suplir a las tradicionales o térmicas y garantizar de esta forma lo que el consumidor solicita. Es por tal razón que en las últimas décadas se ha trabajado intensamente para desarrollar nuevas técnicas de preservación alimentaria que no modifiquen las características sensoriales y nutricionales, además, que mantengan o mejoren la estabilidad y calidad microbiológica. En el presente escrito se revisan los microorganismos patógenos más comunes presentes en carnes y sus productos, así como tecnologías emergentes tales como altas presiones hidrostáticas, radiación, empaques activos e inteligentes y uso de compuestos naturales para su control. Palabras Clave: carne, productos cárnicos, microorganismos patógenos, control no térmico.
Minimally processed fruits are an important area of potential growth in rapidly expanding fresh cut produce. However, the degree of safety obtained with the currently applied preservation methods seems to be not sufficient. The interest in the possible use of natural compounds to prevent microbial growth has notably increased in response to the consumer pressure to reduce or eliminate chemically synthesized additives in foods. The aim of this work is to give an overview on the application of natural compounds, such as hexanal, 2-(E)-hexenal, hexyl acetate and citrus essential oils, to improve the shelf-life and the safety of minimally processed fruits as well as their mechanisms of action.
The concept of antimicrobial packaging has received great attention because of its potential to enhance food safety. Several
studies have explored its applications and effectiveness to suppress pathogenic microorganisms. However, few studies have
analyzed the alterations caused in the engineering properties of food-packaging polymers after the incorporation of antimicrobials.
Such information is very important to understand the feasibility of producing antimicrobial packaging films on the industrial
scale. This review explores the work done so far to evaluate how the incorporation of antimicrobial substances affects the
properties of food-packaging systems. This article also emphasizes diffusion studies on antimicrobial substances through packaging
films and the analytical solutions used to characterize this diffusion mechanism. Our review found that although the properties
of packaging materials are altered by the addition of antimicrobials such as organic acids, enzymes, and bacteriocins, every
packaging material is unique, and these effects cannot be generalized.
KeywordsActive packaging–Antimicrobial packaging–Gas barrier properties–Tensile strength–Thermal properties–Diffusion
The use of calcium lactate solutions has been shown to be a healthy alternative to chlorine washing in order to maintain the shelf-life of fresh-cut products. The aim of this research was to analyse the effects of calcium lactate (15 g L-1) treatment at 25 degrees C and 50 degrees C (heatshock) on the textural properties of sliced carrots and to compare those with the chlorine treatment (120 mg L-1) widely used in industry. Several direct and indirect markers of textural changes in carrots during storage were used: Instron textural analysis, Cryo-SEM and optical microscopic, sensory analysis, pectin methylesterase (PME) activity, calcium content and water activity. Samples treated with calcium lactate maintained texture significantly (p < 0.05) better than samples treated with chlorine throughout storage. Calcium lactate treatment produced a reduction in the water activity in sliced carrots and a higher firmness (Instron analysis) than chlorine treatment. In addition, combined use of heat-shock and calcium lactate treatment increased PME activity significantly when compared to the other treatments, results that were confirmed by sensory analysis. Cryo-SEM analyses showed that combined heat-shock and calcium lactate treatment was more effective in maintaining the turgor of cortex tissue cells and reduced the extent of lignification at cutting-edge areas. The use of calcium lactate combined with heat-shock is a promising washing method for fresh-cut carrots in order to preserve their texture and improve their nutritional value, avoiding the use of chlorine washing. (c) 2006 Elsevier Ltd. All rights reserved.
The preservation of quality of fresh products is relevant for the industry due to its economic impact. This paper presents a comprehensive review of the use of different sources of calcium to preserve fresh fruits and vegetables in order to extend the shelf life and enhance the nutritional value. Emphasis is on discussing about the best sources of calcium, concentration, temperature and method of application, suitability of the commodities; and some hints for the cost/benefit analysis are presented.
Fresh lamb steaks were treated with three different preparations of natural antioxidants: one group was packaged with a rosemary active film, the second group was packaged with an oregano active film, and the third group was sprayed on the meat surface with a rosemary extract before packaging in a high-oxygen atmosphere. Samples were stored under illumination at 1±1°C for 13days. Metmyoglobin formation, lipid oxidation (TBARS), instrumental colour (CIE a(∗)), psychrotrophic bacterial counts (PCA), sensory discolouration and off-odour were determined. The use of a rosemary extract, a rosemary active film or an oregano active film resulted in enhanced oxidative stability of lamb steaks. Active films with oregano were significantly more efficient than those with rosemary, exerting an effect similar to that of direct addition of the rosemary extract; in fact, they extended fresh odour and colour from 8 to 13days compared to the control.
Food packaging is vital to provide physical protection, information, prevent contamination, and to extend the shelf life. Several food packaging materials and technologies are used to protect and extend the shelf life of fresh and processed food products. Plastic packaging materials are used more than other packaging materials but are facing lot of criticism due to migration of packaging constituents into the food as well as flavor scalping issues. Innovation in traditional packaging technologies has increased the shelf life, freshness and food safety. Food packaging method differs according to the physiological, chemical, and structural properties of food materials. The safety concerns on migration of packaging materials are regulated by several regulatory authorities. Migration compounds not only affect the flavor profile but also affect the human health. The factors influencing migration are temperature abuse to packaging materials, hot filling of food, microwave heating, use of recycled plastics, etc. Chromatographic methods are commonly used to evaluate the overall migration and migration-specific compounds.
The growth of packaging technologies for use with nonthermally and minimally processed foods is discussed. The presentations at the 2005 IFT Annual Meeting + Food Expo® provided pragmatic insights into the individual technologies and the present and potential connections among them. Differen packaging technologies addressed include ionizing radiation, microwave sterilization, pulsed electric fields, ultra-high-pressure processing, active packaging, antimicrobial effects, surface activation, and aseptic packaging. Connecterra, a Cambridge, Mass.-based high-tech company specializing in infrastructure software for RFID, uses RFID to read the electronic product code (EPC), the unique identity for each package.
This chapter introduces the electromagnetics of microwaves, presents the general needs of the packaging intended to be used in microwaves, as well as the several different kinds of microwavable packagings. Furthermore the most important regulations are shown, before some commercial examples are given. The chapter concludes by referring to continuative literature and commercial addresses.
A great technological development for food packaging has been developed over the past few decades to satisfy consumer demands relating to more natural forms of preservation, and methods to control packaging and storage for assurance and food safety. Active packaging is, certainly, one of the most important innovations in this field. Active packages are designed to perform a role other than to provide an inert barrier between the product and the outside environment, using the possible interactions between food and package in a positive way to improve product quality and acceptability. Active food packaging is a heterogeneous concept involving a wide range of possibilities which globally can be grouped in two main goals: (i) to extend shelf life, and (ii) to facilitate processing and consumption of foods. In the first case, active packaging solutions include the systems studied to control the mechanisms of deterioration inside the package (i.e. oxygen scavengers, moisture absorbers or antimicrobial agents). In relation to the second goal, active packaging allows us to match the package to the properties of the food, to reduce costs of processing, or even to perform some processing operations in-package or to control the product history and quality. This paper reviews the different applications of active packaging and their commercial use, together with some legal aspects and future trends.
This chapter reviews active food packaging, an innovative concept developed to improve the safety and retain the quality of stored food as well as to extend its shelf life. In active packaging, subsidiary constituents deliberately have been included either in the packaging material or in the package headspace to enhance the performance of the system. There are three main categories of active packaging techniques, including those encompassing absorbers, releasing systems, and other systems. Examples include oxygen, moisture, CO2, ethylene and flavor scavengers, ethanol, CO2 antimicrobial and substance emitters. Antimicrobial food-packaging materials, for instance, extend the lag phase and reduce the growth rate of microorganisms, resulting in shelf-life extension while maintaining product quality and safety. Despite intensive research and development work, additional research is required to promote the usability of active food packaging as an effective tool to ensure the quality and safety of foods.
A solution for increasing the shelf-life of fresh and minimally processed fruits and vegetables is coating with edible films. A presentation of the materials that can be used as edible coatings and their properties is related to the fruits and vegetables on which they were tested. The combination of coating materials with antimicrobials is shown as a possibility to enhance the safety of ready-to-eat fresh produce. Technological, regulatory and economical aspects regarding usage of edible coatings are reviewed along with consumer perception, challenges for ecology and new research needs.
This paper summarises the test results on photo degradation of milk and dairy products, particularly yoghurt and butter, obtained by the authors and their colleagues over the past ten years. A large amount of data from relevant literature is also considered in this review. Two major aspects are treated: the extrinsic and intrinsic factors that influence photooxidation and the effects of light on chemical components and physico-chemical parameters of milk and dairy products. The principal extrinsic factors that influence photooxidation are: the spectrum and intensity of the light source, the conditions of light exposure (geometry, duration etc.), the degree of light transmittance and the oxygen permeability of the packaging material as well as the storage temperature of the product. These factors must be selected after careful consideration of the intrinsic factors responsible for the photosensitivity of the product. The latter include the composition (particularly oxidant and antioxidant contents), pH, redox potential and processing of the product.
Light induces loss of vitamins, especially riboflavin (which also acts as a photosensitiser),β-carotene and vitamin C, production or degradation of free amino acids, increase of the peroxide value, formation of sensorially unpleasant volatile compounds (methional, aldehydes and methyl ketones) as well as colour changes. The kinetics of these alterations and the limits of detection of the compounds involved are compared. Some practical recommendations complete this study.
Edible films and coatings have received considerable attention in recent years because of their advantages including use as edible packaging materials over synthetic films. This could contribute to the reduction of environmental pollution. By functioning as barriers, such edible films and coatings can feasibly reduce the complexity and thus improve the recyclability of packaging materials, compared to the more traditional non-environmental friendly packaging materials, and may be able to substitute such synthetic polymer films. New materials have been developed and characterized by scientists, many from abundant natural sources that have traditionally been regarded as waste materials. The objective of this review is to provide a comprehensive introduction to edible coatings and films by providing descriptions of suitable materials, reviewing their properties and describing methods of their applications and potential uses.
Active and intelligent packaging systems are continuously evolving in response to growing challenges from a modern society. This article reviews: (1) the different categories of active and intelligent packaging concepts and currently available commercial applications, (2) latest packaging research trends and innovations, and (3) the growth perspectives of the active and intelligent packaging market. Active packaging aiming at extending shelf life or improving safety while maintaining quality is progressing towards the incorporation of natural active agents into more sustainable packaging materials. Intelligent packaging systems which monitor the condition of the packed food or its environment are progressing towards more cost-effective, convenient and integrated systems to provide innovative packaging solutions. Market growth is expected for active packaging with leading shares for moisture absorbers, oxygen scavengers, microwave susceptors and antimicrobial packaging. The market for intelligent packaging is also promising with strong gains for time-temperature indicator labels and advancements in the integration of intelligent concepts into packaging materials.
The development of packaging systems able to maintain the food quality and safety of a food has benefited consumers and food manufacturers. Among others, antimicrobial packaging presents an excellent potential to be implemented as an innovative solution in food technology to reduce the microbial growth in food systems and extend food shelf life. Biobased and synthetic polymers are being functionalized with well-known antimicrobials such as enzymes, bacteriocins, natural extracts, organic acids, chelators and metal ions, showing excellent controlled release opportunities when used directly in contact with the food matrix or as part of combined strategies. However, the evaluation of the efficiency consists of a multidisciplinary approach and its effect in a food has to be studied case by case. This chapter provides an overview on the most recent scientific advances, state-of-the-art legislative requirements and a critical view of the benefits and limitations of the different antimicrobial packaging strategies. © 2014 Elsevier Ltd All rights reserved.
Purpose
– The purpose of this paper is to review the recent trends in the development of active packaging (AP) for foods.
Design/methodology/approach
– The most up‐to‐date and pertinent studies within the literature have been included and summated in this paper.
Findings
– Fresh foods are widely consumed and are becoming a major component of the international food market. During the last decades, the social and scientific modernization, the boom in customer's needs and demands, along with the major changes in the way food products are manufactured, distributed and retailed, led to the development of alternative or novel methods for the production and preservation of food products. This review will present the most comprehensive and current overview of the widely available, scattered information about the different AP technologies for the control of various critical parameters responsible for the quality and shelf life of fresh foods with an interest to stimulate further research to optimize different quality parameters.
Originality/value
– This paper offers a holistic view that would guide a reader to identify the recent developments in the field of AP.
Osmotic dehydration is gaining considerable attention as a minimal processing method because of its advantages such as saving energy to compliment drying process, better control of flavor loss and tissue damage problems and improved retention of color and nutritional constituents. The problems of flavor loss, tissue damage, color degradation and nutritional loss are present in traditional hot air drying due to the high temperature involved. However, except for candied food, large penetration of solute into the food becomes a major problem in osmotic dehydration. The application of a coating on food prior to osmotic dehydration is a promising solution to alleviate the large solute intake problem. Edible coatings serve as a barrier to limit the penetration of solute without having an adverse effect on water removal. This paper focuses on this combined technology and its potentials. The effects of edible coatings on both water and solute mass transfer in osmotic dehydration are reviewed. Suitable coating materials and their applicable concentration range for osmotic dehydration of food are evaluated. Mathematical models describing the mass transfer in osmotically dehydrated food with coatings are also reviewed.
The effects of an antioxidant dipping treatment (in an aqueous solution of 1% ascorbic acid (AA) and 1% citric acid for 3min) and of modified atmosphere (90% N2O, 5% O2 and 5% CO2) packaging (MAP) on some functional properties of minimally processed apples have been investigated. In particular, AA and total polyphenol (TP) contents and the overall antioxidant power of the product were monitored during 8 days of low temperature storage. Colour, texture and some chemical indices associated with the ripening stage of the product (titrable acidity and soluble solids content) were also evaluated. As a consequence of the anti-browning treatment, the AA content of dipped samples was about 20-fold higher than not treated samples at the beginning of storage and remained higher until the sixth day of refrigeration. Moreover, the dipping treatment resulted in an increase in the apple slice antioxidant activity, while MA had a negative effect on AA levels. As shown by the positive correlation between the AA and TP results, TP levels were higher for treated samples compared to those not treated over the whole storage period, because of the reducing action of AA that prevented a high level of TP degradation. Results of the other physico-chemical parameters investigated confirmed the synergistic preservative effect on the colour of MA, together with the dipping treatment, while structural decay of fruit tissue was evident due to the anti-browning chemical agents used.
In this work different packaging strategies aimed to prolong the shelf life of minimally processed zucchini are presented. In particular, two different cultivars (Sofia and Diamante) were tested. The sliced zucchini were packaged in oriented polypropylene-based (OPP) bag and into a bio-polymeric film (COEX) under passive and active MAP. The investigated produce was stored at 5°C for approximately 9days. Headspace gas concentrations, pH, mass loss, sensory quality and viable cell load of main spoilage microorganisms were monitored for the entire observation period. In order to determine the respiration activity, O2 and CO2 concentrations were monitored not only in OPP and COEX packages but also in the headspace of an aluminum-based package. Results suggested that for Diamante cultivar OPP film under active and passive MAP showed slightly better performances in prolonging the shelf life, compared to COEX film; instead, for Sofia cultivar better results were obtained with OPP film only under active MAP conditions.
For the design of modified atmosphere packaging with microperforated films it is necessary to know the respiratory kinetics of the product and the gas interchange through the packaging. The aim of this work was to describe an empirical equation that relates the microperforation area with the transmission rate in order to present a mathematical model, valid for packages of constant volume. The model should take into account the dependency of the respiration rate with the gas composition and the existence of a hydrodynamic flow through the microperforations. The evolution of the gas composition inside the package predicted by the model has been compared with the results of experiments conducted at 4°C with minimally processed peach (‘Andross’ and ‘Calante’ cultivars), fresh-cut cauliflower and whole black truffle, by using seven packages of different number (0–14) and size (from 90×50μm to 300×100μm) of microperforations. The respiratory kinetics of these products was previously determined in a closed system. It has been established that the rate of O2 consumption is a potential function of the O2 concentration, while the production of CO2 is linear, except in the case of the truffle which showed a linear dependency for O2 and CO2. The experimental data and those predicted by the model showed a satisfactory agreement for the O2, while the CO2 is underestimated for products with RQ1. The reason for this behaviour could be the CO2 concentration gradient within the package owing to the air flow that moves to compensate pressure differences.
Incorporation of free acids or salts of antimycotic food additives, including propionic acid, benzoic acid or sorbic acid, into low-density polyethylene (LDPE) films failed to inhibit mould growth when the films contacted inoculated media. However, LDPE films into which benzoic anhydride was incorporated exhibited antimycotic activity when in contact with media and cheese. Benzoic anhydride, which had been added to LDPE film, was hydrolysed within 5h and detected as benzoic acid in potato dextrose agar (PDA) and cheese after contact with the film. LDPE films, into which 1% benzoic anhydride was incorporated, completely inhibited Rhizopus stolonifer. Penicillium spp., and Aspergillus toxicarius growth on PDA. Lower amounts of anhydride partially inhibited growth by increasing the lag phase and reducing the rate of growth in most cases. LDPE films incorporated with 0.5–2% benzoic anhydride delayed mould growth on cheese. These data suggest that addition of antimycotic agents to LDPE during film manufacture may be a feasible way of controlling surface mould growth in foods such as cheese.
The atmospheres prevalent in borage packaged in 5 different films, together with different water-vapor permeabilities of the films, determined the evolution of the visual and microbiological quality of borage. PVC films proved inadequate to extend the sensory quality since the samples packaged with the films were spoiled on day 9, whereas among the P-Plus films, the least permeable film was the most adequate to extend the sensory quality of borage until day 15. For most of the treatments, no correlation between the microbial growth and changes in appearance was found. Thus, some treatments with a fair sensory evaluation had microbial counts higher than those allowed by the European legislation.
Low-density polyethylene film was coated with a solution containing a high-molecular-weight or low-molecular-weight methylcellulose and hydroxypropyl methylcellulose. Films contained 10000, 7500, 5000, 2500, or 0 IU/cm2 nisin. Film samples were placed into peptone water, and 10-μL samples were removed and placed onto spiral plated lawns of Listeria monocytogenes. Zones of inhibition were measured using a caliper. Films containing 5000, 7500, and 10000 IU/cm2 nisin inhibited L. monocytogenes after 30 min; films with 7500 and 10000 IU/cm2 nisin inhibited L. monocytogenes after 60 min and 8 h, respectively. No zones of inhibition were observed after 24 h and 4 d for all films. After 8 d, zones of inhibition were observed for films with all levels of nisin except 2500 IU/cm2. Films with 0 and 2500 IU/ cm2 nisin did not produce zones of inhibition throughout the study. Molecular weight of the cellulose-based carrier had no effect on inhibition of L. monocytogenes. A standard curve of inhibition was developed using solutions of 10000, 7500, 5000, 2500, or 0 IU/cm2 nisin applied directly to lawns of L. monocytogenes. The amount of inhibition using a direct application of a solution was 25% to 50% more effective for inhibition of L. monocytogenes compared with the coated film samples. Overall, the coated film samples were effective for inhibition of L. monocytogenes, particularly when 7500 and 10000 IU/cm2 nisin were used, but the release of nisin was not controlled and did not provide consistent inhibition throughout the 8-d study.
Surface microbial stability is a major determinant of the shelf life of refrigerated meat products. Surface microbial growth has also been noticed in intermediate moisture foods exposed to temperature fluctuations. One solution to this problem is to apply edible coatings to the food surface which control diffusion of antimicrobial agents into the food. Films with such properties were identified using a permeability cell. Methyl- and hydroxypropyl methylcellulose mixed with lauric, palmitic, stearic and arachidic acid significantly lowered the potassium sorbate permeation rate relative to cellulose ether films containing no fatty acids. Permeability determinations at 5, 24, 32 and 40°C showed excellent agreement with the Arrhenius activation energy model for the permeation process.
Calcium alginate films were prepared by the pH-controlled release of calcium ions into alginate solution or by the cooling of hot calcium alginate gels. Thermogravimetry and calorimetry showed that the controlled Ca release films contained a greater amount of high-temperature component, and required extra energy to dissociate the tightly crosslinked calcium alginate. Structural differences were reflected by the permeability of the two films to potassium sorbate: 1.06 × 10–7 (controlled Ca release) and 1.58 × 10–7 cm2sec–1 (cooled). Apparent activation energy was estimated to be for the diffusion of potassium sorbate 24.1 KJ·mol–1, sodium ascorbate 23.7, and ascorbic acid 36.2. Results suggested that the pH of the diffusant solution had an interactive effect on the alginate film.
Edible coatings controlling preservative migration from surface to food bulk could control surface microbial growth which is often the main cause of spoilage for many food products. In this paper we examine the potassium sorbate permeability behavior of chitosan, methyl cellulose and hydroxypropyl methyl cellulose based films. to gain an understanding of the permeation process, permeability determinations were done at 5, 24, 32 and 40°C. Permeability rates followed the Arrhenius activation energy model. A lack of breaking points in Arrhenius plots indicated that no morphological changes occur within these films in the 5 to 40°C temperature range. Activation energy values were found to be independent of film composition and were affected only by the solvent embedded in the film. This behavior was confirmed by analysis of the same permeability data using a modified Stokes-Einstein equation.
Methyl cellulose was the most promising diffusion barrier with a permeability constant of 3.4 and 1.4×10−8 (mg/s cm2) (cm)/(mg/cm3) at 24 and 5°C, respectively. Electron microscopy was used to examine the morphological characteristics of these films and showed they have no visible pores or channels at magnifications up to 10,000.
The apparent permeability constants for potassium sorbate and sorbic acid through an edible film composed of methylcellulose and palmitic acid (weight ratio 3:1) were evaluated as a function of water activity (aw) and pH. For films with thickness 55–66 μm, potassium sorbate permeability increased from 2.3 × 10−10 to 2.0 × 10−8 (mg/sec cm2)(cm)/(mg/mL) as aw increased from 0.65 to 0.80. Films were not stable at aw levels above 0.80. Permeability of the film to sorbic acid at aw 0.8 decreased from 3.3 × 10−8 to 9.1 × 10−10 (mg/sec cm2)(cm)/ (mg/mL) as pH increased from 3 to 7. At pH 3 the undissociated acid was 97.5% and at pH 7 it was 0.4%.
In response to the dynamic changes in current consumer demand and market trends, the area of Active Packaging (AP) is becoming increasingly significant. Principal AP systems include those that involve oxygen scavenging, moisture absorption and control, carbon dioxide and ethanol generation, and antimicrobial (AM) migrating and nonmigrating systems. Of these active packaging systems, the AM version is of great importance. This article reviews: (1) the different categories of AP concepts with particular regard to the activity of AM packaging and its effects on food products, (2) the development of AM and AP materials, and (3) the current and future applications of AM packaging.
Effect of edible coatings in combination with antibrowning agents on minimally processed apple slices was studied during storage at 3°C for 2 week. To control initial respiration rate of apple slices, edible coatings were applied to cut apples as semipermeable barriers against air. Initial respiration rate showed a decrease by 5% and 20% in carrageenan (0.5 g/100 mL)-coated and whey protein concentrate (5 g/100 mL)-coated apples, respectively, at 25°C. Edible coatings in combination with antibrowning agents effectively prolonged the shelf-life of minimally processed apple slices by 2 week when stored in packed trays at 3°C. Addition of various antibrowning agents to these coating solutions was advantageous in maintaining color during storage. Addition of CaCl2 (1 g/100 mL) significantly inhibited the loss of firmness. These edible coatings in combination with antibrowning agents also showed positive sensory analysis results and beneficial reduction of microbial levels. WPC (5 g/100 mL) containing ascorbic acid (1 g/100 mL) plus CaCl2 (1 g/100 mL) was the most effective preservation treatment in terms of sensory quality after 2 week.
Edible coatings made from alginate were investigated for their capacity to preserve the quality of minimally processed ‘Gala’ apples. Apple wedges were immersed in a calcium chloride solution and subsequently coated with one of three different coating formulations: alginate, alginate-acetylated monoglyceride-linoleic acid, and alginate-butter-linoleic acid. Apple wedges were stored at 5 °C in 85% RH. Weight loss, color, texture, volatiles profile, microbial load, titratable acidity, and soluble solids were assessed over storage. Overall, it was found that alginate coatings prolonged the shelf-life of cut ‘Gala’ apples without causing anaerobic respiration. All coatings used minimized the weight loss during storage, and apples with coatings containing acetylated monoglyceride in particular remained the closest to original weight. Firmness of coated apples remained practically constant regardless of the type of coating, while control apples had a large decrease in firmness during storage. Browning of ‘Gala’ apple slices was retarded in all coated apples. A higher production of hexanol and trans-2-hexenal was observed in coated apples containing butter and acetylated monoglyceride.
Antimicrobial effect of chitosan edible film incorporating garlic oil (GO) was compared with conventional food preservative potassium sorbate (PS) and bacteriocin nisin (N) at various concentrations. This activity was tested against food pathogenic bacteria namely Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, Listeria monocytogenes and Bacillus cereus. Mechanical and physical properties were characterized and Fourier Transform Infrared (FTIR) was also performed to determine functional groups interactions between the matrix and added agent. Incorporation of GO up to levels at least 100 μl/g, PS at 100 mg/g or N at 51,000 IU/g of chitosan were found to have antimicrobial activity against S. aureus, L. monocytogenes, and B. cereus. At these levels, the films were physically acceptable in term of appearance, mechanical and physical properties. GO components did not affect the physical and mechanical properties of chitosan films as it did not have any interaction with the functional groups of chitosan as measured by FTIR.
Blown PA6-based nanocomposite films were prepared and studied for a wide range of montmorillonite content (from 0 to 13 wt% of inorganic layers). The crystalline morphology of the polyamide matrix was shown to be only slightly dependent on the filler loading, allowing to discuss the nanocomposites water transport properties as a function of the filler content and dispersion state. The water vapour sorption mechanism of the polymer phase was found to be independent on the filler amount. In the range of activity between 0 and 0.9, the nanoclays behaved as impermeable fillers and the water barrier properties of the nanocomposite films were improved in comparison with the neat PA6 film thanks to a tortuosity effect. At higher activity, e.g. in liquid water, the clay aggregates were able to swell within the matrix, as this one was itself highly swollen. Hence, the equilibrium water uptake and the water permeability of the nanocomposite films highly depended at this water activity, on the clay dispersion state.
The effect of trehalose as an edible coating on minimally processed Annurca apple slices was studied during cold storage. The edible coating was prepared by dipping the fruit in a solution containing trehalose at 0.8%, sucrose at 1.0% and sodium chloride at 0.1%. During storage at 6 °C the following parameters were monitored: weight loss, colour (hue angle (h°) and whitening index (WI)), firmness, malic and ascorbic acids, polyphenol content, microstructure by scanning electron microscopy (SEM) and microbial count. The results showed that such a coating reduced the browning phenomena; in fact the WI and h° values were significantly lower in coated samples than untreated ones. Moreover, decreases in weight loss and in the reduction of organic acids were observed in coated samples. Electron microscopy slides of the cut tissue showed how the coating worked.
Modified atmosphere packaging (MAP) with non-conventional gas mixtures in combination with non-sulphite dipping was tested during refrigerated storage on minimally processed (MP) apple slices for the physico-chemical characteristics. `Golden Delicious' apple slices were dipped in an aqueous solution of 0.5% of ascorbic acid (AA), 0.5% of citric acid (CA), and 0.5% of calcium chloride (CC) to slow down the enzymatic browning. Apple slices were sealed in polypropylene boxes and conditioned in air (control) and in three different modified atmospheres (MAs) composed of 90% N2, 5% O2, 5% CO2 (A), 90% N2O, 5% O2, 5% CO2 (B) or 65% N2O, 25% Ar, 5% O2, 5% CO2 (C). The packed apple samples were stored at 4 °C for 12 days and pH, soluble solids content, weight loss, CO2 production, O2 consumption, texture changes, surface colour (whitening index, hue angle and chroma) and percentage of browning area were monitored. Beneficial effects of B and C MAP were found on enzymatic browning together with an increase of initial firmness and total soluble solid content. Atmospheres with high argon and nitrous oxide levels are shown some beneficial effect on the product quality during the 10 days period of storage, compared to control.
In this work different packaging strategies aimed to prolong the shelf life of minimally processed lampascioni are presented. In particular, two different treatments prior to packaging were tested: dipping in a solution containing citric acid (1%) and calcium chloride (8%), and coating with sodium alginate (5%), in combination with citric acid (1%) and calcium chloride solution (8%). The treated samples were packaged using two types of polymeric films: a commercially available oriented polypropylene film (OPP), and a polyester-based biodegradable film (NVT2). The investigated produce was stored at 5 °C for approximately 20 days. Microbial populations, pH, weight loss and visual quality were monitored for the entire observation period. In order to determine the respiration activity, O2 and CO2 concentration were monitored not only in OPP and NVT2 packages but also in the headspace of an aluminum-based package. Results show that, among the packaging strategies investigated in this work, the coated lampascioni packaged in NVT2 film were best preserved over the entire storage period. In fact, the alginate coating, combined with the gas barrier properties of the NVT2 film, can delay the lampascioni respiratory activity and the browning process, as well as the microbial growth, allows prolonging the shelf life of the investigated fresh-cut produce.
Mango pulp is very perishable and so has a short shelf life, which both marketers and consumers would like to be longer. Manually sliced mango was treated with aqueous solutions of 0%, 0.5%, 1% or 2% chitosan; placed into plastic trays, and over-wrapped with PVDC film and then stored at 6 °C. Changes in the sensory qualities of taste, color and water loss, were evaluated. A chitosan coating retarded water loss and the drop in sensory quality, increasing the soluble solid content, titratable acidity and ascorbic acid content. It also inhibited the growth of microorganisms. The data reveal that applying a chitosan coating effectively prolongs the quality attributes and extends the shelf life of sliced mango fruit.
Chemical fungicides provide the primary means for controlling postharvest fungal decay of fruit and vegetables. Continuous use of fungicides has faced two major obstacles—increasing public concern regarding contamination of perishables with fungicidal residues, and proliferation of resistance in the pathogen populations. The ultimate aim of recent research in this area has been the development and evaluation of various alternative control strategies to reduce dependency on synthetic fungicides. Several non-chemical treatments have been proposed for fungal decay control. Although these approaches have been shown to reduce postharvest rots of fruit and vegetables, each has limitations that can affect their commercial applicability. When used as stand-alone treatments, none of the non-chemical control methods has been clearly shown to offer a consistently economic level of disease control that warrants acceptance as an alternative to synthetic fungicides. Recently, the exploitation of natural products to control decay and prolong storage life of perishables has received more and more attention. Biologically active natural products have the potential to replace synthetic fungicides. This review deals with exploitation of some natural products such as flavour compounds, acetic acid, jasmonates, glucosinolates, propolis, fusapyrone and deoxyfusapyrone, chitosan, essential oils and plant extracts for the management of fungal rotting of fruit and vegetables, thereby prolonging shelf life.
Interest in the use of active and intelligent packaging systems for meat and meat products has increased in recent years. Active packaging refers to the incorporation of additives into packaging systems with the aim of maintaining or extending meat product quality and shelf-life. Active packaging systems discussed include oxygen scavengers, carbon dioxide scavengers and emitters, moisture control agents and anti-microbial packaging technologies. Intelligent packaging systems are those that monitor the condition of packaged foods to give information regarding the quality of the packaged food during transport and storage. The potential of sensor technologies, indicators (including integrity, freshness and time-temperature (TTI) indicators) and radio frequency identification (RFID) are evaluated for potential use in meat and meat products. Recognition of the benefits of active and intelligent packaging technologies by the food industry, development of economically viable packaging systems and increased consumer acceptance is necessary for commercial realisation of these packaging technologies.
Antimicrobial films were prepared by including enterocins to alginate, polyvinyl alcohol (PVOH), and zein films. The physical performance of the films was assessed by measuring color, microstructure (SEM), water vapor permeability (WVP), and tensile properties. All studied biopolymers showed poor WVP and limited tensile properties. PVOH showed the best performance exhibiting the lowest WVP values, higher tensile properties, and flexibility among studied biopolymers. SEM of antimicrobial films showed increased presence of voids and pores as a consequence of enterocin addition. However, changes in microstructure did not disturb WVP of films. Moreover, enterocin-containing films showed slight improvement compared to control films. Addition of enterocins to PVOH films had a plasticizing effect, by reducing its tensile strength and increasing the strain at break. The presence of enterocins had an important effect on tensile properties of zein films by significantly reducing its brittleness. Addition of enterocins, thus, proved not to disturb the physical performance of studied biopolymers. Development of new antimicrobial biodegradable packaging materials may contribute to improving food safety while reducing environmental impact derived from packaging waste.
Practical Application: Development of new antimicrobial biodegradable packaging materials may contribute to improving food safety while reducing environmental impact derived from packaging waste.
Due to increased demands for greater stringency in relation to hygiene and safety issues associated with fresh food products, coupled with ever-increasing demands by retailers for cost-effective extensions to product shelf-lives and the requirement to meet consumer expectations in relation to convenience and quality, the food packaging industry has rapidly developed to meet and satisfy expectations. One of the areas of research that has shown promise, and had success, is modified atmosphere packaging (MAP). The success of MAP-fresh meat depends on many factors including good initial product quality, good hygiene from the source plants, correct packaging material selection, the appropriate gas mix for the product, reliable packaging equipment, and maintenance of controlled temperatures and humidity levels. Advances in plastic materials and equipment have propelled advances in MAP, but other technological and logistical considerations are needed for successful MAP systems for raw chilled meat. Although several parameters critical for the quality of MA packed meat have been studied and each found to be crucial, understanding of the interactions between the parameters is needed. This review was undertaken to present the most comprehensive and current overview of the widely available, scattered information about the various integrated critical factors responsible for the quality and shelf life of MA packed meat with an interest to stimulate further research to optimize different quality parameters.
Postharvest browning of Agaricus mushrooms is a severe problem that reduces the shelf life of harvested mushrooms because of their continued respiration and biochemical activity. There are no simple answers and no single treatment is known to limit overall quality deterioration. However, there are several strategies that are being implemented in order to reduce the rate of respiration for mushrooms. Packaging technology is the common denominator that allows us to implement these strategies and thus is key to quality preservation. In this review, first, the major factors involved in postharvest quality deterioration are discussed and then technological advances/methods used to counteract these hurdles are presented.
Biodegradable poly(butylene adipate-co-terephthalate) (PBAT) films incorporated with nisin were prepared with concentrations of 0, 1000, 3000, and 5000 international units per cm(2) (IU/cm(2)). All the films with nisin inhibited Listeria innocua, and generated inhibition zones with diameters ranging from 14 to 17 mm. The water vapor permeability and oxygen permeability after the addition of nisin ranged from 3.05 to 3.61 x 10(11) g m m(-2) s(-1) Pa(-1) and from 4.80 x 10(7) to 11.26 x 10(7) mL.m.m(-2).d(-1).Pa(-1), respectively. The elongation at break (epsilon(b)) was not altered by the incorporation of nisin (P > 0.05). Significant effect was found for the elastic modulus (E) and the tensile strength (sigma(s)) (P < 0.05). The glass transition and melting temperatures with the presence of nisin ranged from -36.3 to -36.6 degrees C and from 122.5 to 124.2 degrees C, respectively. The thermal transition parameters such as the crystallization and melting enthalpies and crystallization temperature were influenced significantly (P < 0.05) by incorporation of nisin into films. The X-ray diffraction patterns exhibited decreasing levels of intensity (counts) as the concentration of nisin increased in a range of 2theta from 8 degrees to 35 degrees . Formation of holes and pores was observed from the environmental scanning electron microscopy images in the films containing nisin, suggesting interaction between PBAT and nisin.
Interactions between packaging materials and foodstuffs can affect food quality, e.g. on flavour aspects. There are three main phenomena: migration, permeation and absorption.
Several flavour compounds of an artificially flavoured drink yoghurt were absorbed by its high density polyethylene bottle. Selective absorption can disturb the delicate balance of flavour compounds and the product does not reach the consumer as was intended by the manufacturer.
Flavour change of mineral water packed in low density polyethylene lined aluminium/cardboard packages was studied by ombined gas chromatography and sniffing port analysis. Mainly aromatic hydrocarbons and some carbonyls appear to be responsible for the main sensory descriptors: metallic, musty, astringent, sickly, synthetic and glue-like.
Taste recognition threshold concentrations of styrene were determined in oil in water emulsions with different amounts of fat. Thresholds increased linearly with the amounts of fat in the emulsions. Moreover, the concentrations of styrene in the head spaces of the emulsions were similar at their threshold levels.
Essential oils (EOs) derived from plants are rich sources of volatile terpenoids and phenolic compounds. Such compounds have the potential to inactivate pathogenic bacteria on contact and in the vapor phase. Edible films made from fruits or vegetables containing EOs can be used commercially to protect food against contamination by pathogenic bacteria. EOs from cinnamon, allspice, and clove bud plants are compatible with the sensory characteristics of apple-based edible films. These films could extend product shelf life and reduce risk of pathogen growth on food surfaces. This study evaluated physical properties (water vapor permeability, color, tensile properties) and antimicrobial activities against Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes of allspice, cinnamon, and clove bud oils in apple puree film-forming solutions formulated into edible films at 0.5% to 3% (w/w) concentrations. Antimicrobial activities were determined by 2 independent methods: overlay of the film on top of the bacteria and vapor phase diffusion of the antimicrobial from the film to the bacteria. The antimicrobial activities against the 3 pathogens were in the following order: cinnamon oil > clove bud oil > allspice oil. The antimicrobial films were more effective against L. monocytogenes than against the S. enterica. The oils reduced the viscosity of the apple solutions and increased elongation and darkened the colors of the films. They did not affect water vapor permeability. The results show that apple-based films with allspice, cinnamon, or clove bud oils were active against 3 foodborne pathogens by both direct contact with the bacteria and indirectly by vapors emanating from the films.