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A novel two-stage process for the production of enzyme-modified cheese
Abstract
A novel method to generate enzyme-modified cheese (EMC) was developed. Initially a range of proteolysed products were produced from flavourless curd substrate using combinations of proteinases and peptidase hydrolysed to a set level of primary proteolysis. One product was selected based on ranked sensory preference analysis and subsequently further hydrolysed to a set degree of lipolysis using various lipases to create a selection of EMC products. These EMCs were compared to a target commercial Cheddar-type EMC, deemed to have a flavour profile close to natural Cheddar cheese. The sensory profile of each EMC generated were similar and not unlike the target EMC, however, greater diversity of flavour may be achieved by reducing the extent of lipolysis and/or increasing levels of free glutamate. The process demonstrates the potential to create a wide range of enzyme-modified cheese flavours from a single substrate using combinations of enzymes under controlled conditions.
... Previous literature reported EMC based on commercial cheddar cheese, the authors studied the compositions, proteolytic, lipolytic, and glycolytic indices of cheddar cheese, then used a novel two-stage process to produce EMCs, and produced EMC like commercial product flavor [11][12][13]. Similar research for EMC with cheesy flavor was developed [5]. ...
... Bas et al. (2019) hydrolyzed the slurry with Neutrase and Flavourzyme for 12 h and obtained approximately 80% pH 4.6-WSN/TN%. While this value was much higher than in previous studies (roughly 50%) which used other proteases [5,13]. It was speculated that the extent of proteolysis could be increased by using Flavourzyme. ...
... Subsequently, the blend was cooled to 54 • C and dispensed 4 kg into sterile containers for enzyme hydrolysis. Proteolysis was followed by lipolysis [13,15]. ...
(1) Background: to date, a clear description of the impact of specific enzymes on the enzyme-modified cheese (EMC) flavor is lacking. Moreover, comparative studies on the aroma compounds’ intensity of EMC have been rarely investigated. Therefore, this study was done to determine the influence of incubating substrates with proteases and different lipases on cheese ripening index and aroma compounds. (2) Methods: two-stage processing was adopted; proteolysis followed by lipolysis. (3) Results: results showed that the usage of Flavourzyme may improve the value of pH 4.6-WSN/TN%. Butanoic acid and hexanoic acid have a significant influence on the overall flavor of EMCs. In particular, the ethenyl acetate compound was detected in all products and was perceived as a fruity and sweet aroma, which has not been reported in previous literature. The concentration of short-chain fatty acids of EMCs made by Lipase MER was higher than EMCs made by Palatase, while the total content of medium and long-chain fatty acids of EMCs made by Lipase MER was lower than EMCs made by Palatase. The percentage of esters compounds in EMCs made by Lipase AY 30G was higher than the other two lipases, except EMC1. (4) Conclusions: Flavourzyme may be used to speed up the ripening of cheeses that need extensive proteolysis. The ability of Lipase MER to hydrolyze short-chain fatty acids was stronger than that of Palatase, while the ability of Lipase MER to hydrolyze medium and long-chain fatty acids was weaker than that of Palatase. The use of Lipase AY 30G was accompanied by the production of some other flavor esters, which made the final hydrolysates more fragrant and may be a good choice to produce fruity cheese flavor EMC. While Lipase MER may barely contain ester activity. This study may provide a reference for the selection of incubated enzymes for specific flavor EMC.
... A two-stage process in which proteolysis is followed by lipolysis was developed for EMC production by Kilcawley et al. (2006). They used this production procedure to obtain a specific cheese flavour (Cheddar) which is available in the market as EMC and the studies were carried out to reach the properties of the existing EMC product. ...
... A two-stage process procedure for EMC production was followed (Bas et al., 2019;Kilcawley et al., 2006). At the beginning of the production, cheese slurry with 25% dry matter content was prepared from the fresh white cheese in order to form a homogeneous substrate for the enzyme activation. ...
... In the second stage of EMC production, four different commercial lipases and three incubation times (24, 36, and 48 h) were investigated, while other parameters such as enzyme concentration, incubation temperature and shaking speed were kept constant. The enzyme concentration was determined according to the technical specifications of enzymes, the recommendations of the enzyme producers or literature and the observations of some preliminary productions (Haileselassie et al., 1999;Kilcawley et al., 2006). 2.0% Palatase ® 20000 L, 1.0% Piccantase ® A, 0.1% Lipomod TM 801MDP, 0.05% Lipomod TM 34MDP were individually added to the proteolysed slurry. ...
Enzyme-modified cheeses (EMCs) have been used uniquely to enhance the cheese flavour in processed foods. In this paper, effects of lipolytic enzymes during EMC production were investigated. EMC with ripened white cheese flavour was produced by a two-stage process in which proteolysis is followed by lipolysis. The results of proteolysis as the first stage were discussed in our previous report (Bas et al., 2019). In the present paper, four different commercial lipolytic enzymes with 3 different incubation times were applied to reach the target ripened white cheese flavour and free fatty acid (FFA) profiles, volatile compounds and sensory properties were investigated and the relationships between these properties were evaluated. Results showed that a balance in FFA profile is important. Samples contained nearly 19% butanoic acid in total volatiles and in the range of 10.7-12.3% volatile FFA in total FFA were desirable. During lipolysis, 17 new volatiles were formed, and most of the acids and esters among them are compounds commonly found in ripened white cheese. Moreover, absence of n-aldehydes was desirable for ripened white cheese flavour and lipolysed samples did not contain n-aldehydes. Briefly, lipolysis is critical in the formation of ripened white cheese flavour and two different enzyme-incubation time combinations (24 h with Piccantase® A and 48 h with Lipomod™ 801MDP) were suggested to use in the production of EMC with ripened white cheese flavour.
... Enzyme-modified cheeses (EMCs) are concentrated cheese flavours and are natural in origin. Production of EMCs is a process manufactured by mixing raw cheese curds, water, low fat, proteins and salts into a homogeneous paste in conjunction with the thermal energies and proteinase/peptidase and/or lipase digestion (El-Bakry et al. 2011;Kilcawley et al. 2006;Miri and Najafi 2011). EMCs production technology provides minimized preparation time, a cost-effective alternative to natural cheeses, a high degree of cheese flavour intensity, extended product shelf life and a boarder choice for customers (Wilkinson et al. 2011). ...
... However, despite economic importance there is a lack of detailed studies on the types of enzymes used and their specificities, enzyme dosage levels, curd substrate characteristics and process optimization (Miri and Najafi 2011; Wilkinson et al. 2011). EMC variants of many natural cheeses, such as Cheddar, Danish, Romano, Parmesan, Colby, Camembert, Mozzeralla, Brick and Emmental have been developed, which are commercially available with differing in flavour intensity (Kilcawley et al. 1998(Kilcawley et al. , 2006(Kilcawley et al. , 2012Miri and Najafi 2011;Wilkinson et al. 2011). However, studies regarding to optimization of the production of enzyme modified white cheese (EMWC) flavours combined with low fat addition are relatively scarce. ...
... Lipolysis was carried out at 45°C, 24 h, 500 rpm and terminated at 80°C for 20 min; finally the products were stored at -18°C for further analysis. The rationale behind the enzyme concentration levels, choice of incubation temperature, time and agitation speed for the proteolysis and lipolysis phases were selected based on the enzymes activity according to manufacturer's guidelines and literature surveyed (Kilcawley et al. 1998(Kilcawley et al. , 2002(Kilcawley et al. , 2006Amighi et al. 2016). ...
Enzyme modified white cheese (EMWC) was produced to use as flavouring ingredient. White cheese curd coupled with low fat was hydrolysed using combination of proteinases/peptidase to produce a range of proteolysed products followed by lipolysis. The results revealed that lowering pH 5.6 known to impart flavour strength of cheese. The inclusion of enzyme preparations significantly elevated free amino acids and free fatty acids. Developed EMWC had relatively higher levels of volatiles and improved sensory characteristics including less negative attributes such as, astringent, bitter, pungent, rancid, smoky, and more positive attributes, such as the strength of buttery, sweaty, caramel and nutty notes. Spray-dried EMWC powders had low moisture content and water activity values whereas, scanning electron micrographs showed spherical with a uniform distribution and large microparticles size. Because consumers like low fat products with cheese flavour, EMWCs are important products. Thus, process demonstrates the potential to be a cost-effective to produce EMWC flavour as ingredient and may suited to the products in which added.
... Ancak, hem peynir lezzetinin kompleks yapısından, hem de üretim tekniklerinde karşılaşılan sorunlardan ötürü doğal olmayan peynir lezzetlerinin üretimleri oldukça zordur ve maliyetleri de oldukça yüksektir. Buna ek olarak, "doğal" ürünlere yönelik ilginin son yıllarda artması, doğal lezzet katkılarının kullanılmasını ön plana çıkartmaktadır [3]- [5]. Peynir lezzeti sağlayan doğal katkı maddeleri, peynir tozları ve enzim modifiye peynirler (EMP) olmak üzere iki temel grupta toplanabilirken; tereyağı lezzeti sağlayan katkı maddeleri ise krema/tereyağı tozları ile enzim modifiye tereyağları (EMT) olarak yer almaktadır [1], [6]- [8]. ...
... Piyasada çeşitli EMP'lerin bulunmasına karşın, bu ürünleri bileşim ve proteolitik parametrelerine dair literatürdeki ilk çalışmalara son 20 yılda rastlanmaktadır ve bu çalışmalar da Cheddar lezzetli EMP'lere odaklanmıştır [11]. Aradan geçen 20 yılda Cheddar lezzetli EMP'lerin üretimine ve karakterizasyonuna dair kimi çalışmalar yapılmış olmasına karşın [5], [12], [13], diğer peynir lezzetleri incelenmemiş ve ülkemizde de herhangi bir çalışmaya rastlanmamıştır. Literatürde EMP üretiminde proteaz, peptidaz, lipaz ve esteraz enzimlerinin kullanıldığı ve bunların hemen hemen tamamının hayvansal ya da mikrobiyal kökenli olduğu belirtilmektedir. ...
... Ticari olarak piyasada bulunan Cheddar lezzetine sahip EMP'lerin bileşimi ve olgunlaşma özellikleri ile ilgili yapılmış bir çalışmada, Cheddar peynirinin kendisinin OUİ değerleri %13.1-28.4 aralığında değişirken, ticari EMP'lerde bu değer %26.8-84.6 aralığında değişmiştir [5], [11]. Aynı çalışmada, SAİ değerleri ise Cheddar peynirinde %1.4-7.5 aralığında değişirken, ticari EMP'lerde %5.3-65.5 aralığında belirlenmiştir [5], [11]. ...
... Products were analysed for moisture, protein, fat, ash and salt using IDF standard methods as described by Kilcawley, Wilkinson, and Fox (2006). The pH of slurry prepared by dispersing 10 g of each sample with 10 ml of deionised water was measured using a pH meter. ...
... Twenty trials at each stage were carried out in triplicate. The SC-EMC paste preparations were optimized using the following independent variables: Flavourzyme (1-2 g/kg)/Peptidase R (0.3% w/w) concentration (X 1 ), incubation temperature (40-60°C) (X 2 ), and time (6-45 h) (X 3 ), which were selected based on a literature survey (Amighi et al., 2013(Amighi et al., , 2016Kilcawley et al., 1998Kilcawley et al., , 2006. The PTA-SN, ACE-inhibitory activity and IC 50 values were the response (Y) variables. ...
... Cheese slurry (pH 6.8, 53.4% moisture, 43.5% fat, 3Á7% ash, 27.1% protein, 3.4% NaCl) was used to produce SC-EMC in a two-phase process as previously described (Kilcawley et al., 2006). In the first phase Flavourzyme Ò was incorporated into the slurry at several dosage levels (Table 1) in combination with Peptidase R (0.3%, w/ w) under the process incubation conditions (45°C, 24 h, 500 rpm). ...
In present study, we developed and optimized soymilk-cow’s milk enzyme-modified cheese with angiotensin-I converting enzyme inhibitory activity. Bioactive peptide production was found to be a multivariable-dependent process. Maximum bioactivity of hydrolysates was obtained with prolonged curd proteolysis at an increased enzyme concentration. This bioactive cheese paste was subsequently spray-dried under different drying conditions to determine the powder sorption isotherm properties. Higher drying temperatures resulted in cheese powder with weak thermal stability and lower browning indices. Experiments aimed at optimizing thermal stability and physical properties revealed that optimal conditions for producing cheese powder were an inlet air temperature of 150 °C, a feeding rate of 10%, and an air flow rate of 600 L h−1. Moreover, in addition to flavour, the bioactive cheese powders produced from a combination of soymilk-cow’s milk are of potential source and can be used in the dietary management of hypertension.
... To date, the published studies have only evaluated the effects on texture and structural characteristics of the products. One of the most used methodologies to overcome this problem is treatment of cheese curd with exogenous enzymes to generate flavoured potentiators, also known as enzyme-modified cheese (EMC), which has 15-30 fold higher flavour intensity (Wilkinson et al. 1992;Kilcawley et al. 1998Kilcawley et al. , 2002Kilcawley et al. , 2006. EMCs are developed using curd slurry techniques in powder or paste form, which deliver intense flavours, useful for the inclusion into a range of processed foods. ...
... (0.03%w/w) + PeptidaseR (0.3%,w/w) P-3 P-1 P-2 P-4 P-5 (a) Dosage levels, incubation temperature, time, and agitation speed for the proteolysis and lipolysis phases were selected based on the literature (Kilcawley et al. , 2006, as well as the supplier descriptions. ...
... The total N content of each pH 4.6-WSE samples was determined in triplicate by the macro-Kjeldahl method (IDF 1986a) to obtain the levels of pH 4.6-soluble nitrogen (pH 4.6-SN). The peptide profile of each pH 4.6-WSE was determined by Reverse Phase HPLC (RP-HPLC) using a Nucleocil C8 column at the wavelength of (214 nm) following Kilcawley et al. (2000) and Kilcawley et al. (2006). ...
Combined use of soymilk–cow’s milk is a novel approach in food industry and has great potential to developed products with numerous health benefits. This study aimed to develop the enzyme-modified cheeses (EMCs) using soymilk–cow’s milk. The curd was hydrolysed using combination of proteinases/peptidase to produce a range of proteolysed products followed by lipolysis to create flavoured EMCs. Results showed that enzymes led to an increase in amino acids (AA), free fatty acids (FFA), complex volatiles, and improved sensory attributes. The EMCs showed higher mean values of AA, FFA and volatile compounds when prepared using Flavourzyme® in combination with Lipases AY30 and DF15. EMCs were less eggy, bitter, pungent, more buttery, saltier, nutty, and had sweet sensory characteristics. Overall, results demonstrated the potential of combined matrix to create a range of flavoured EMCs for a wider range of consumers.
... Ancak, hem peynir lezzetinin kompleks yapısından, hem de üretim tekniklerinde karşılaşılan sorunlardan ötürü doğal olmayan peynir lezzetlerinin üretimleri oldukça zor ve maliyetleri de oldukça yüksektir. Buna ek olarak, "doğal" ürünlere yönelik ilginin son yıllarda artması, doğal lezzet katkılarının kullanılmasını ön plana çıkarmaktadır [9][10][11][12]. Peynir lezzeti sağlayan doğal katkılar, peynir tozları ve enzim modifiye peynirler (EMP) olmak üzere temelde iki grupta toplanmaktadırlar [5][6][7][8]. ...
... Standart ürün eldesinde problemler yaşanabilmekte ve lezzette farklılık sağlayabilmek için yapılabilecekler öngörülememektedir. Bu nedenlerden ötürü, farklı üretim teknikleri geliştirilmiştir [7,11]. Bu üretim tekniklerinden birisinde, lipoliz ve proteoliz farklı hammaddelerde ayrı ayrı gerçekleştirilmektedir. ...
... Buna göre, krema veya sadeyağın lipolizi ile elde edilen lipolize süt yağı ile taze peynirin proteolizi ile elde edilen ara ürün, farklı oranlarda karıştırılarak istenilen lezzette EMP üretilmektedir [10,20]. Şekil 1b'de gösterilen diğer bir yöntemde ise taze peynir kontrollü koşullarda, sırasıyla proteoliz ve lipolize uğratılmaktadır [7,11]. ...
Peynir, gıda tedarik zincirinin en büyük ve önemli parçasını oluşturan süt sektörünün, hem ürün çeşitliliği, hem kullanım yaygınlığı, hem de lezzet yoğunluğu açısından en dikkat çekici ürünüdür. Dünyada tüketilen sütün yaklaşık %40'ının peynir üretiminde kullanıldığı düşünülmektedir. Günümüzde ise, üretilen peynirlerin önemli bir bölümü, başka gıdaların üretiminde formülasyona katılan bir katkı olarak tüketilmektedir. Gıda katkısı olarak peynirlerin kullanımının temel nedeni lezzetleridir. Peynirlerin özgün lezzeti üretim sonrasındaki olgunlaşma sürecinde oluşmaktadır. Bu süreç oldukça maliyetli ve standardize edilmesi güç bir süreçtir. Olgunlaşma sürecinin kontrollü koşullarda, enzimatik reaksiyonlarla taklit edilmesi ile peynir lezzetinin geliştirilmesi ve yoğunlaştırılması, çok daha kısa sürelerde mümkün olabilmektedir. Bu yöntemle elde edilen ürüne enzim modifiye peynir (EMP) denilmektedir. EMP özellikle toz formda üretildiğinde, düşük maliyetli, dayanıklı, endüstriyel üretim ve tüketime uygun, standart üretimi kolay bir lezzet katkısıdır. Bu derlemede, lezzet katkısı olarak üretilen EMP'ler anlatılmış ve bu alanda yapılmış çalışmalar paylaşılmıştır.
ABSTRACT Dairy industry is the most important and biggest part of food supply chain. Among dairy products, cheese is the most remarkable product due to its variability, high market coverage and flavor. About the 40% of the total milk produced worldwide is used for cheese production, and an important ratio of this production is used as an ingredient for the production of other foods. The main reason for its use as an ingredient is its flavor. Unique flavor of cheese is developed during ripening period. Ripening is a high-cost process, and standardization of the product is not easy. It is possible to develop and intensify cheese flavor in a short time under controlled conditions by the aid of enzymatic reactions. The product obtained with this method is called enzyme modified cheese (EMC). Especially in a powder form, EMC is a low-cost, stable, easy to use and standard flavor ingredient with consistent cheese flavor. In this present study, EMCs produced as a flavor ingredient and studies on this topic are reviewed.
... There are several papers published in the literature on the characterisation of EMCs (Kilcawley, Wilkinson, & Fox, 2000, 2001Salum, Erbay, & Selli, 2019). Studies in the literature on EMC production were related to the effects of production methods, processing conditions, product formulation, and/or the use of different enzymes on the final product (Ali et al., 2019;Gao et al., 2022;Kilcawley, Wilkinson, & Fox, 2006;Lee et al., 2007). Our research group determined the appropriate formulation and process conditions for each stage of EMC production and produced a liquid EMC with a ripened white cheese flavour in previous studies (Bas, Kendirci, Salum, Govce, & Erbay, 2019;Kendirci, Salum, Bas, & Erbay, 2020). ...
... Production procedure 2.2.1. Liquid enzyme-modified cheese production A two-stage process for EMC production was used (Kilcawley et al., 2006). At the beginning of the production, cheese slurry with 25% dry matter content was prepared from the fresh white cheese to form a homogeneous substrate for the enzyme activation using trisodium citrate and trisodium phosphate as emulsifying salts and potassium sorbate as a preservative. ...
... A two-stage process was developed by Kilcawley, Wilkinson, and Fox (2006) for the production of EMC in which proteolysis and lipolysis were sequentially applied. In our previous work, we have applied the same procedure for the production of EMC with ripened white cheese flavour which is not commercially available and optimised the production conditions to fill the gap in the market (Bas, Kendirci, Salum, Govce, & Erbay, 2019;Kendirci, Salum, Bas, & Erbay, 2020;Salum, Govce, Kendirci, Bas, & Erbay, 2018). ...
... In the EMC production, a two-stage production technique was applied as described by Kilcawley et al. (2006). After the processing of raw material (fresh cheese) with emulsifying salts, proteolysis was performed in the first stage and then lipolysis was applied in the second stage. ...
Enzyme-modified cheese (EMC) is a flavour ingredient with intense cheese flavour and can be produced in both liquid and powder form. In this study, the effects of spray drying process conditions (inlet temperature, feed flow rate, air flow rate) on the quality parameters of EMC powder (compositional, physical, and morphological properties) were investigated. Additionally, the variations in the free fatty acids and volatile compounds were assessed. The results showed that higher drying yields and desirable physical properties (flowability, wettability, bulk density, and colour) were obtained at low drying rates. Moreover, detection of volatile compounds (n-aldehydes and methyl ketones) at higher spray drying rates indicated fat oxidation. Reconstitution properties of the powders were dependent not only on the factors including surface fat of the powder and hydrophobicity of the powder surface, but also the other factors such as bulk density, particle agglomeration and porosity.
... Aromatic additives with a cheese flavor ("enzyme-modified cheese" -EMC) were produced according to the two-step approach method described in [12] with a number of modifications. A mixture was prepared from fresh cheese curd having a pH of 6.35 ± 0.05, Na caseinate, a complex phosphate additive "Phonakon" (Reatex, Russia) consisting of a mixture of phosphate saltsemulsifiers (E451i, E450i, E450ii, E339i, E339ii) and water. ...
... The hydrolysis products of casein, small peptides and free amino acids, have a pronounced taste and make a direct contribution to the formation of cheese flavor [19,20]. High levels of low molecular weight peptides and free amino acids (FAA) important in cheese flavor [12]. As a result of numerous studies, it was found that among the products of proteolysis, peptides with a mass of less than 0.5 kDa make the greatest contribution to the formation of the flavor of Cheddar cheese [17]. ...
The method based on the determination of the amount of active amino groups using o-Phthaldialdehyde (OPA method) can be applied in practice to assess accurately the degree of proteolysis in cheeses. The work establishes that the OPA method gives results that strictly correlate (R2 > 0.80, p < 0.01) with the results of assessing the degree of proteolysis by the Kjeldahl method. The results of the OPA method, expressed in the absorption intensity of the colored sample at a wavelength of 340 nm (OD340), can be converted to the content of soluble nitrogenous substances in cheese (WSN), using the calibration relationship between these indicators.
The accuracy of the calibration relationship between WSN and OD340 can be increased (R2 > 0.91, p< 0.01) when using the OPA method in relation to a homogeneous group of cheeses produced by the same technology using the same type of milk clotting enzyme and lactic acid starter culture and having a similar shape of the molecular mass distribution of proteolysis products.
The OPA method can be used to assess the content of proteolysis products, which form cheese flavor, in EMС. The results of assessing the degree of proteolysis by the OPA method (OD340) are proportional to both the total content of soluble nitrogen and the proportion of nitrogenous substances in it with a mass of less than 0.5 kDa, which make the greatest contribution to the formation of cheese flavor.
The advantage of using the OPA method for assessing proteolysis in cheeses and EMC instead of the Kjeldahl method is a simpler measurement procedure and the possibility of studying more samples in less time.
... Most of the information in the literature about the production of EMC with a specific cheese flavour is based on a series of studies published by Kilcawley et al. between 2000(Hulin-Bertaud et al., 2000Kilcawley et al., 2000Kilcawley et al., , 2001Kilcawley et al., 2006). The authors purchased and analysed Cheddar EMCs on the market and identified the best one with respect to their characteristic Cheddar flavour. ...
... For this purpose, 0.01% Neutrase, 0.05% Promod215, 0.03% Flavourzyme, 0.05% Flavorpro937 and 0.1% FlavorproUmami were individually added to the substrate. The enzyme concentrations were determined by using the technical specifications of the enzymes, recommendations of the enzyme producers or literature and observations of some preliminary productions (Haileselassie et al., 1999;Kilcawley et al., 2006). After the addition of enzymes, samples were placed in a shaking incubator (KS3000 IC, IKA ® -Werke GmbH & Co. KG, Staufen, Germany) and incubated at 45 • C with a speed of 250 rpm. ...
Enzyme-modified cheeses (EMCs) are used uniquely to enhance the cheese flavour in processed foods. Here we report, for the first time, the results from proteolysis process of the two-stage production of EMC with ripened white cheese flavour. Proteolytic ripening parameters, sensory properties, and volatile compounds were investigated to reach a target cheese flavour and the relationships between these properties were evaluated. Individual and combined effects of commercial proteolytic enzymes were studied and conditions for the production of EMC with ripened white cheese flavour were determined. Results showed the importance of phenol, 2-undecanone, and 3-methyl-1-butanol on cheese flavour strength and overall acceptability of EMC. Although a single parameter is not enough to evaluate the dynamic nature of the formation of bitterness, TCASN/WSN and PTASN/WSN ratios were suggested to be useful parameters in determining the appropriate degree of proteolysis and in evaluating the bitterness.
... Additionally, these processes are environmentally unfriendly and potentially costly (Longo and Sanroman 2006). Additionally, the increased interest in 'natural' products over the last few years has given rise to the use of natural flavour additives ( Kilcawley et al. 1998Kilcawley et al. , 2006). The natural additives that provide cheese flavour can be classified into two main groups as cheese powder and enzyme-modified cheese (EMC; Guinee and Kil- cawley 2004;West 2007;Erbay and Koca 2015). ...
... In these studies, characterisation of commercial Cheddar EMCs including glycolytic, lipolytic, proteolytic and sensorial properties was investigated (Hulin-Bertaud et al. 2000;Kilcawley et al. 2000Kilcawley et al. , 2001). Moreover, a two-stage EMC production technique was developed and the enzymes/process conditions were used to produce an EMC with similar properties to commercial Cheddar EMCs ( Kilcawley et al. 2006). Also, a recent study was carried out to produce an EMC product from the curd manufactured by a mixture of soymilk and bovine milk ( Ali et al. 2017). ...
Eight different commercial enzyme‐modified cheeses (EMCs) were analysed, and the distinctive/common features of the products and production methods were investigated. Results showed that the total free fatty acid contents of EMC samples were 10 to 100 times higher than the values reported for the related cheese varieties. A total of 37 volatile compounds were identified, and acids were found as the most dominant group in all EMC samples. While furan compounds and 2‐acetylpyrrole were most intensively detected in the goat cheese EMC, methyl ketones were found in the highest amounts in Blue cheese EMC.
... In the past few decades, special emphasis has been put in addition of cheese flavor to prepared foods due to consumer demand. The production of enzyme-modified cheese (EMC) is an economic and consistent method for enhancing cheese flavors in food products which require source of cheese such as Cheddar, Swiss, Blue, Romano, etc. (Hulin-Bertaud et al., 2000;Kicalwley et al., 1998Kicalwley et al., , 2006Moskowitz and Neolck, 1987). EMCs are manufactured through the addition of a complement of proteolytic and/or lipolytic enzymes to emulsions of natural cheese substrates (Kicalwley et al., 1998(Kicalwley et al., , 2006. ...
... The production of enzyme-modified cheese (EMC) is an economic and consistent method for enhancing cheese flavors in food products which require source of cheese such as Cheddar, Swiss, Blue, Romano, etc. (Hulin-Bertaud et al., 2000;Kicalwley et al., 1998Kicalwley et al., , 2006Moskowitz and Neolck, 1987). EMCs are manufactured through the addition of a complement of proteolytic and/or lipolytic enzymes to emulsions of natural cheese substrates (Kicalwley et al., 1998(Kicalwley et al., , 2006. Manufacturing process and selection of equipments for EMC production necessitates a complete attention to the details * Corresponding author. ...
In the food industry, there is an increasing emphasis on the need for an economic and an additional cheese flavor to prepared food. In this paper a Genetic Fuzzy Rule Base System (GFRS) for modeling of viscosity in enzyme-modified cheese (EMC) is described based on experimental data. Using data obtained via measurement of viscosity in EMC prepared with different dosage of a commercial bacterial neutral proteinase, Neutrase® 0.5L (0.00, 0.05, 0.10, 0.15, 0.20 and 0.25 v/w%) at 30, 40 and 50 °C with 100, 200 and 300 RPM in a viscometer, it is concluded that construction of an optimized fuzzy model for the evaluation of viscosity in EMC is a reliable procedure. This may help manufacturers to control the viscosity of EMS in processing units by selecting the appropriate combinations of potential manufacturing parameters.
... A two-stage production technique, as described by Kilcawley et al. (2006), was used to produce EMC. The raw materials (fresh white cheese (C), water, emulsifying salts, and preservative) were heated and processed with agitation to prepare processed cheese slurry (PC). ...
Milk proteins are a known source of bioactive peptides released through proteolysis. Enzyme-modified cheese (EMC), produced with high proteolysis levels, has the potential to provide such peptides. This study aimed to explore the bioactive potentials (antioxidant, antihypertensive, antidiabetic, antimicrobial, and antiproliferative potentials) of EMC during production stages and after in vitro digestion. Results showed remarkable increases in antioxidant activities and sustained ACE inhibition activity values with each production stage. The samples inhibited α-amylase activity before in vitro digestion, while significant inhibition of α-glucosidase activity was observed after digestion. Furthermore, antimicrobial effects on S. aureus were observed after digestion, with limited antiproliferative effects on various cancer cells. The study demonstrates the potential of EMC to positively impact body functions through its bioactive properties. Further research is needed to investigate the components formed during the production stages in detail.
... There are some studies that investigated the properties of EMCs which can be found commercially in the market (Erbay et al., 2017;Hulin-Bertaud et al., 2000;Kilcawley et al., 2000Kilcawley et al., , 2001Salum et al., 2019). Various studies were carried out on the production of EMCs with specific cheese flavors in liquid form, and all of them were conducted with a two-stage production technique (Ali et al., 2017a(Ali et al., , 2017bBas et al., 2019;Kendirci et al., 2020;Kilcawley et al., 2006). Studies on the conversion of EMC into powder are relatively new, and encapsulation studies have also just begun to reduce the flavor loss during spray drying (Ali et al., 2019;Amighi et al., 2013Amighi et al., , 2016Erbay et al., 2018;Salum et al., 2022). ...
... There are three main well-known EMC manufacturing approaches, namely: 1) one-stage process, which is based on simultaneous cheese curd proteolysis and lipolysis under controlled conditions; 2) a second process, according to which, proteolysis and lipolysis are individually carried out in different substrates (eg. butterfat/cream, for lipolysis; and cheese curd, for proteolysis); and 3) two-stage process, which uses a single stable substrate; it starts with proteolysis, which is followed by lipolysis (Bas et al., 2019;Kilcawley et al., 2006;). The one-stage process is the technique mostly used for commercial purposes among the aforementioned processes (Bas et al., 2019). ...
The dairy sector is one of the most important industrial segments in peptidase applications These enzymes can hydrolyze milk proteins into medium/short peptides and amino acids, as well as modulate their nutritional and functional properties, which comprise sensory changes (e.g., texture and flavor), digestibility and solubility improved, as well as the release of bioactive compounds. Therefore, they have been applied to develop different dairy products, such as cheese and a wide range of products deriving from caseins and whey proteins. However, it is important to understand the structure of milk proteins at the time to select the best peptidase to achieve the desired hydrolyzed products. In addition, peptidases have different specificities, such as catalytic sites and optimal pH, which must be taken into account before their application in the dairy matrix. The present review aims to address important aspects associated with peptidase features and their current biotechnological applications in the dairy industry.
... Özgün bir peynir lezzetinden ziyade genel bir peynirimsi lezzetin elde edilmesine çalışılan çalışmaların yanı sıra, Cheddar, olgun beyaz peynir, lighvan peyniri gibi birkaç özel peynir lezzetinin elde edilmesine yönelik çalışmalara literatürde rastlanmıştır. Bu alandaki temel çalışmalar İrlanda'daki bir araştırma ekibi tarafından gerçekleştirilmiş ve elde edilen sonuçlar bir dizi makalede basılarak paylaşılmıştır [32][33][34]41]. Bu çalışma dizisinde, Cheddar lezzetine sahip EMP üretimi hedeflenmiş ve bu amaçla öncelikle piyasada bulunan Cheddar lezzetine sahip ticari EMP'lerin özellikleri ayrıntılı olarak incelenmiştir. ...
Peynir lezzeti sağlayan katkılar, çeşitli gıdaların formülasyonlarında, peynir lezzeti vermek veya peynir lezzetini arttırmak için kullanılmaktadır. Gıda endüstrisinde ve bilimsel literatürde peynir lezzet katkılarına olan talep ve ilgi son yıllarda artış göstermektedir ve bunlar içerisinde en dikkat çekicisi enzim modifiye peynir (EMP)'dir. EMP, peynir lezzetini geliştirmek veya yoğunlaştırmak için taze peynirin kontrollü koşullarda enzimle işlenmesi sonucu elde edilen ürüne denilmektedir. EMP üretiminde peynirin taze hali veya pıhtısı homojen ve kararlı bir akışkana dönüştürülüp, dışarıdan ilave edilen proteolitik ve lipolitik enzimlerle işlenir ve daha sonra ısıl işlemle enzimatik reaksiyonlar durdurularak üretim tamamlanır. EMP üç farklı yöntem ile üretilebilmektedir: (1) tek hammaddeden, proteolizin ve lipolizin sırasıyla gerçekleştirildiği iki aşamalı üretim tekniği, (2) farklı hammaddelerde ayrı ayrı lipolizin ve proteolizin gerçekleştirilip, uygun oranlarda karıştırıldığı bileşen bazlı üretim yaklaşımı ve (3) tek hammaddede, tek aşamada, eşzamanlı proteoliz ve lipolizin gerçekleştirildiği tek aşamalı üretim tekniği. Tercih edilecek üretim tekniği ve üretim parametreleri, istenilen lezzette ve kararlılıkta bir EMP ürünü elde etmek için önem arz etmektedir. Bu çalışmada, doğal peynir lezzet katkısı olarak EMP açıklanmış, EMP üretimi ve üretim tekniklerine odaklanarak, literatür çalışmaları derlenmiştir.
... Yeast and mold fungi have the lowest minimum development temperatures (minus 2 ... minus 10 ºС), and at a rather low water activity. If at low temperatures yeast and mold are resistant and able to grow, then at the same temperatures mesophilic bacteria already die off or their vital activity slows down significantly [2,10,11]. In our opinion, it is advisable to consider the microbiological ...
... In previous studies on cheese, the commercial preparations Accelerzyme CPG V R , Debitrase DBP 20 and FlavoGard V R were shown to be appropriate for cheese flavour development, while acting in different ways on protein breakdown (Kilcawley et al., 2006(Kilcawley et al., , 2012. To the best of our knowledge, none of these products had been tested yet in dry fermented sausages with a high lactic derivatives content, which is a common composition in some Spanish fermented sausages (Gou et al., 1998) that increases sweetness, protein content and dry matter and provides slight lactic nuances. ...
This study investigated the impact of the addition of exogenous enzymes (Accelerzyme CPG, Debitrase DBP20) or cellular preparations (FlavoGard), traditionally used in the cheese industry, to accelerate flavour development of dry fermented sausages with 6% of lactic derivatives content. Sausages were fermented to pH 5.0, dried for 32 days and vacuum packed stored under refrigeration for 60 days. Sausages were analysed for physicochemical parameters, technological microbiota and proteolysis after fermentation, drying/ripening and storage. Similar compositional results were obtained in all products (38-39% humidity in the final product; 38.2% fat and 40.7% protein as dry matter throughout the study). Debitrase application positively affected proteolysis by changing the free amino acid profile and increasing non-protein nitrogen and total free amino acids by 2.2 and 11.8-fold, respectively. Accelerzyme increased ripened cheese flavour and overall sensory quality from 5.1 to 5.8; Debitrase increased ripened cheese odour and flavour, bitterness, umami, adhesiveness, pastiness, and overall sensory quality from 5.0 to 5.9, and decreased acid and hardness. This study highlights the effects of adding some exogenous enzyme/bacterial preparations traditionally used in the cheese industry to enhance the flavour of dry fermented sausages with high content of lactic ingredients and increase its sensory quality.
... Yeast and mold fungi have the lowest minimum development temperatures (minus 2 ... minus 10°C), and at a rather low water activity. If at low temperatures yeast and mold are resistant and able to grow, then at the same temperatures mesophilic bacteria already die off or their vital activity slows down significantly [2,10,11]. ...
... Based on advances in technology, new artifi- cial flavouring components receive a great deal of attention within the food industry, which has allowed consumers enjoy a diversity of dairy products ( Wang and Xu 2009). Moreover, because milk fat is a costly ingredient, there is an increased demand for low-cost dairy products and subsequently for strong synthetic flavours that can improve such products' consumer acceptability ( Kilcawley et al. 2006). ...
The combined effects of lipase/cream reaction, temperature/time and pH of fermentation on levels of free fatty acids (FFAs), biochemical changes, oxidative stability and flavour development of the dough during 21 days of cold storage were investigated. Levels of short‐chain FFAs increased in doogh samples, while long‐chain FFAs decreased. Under the severe conditions of the lipase/cream reaction, the lowest pH drop, acidity increase and the highest intensity of lipid oxidation were observed. Treatment with a shorter reaction time and a lower temperature of the lipase/cream mixture and a lower final pH of fermentation (4.0‐20‐30) achieved the highest sensory acceptability, which could be used to improve industrial doogh.
... Lipase enzyme with activity and stability at the wide range of temperature is favoring characteristic for detergent applications, at high temperatures due to their responses provides fewer microbial contamination threats, high solubility of substrates and low viscosity of the reaction elements [52]. At low temperature can accomplish with synthetic unstable compounds and improves oil elimination from fabric; consequently, reduces energy consumption [52][53][54]. According to test results, lipase of O. intermedium strain MZV101 had remained active and stable at temperature range of 4-90°C (Fig. 3). ...
Background
Alkaline thermostable lipase and biosurfactant producing bacteria are very interested at detergent applications, not only because of their eco-friendly characterize, but alsoproduction lipase and biosurfactant by using cheap materials. Ochrobactrum intermedium strain MZV101 was isolated as washing powder resistant, alkaline thermostable lipase and biosurfactant producing bacterium in order to use at detergent applications.
Methods
O. intermedium strain MZV101 produces was lipase and biosurfactant in the same media with pH 10 and temperature of 60 °C. Washing test and some detergent compatibility character of lipase enzyme and biosurfactant were assayed. The antimicrobial activity evaluated against various bacteria and fungi.
Results
Lipase and biosurfactant produced by O. intermedium strain MZV101 exhibited high stability at pH 10–13 and temperature of 70–90 °C, biosurfactant exhibits good stability at pH 9–13 and thermostability in all range. Both lipase and biosurfactant were found to be stable in the presence of different metal ions, detergents and organic solvents. The lipase enzyme extracted using isopropanol with yield of 69.2% and biosurfactant with ethanol emulsification index value of 70.99% and yield of 9.32 (g/l). The single band protein after through from G-50 Sephadex column on SDS-PAGE was calculated to be 99.42 kDa. Biosurfactant O. intermedium strain MZV101 exhibited good antimicrobial activity against Gram-negative bacteria and against various bacterial pathogens. Based upon washing test biosurfactant and lipase O. intermedium strain MZV101considered being strong oil removal.
Conclusion
The results of this study indicate that isolated lipase and biosurfactant with strong oil removal, antimicrobial activity and good stability could be useful for detergent applications.
Graphical abstract
... The level of pH 4.6-soluble cheese nitrogen (pH 4.6-SN), expressed as percentages of total nitrogen (TN), was measured as described by Fenelon et al. (2000b). Free amino acids (FAA) were determined on filtrates prepared by mixing equal quantities of 24% trichloroacetic and pH 4.6 soluble-SN extract, as described by Kilcawley et al. (2006). Supernatants were removed and diluted with 0.2 M sodium citrate buffer, pH 2.2 to give approximately 250 nmol of each amino acid residue. ...
Six leading brands of mature/vintage full-fat Cheddar cheese were procured from retail stores in Ireland and the UK on six separate occasions over a six-month period, and analysed for composition, proteolysis, lipolysis and sensory characteristics. The aim of the study was to assess the consistency of leading retail brands of vintage Cheddar cheese. Significant inter-brand differences were evident for gross composition, with the magnitude of the differences between means depending on the parameters: mean salt-in-moisture, S/M 4.18% to 5.74% (w/w); moisture-in-non-fat substances, MNFS 52.0% to 54.78% (w/w); fat-in-dry matter, FDM 50.0% to 52.63% (w/w); total lactate 1.06% to 1.46% (w/w); pH 5.09-5.38. The coefficient of variation (cv) of the mean of the six brand means indicated that this variation was highest for concentrations of L(+) and D(-) lactate (cv 25% and 50%) and S/M (cv ∼12%), and comparatively low (<5%) for MNFS, pH and calcium-to-protein ratio. Similarly, significant inter-brand variation was noted for degrees of proteolysis with the mean pH 4.6 soluble N varying from 28% to 34% of total N, total free amino (FAA) acids from 27,000 to 57,000 mg/kg, ratio of FAA nitrogen to pH 4.6 soluble N from 30% to 70%, and free fatty acids (FFA) from ∼900 to 1600 mg/kg. Intra-brand inconsistency in composition, and degrees of proteolysis and lipolysis were also notable, especially for concentrations of S/M (cv 4% to 20%), D(-) lactate (cv 30% to 110%), total FFA (cv 7% to 35%) and total FAA acids (cv 11% to 63%). Inter- and intra-brand variations in composition and biochemistry coincided with differences in aroma, flavour and texture attributes, and the scores for maturity and acceptability. Variations in milk composition, manufacturing conditions/technology, and added starter cultures/enzyme preparations are discussed as probable causes of the inconsistencies between and within brands.
... Individual free amino acids (FAA) were determined on 24% trichloroacetic acid filtrates prepared from the water-soluble nitrogen fraction using a Jeol JLC-500/V Amino Acid Analyzer (Jeol Ltd, Garden City, Herts, UK) fitted with a Jeol sodium high performance cation exchange column (Kilcawley et al., 2006) and the results expressed as μg/g cheese. All analyses were carried out in duplicate. ...
... The procedure may, however, result in hydrolysis and inactivation of the lipolytic enzyme(s) by accompanying proteolytic counterpart(s). Therefore, a multi-stage process initiated by proteolysis, mediated by heat treatment and finished by lipolysis has been developed (Kilcawley et al. 2006). Release of free fatty acids upon lipolysis contributes considerably to the flavour development in EMC (Noronha et al. 2008). ...
The proteolytic stage of the digestion process of white cheese curd was optimised to maximise the angiotensin I-converting enzyme (ACE)-inhibitory activity of the final enzyme-modified cheese (EMC) paste. It was found that bioactive peptides generation in EMC paste was of multi-variable dependent nature and could be optimised by targeted selection of specific component variables. Maximum ACE-inhibitory was obtained by proteolysis at 48 °C for 25 h with 1 g Flavourzyme/kg cheese curd. This bioactive EMC paste was subsequently spray-dried. The drying conditions were optimised to obtain a highly soluble powder to warrant quick and complete hydration, with the lowest water activity to maximise long term storage. The higher the inlet drying air temperature, the greater was the solubility of resultant EMC powder. Differential scanning calorimetry analysis revealed that the highest drying air temperature (200 °C) resulted in a lower glass transition temperature for the potentially bioactive EMC powder.
... In the latter, several different flavour components are created separately and then blended together (Kilcawley et al., 2000). A two-step process in which a flavourless cheese curd is initially proteolysed to a set degree and then further hydrolysed by lipase has been also introduced, favouring the production of wide range of cheese flavours from a single substrate (Kilcawley et al., 2005). The practical processing conditions depend upon many factors and directly relate to the enzymes being used. ...
An angiotensin-I converting enzyme (ACE)-inhibitory enzyme-modified cheese (EMC) was spray-dried at different inlet drying air temperatures, feeding pump rates and spraying air flow rates. Powder moisture content, bulk density, porosity, production yield and particles size were responses of interest measured. Response surface optimisation determined that if the cheese paste is pumped at feeding pump rate of 5%, sprayed with the compressed air at rate of 400 L h−1 and dried by an air at temperature of 154 °C, minimum moisture content is achieved for the produced powder. Spray drying decreased the ACE-inhibitory of EMC significantly, but the powder was still extremely bioactive. Scanning electron microscopy (SEM) images revealed that inlet drying air temperature of 150 °C yielded a powder with relatively well-separated particles. Higher drying air temperatures resulted in lower browning indices for the EMC powder.
... Individual free amino acids (FAA) were determined on 24% trichloroacetic acid filtrates prepared from the water-soluble nitrogen fraction using a Jeol JLC-500/V Amino Acid Analyzer (Jeol Ltd, Garden City, Herts, UK) fitted with a Jeol sodium high performance cation exchange column (Kilcawley et al., 2006) and the results expressed as μg/g cheese. All analyses were carried out in duplicate. ...
The use of recombinant aminopeptidase (PepN) from Lactobacillusrhamnosus S93 in free or encapsulated form was investigated to shorten the duration of Cheddar cheese ripening. Proteolysis was determined by measuring the soluble nitrogen as phosphotungstic acid (PTA-N) derivatives and free amino acids (FAA) over a 6-month period. The experimental cheeses received higher scores for sensory properties than the control cheese. The amounts of PTA-N and total FAA in the cheese with the encapsulated enzyme after 2 months of ripening were close to those of the control cheese after 6 months, suggesting the acceleration in proteolysis by about 4 months.
... Th e method was adopted by the International Standards Organization [32]. Th is method was successfully used to quantify levels of lipolysis in enzyme-modifi ed cheese samples [33] where values up to 22.8 ADV units were found. ...
... Enzyme-modified cheeses (EMCs) are concentrated cheese flavours produced enzymatically from dairy substrates and are designed to provide a concentrated source of cheese flavour (Kilcawley et al. 2006;Noronha et al. 2008). ...
The influence of enzyme-modified cheese (EMC) and fat content on sensory and texture properties of cream cheese was investigated. Enzyme-modified cheese and fat content were set at three levels each, and organoleptic and texture properties for all experimental cheeses were then determined. Data were analysed using response surface methodology. Both design parameters had significant influence on sensory and texture properties. The EMC did not alter hardness significantly, whereas the higher fat formula had the higher hardness. The results indicated that the optimum level of EMC was less than 1% for high-fat cream cheeses and at least 5% for low-fat cream cheeses.
... EMC powder; McSweeney, 2007). Volatile fatty acids are the major contributors to the flavour of EMCs and the resulting blended processed cheese products (Kilcawley et al., 2006). Each short-and intermediate-chain fatty acid may have their typical share of the flavour. ...
IntroductionTypes of processed cheeseRaw materialFlavourColoursSensory attributes of processed cheeseConclusion
References
Enzyme-modified cheese (EMC) produced by enzyme hydrolysis is a natural, cost-effective, and flexible alternative to using natural cheese in industrial applications. The modification of cheese by enzymes can increase their benefits for consumer acceptance and health, and intensify the specific cheese flavor. We evaluated the properties of cheese with added protease (Ep) or lipase (El), including texture, sensory, organic acids, volatile compounds, and free amino acids. As results, the hardness and gumminess of the cheese reached their maximum values when the concentration of protease and lipase was 0.1% and 0.6%, respectively. Interestingly, the bitterness and astringency of the cheese was reduced. The highest scores for odor, taste, and overall acceptability were observed on 0.08% protease in Ep and 0.8% lipase in El. Compared with the anchor cheese, eight new compounds were produced after the addition of protease and nine new compounds were produced after the addition of lipase. Irrespective of the type of enzyme, the content of free amino acids decreased slightly with the increase in enzyme content. From the point of view of adding enzyme species, the free amino acids content of Ep was generally higher than that of El, and glutamic acid and proline contents were high. Acetic acid concentrations (aroma-active compounds) of enzyme-modified cheese using protease and lipase were 482-931 mg/100 g and 30-36 mg/100 g, respectively, which were significantly increased. According to the results obtained in this study, a cheese with higher sensorial and textural acceptability was obtained by adding the appropriate protease or lipase.
Enzyme-modified cheese (EMC) is a concentrated cheese flavor that is produced enzymatically from dairy substrates to provide an intense source of cheese flavor with broad applications. In this study, EMC was produced by enzymatic biotransformation from a new bacterial isolate described and molecularly identified as Bacillus thuringiensis strain-MA8. Optimization of protease production conditions using one-variable-at-a-time followed by multi-factorial (Plackett-Burman and Box-Behnken) designs increased production by 7-fold. Protease was used at different concentrations (300 and 900 U/100 g curd) as a cost-effective source of concentrated cheese flavor in the EMC preparation. Sensorial evaluation of EMC revealed that the overall acceptability, flavor, and texture were improved from the 2nd day compared to the control, and then decreased on the 4th day without any apparent bitterness. The chemical characteristics of EMC showed that the addition of protease extracts increased the total volatile fatty acids, water-soluble nitrogen, and acidity of EMC significantly (p ≤ 0.05) compared to the control. The amino acids profile revealed that EMC1 which was treated with (300 U/100 g curd) protease had the highest essential amino acids (EAA) and EAA/total amino acids ratio. Nutritional parameters including protein efficiency ratio, biological value, and chemical score of EMC were higher than control based on Val, Met + Cys, Ile, Leu, and Phe + Tyr amino acids. Also, Scanning Electron Microscopy showed significant changes in EMC compared to the control. In conclusion, the addition of (300 U/100 g curd) of protease revealed good EMC characteristics without any apparent defect.
This study aimed to improve the bread quality, especially aroma, using the fermented cream-soy protein isolate (SPI) flavor and reveal the improvement mechanisms. The cream with partially substituted SPI was fermented by lactic acid bacteria to enhance its flavor and used for bread making. The study also explored the positive effect of fermented cream on bread quality, especially the aroma formation. The bread quality was assessed by sensory evaluation, texture, and color determination, and the changes in bread dough characteristics were evaluated using a rheofermentometer and a dynamic rheometer. Furthermore, the influence of fermented cream-SPI flavor on bread volatile compounds (VOCs) was investigated using gas chromatography–mass spectrometry and principal component analysis. The results showed that the fermented cream-SPI flavor improved the texture of bread by increasing the gas production and the gluten strength of the dough. It reduced the crumb hardness from 337 ± 12 g to 171 ± 6 g and increased the specific volume from 3.51 ± 0.05 g/mL to 4.19 ± 0.06 g/mL. Moreover, the cream-SPI flavor improved the bread aroma by providing VOCs directly (acids, 2-nonanone, 2-undecanone, 2-tridecanone, and δ-dodecalactone) or precursor substances for VOC formation [esters, (E,E)-2,4-nonadienal, (E)-2-nonenal, and 1-octen-3-ol] during the bread-making process. The present study suggested that the partial substitution of SPI in cream after fermentation had great potential as a bread quality improver to enhance both the texture and aroma of bread.
Fifteen cheese protein hydrolysates were produced by using four different proteases. Then, the free amino acids (FAAs), molecular weight distribution (MWD), electronic tongue evaluation, and volatile compounds of the corresponding products were evaluated, respectively. The results suggested that 2SD had the strongest hydrolysis characteristic, followed by 6SD and FN. Samples hydrolyzed for less than 6 h or more than 18 h contained great defects of taste. Peptides with 150 Da–450 Da were mainly responsible for bitterness, saltiness, umami, and aftertaste in some enzyme hydrolysis. Under the same total enzyme concentration condition, the sample hydrolyzed by Flavourzyme and Neutrase for 18 h released more richness and less bitterness than the other systems, which were characterized by butter and cream odor. Notably, it was found for the first time that tetramethylpyrazine (TMP) was detected in cheese proteolysis with the highest content of 17.59 μg/g in Protease 2SD for 30 h. 2-Undecanone and acetoin played a key role in the flavor formation of the tested samples. Regarding the different chemical families of volatiles, acids were more abundant in the samples hydrolyzed by Protease 2SD and 6SD, while FN systems can achieve high ketone content.
The effect of spray-dried Soy–Cow's mixed milk enzyme modified (SC-EM) cheese on wheat dough properties and bread aroma was evaluated at either 0.1, 0.5, 1.0, 1.5 or 2.0% (w/w). Significant accumulation of amino acids and peptides of dough were noted as SC-EM cheese levels increased. After baking a total of 118 volatile compounds (VCs) were identified in breads having aldehydes, alcohols, esters and acids in major proportions. Higher contents of Maillard product 3-hydroxy-2-butanone, 2-methyl-1-propanol, phenylethyl alcohol, undecane, l-limonene, 2-pentyl furan and lipid oxidation compounds hexanoic acid ethyl ester, octanoic acid ethyl ester, decanoic acid ethyl ester, butanoic acid, hexanoic acid and octanoic acid were observed. Isoamyl alcohol, lactic acid ethyl ester, ethyl sorbate and sorbic acid were the newly identified VCs. These results revealed that SC-EM cheese could be used as improver in dough and contribution to bread aroma. Thus, SC-EM cheese has been proposed to be included in fortified bakery products.
Fermented dairy products are enjoying increased popularity as convenient, nutritious, stable, natural, and healthy foods. Lactic acid bacteria may contribute to the production of safer foods by inhibiting the growth of microbial pathogens and by removing chemical or toxic contaminants. Fermentation is one way to prolong the shelf life of meat and fish products and has been known since ancient times. The fermentation of vegetables, a practice that originated in the orient, has been used as a means of preserving food for more than 2000 years. Organic acids have been utilized for long time by the food industry as food additives and preservatives to prevent deterioration and extend the shelf life of perishable food ingredients. Microbial food and feed ingredients are composed of diverse ingredients composed of microorganisms or produced by fermentation. Bacteriocins are proteinaceous toxins produced by bacteria and archea members to inhibit the growth of similar or closely related bacterial strain(s).
Актуальность исследования и наличие пробелов в существующем знании на тему: Ферментно-модифицированный сыр (ФМС) широко применяют в молочной промышленности для производства ускоренно созревающего сыра, аналогов сыра и сырных продуктов, снековой продукции и др. При получении ФМС важно получить аромат соответствующего сыра. Аромат ФМС образуется целой группой веществ, включающих альдегиды, кетоны, летучие жирные кислоты, аминокислоты, лактаты и проч. На образование этих вкусоароматических компонентов влияют условия и глубина процесса ферментации. В данной работе проведена математическая оптимизация технологии получения ферментно-модифицированного сыра со сливочным ароматом. Планирование и анализ результатов эксперимента осуществляли с помощью системы статистического анализа – Statistica 10.0. В качестве плана эксперимента выбран трехуровневый полный факторный эксперимент, позволяющий оценить совместное влияние нескольких факторов при минимальном числе опытов. В качестве факторов, способных повлиять на качество сырного ароматизатора, выбраны дозировка ферментного препарата (0,2-1,0%), рН (4,5-6,5), температура (28-48 ºС) и продолжительность процесса ферментации (24-72 ч). Откликом служила органолептическая оценка получаемых в ходе эксперимента проб сырного ароматизатора, выраженная в баллах. Результаты и их обсуждение: В результате обработки экспериментальных данных получена математическая зависимость интенсивности запаха сырного ароматизатора (Y) от температуры (X1), рН среды (X2), продолжительности ферментации (X3) и дозировки фермента (X4). Получены графические интерпретации зависимости органолептической оценки от условий ферментации, профили предсказанных значений и функция желательности. С достаточной долей уверенности можно утверждать, что наиболее оптимальными параметрами процесса ферментации, позволяющими получить сырный ароматизатор наилучшего качества, являются следующие значения: температура ферментации – 48°С, рН – на уровне 4,5, продолжительность ферментации – 48 часов, дозировка фермента – 1 %.
Enzyme modified cheese production and applications continue to increase with the growth in convenience foods. Changes in labelling legislation continue to reduce the use of chemically derived or nature identical cheese flavors, which in turn has seen more developments in natural enzyme modified cheese production, which is seen as accelerated form of natural cheese production. The main production mechanisms involved in enzyme modified cheese have not changed significantly bu the use of different enzymes and substrates have seen a greater variety of cheese flavours becoming available. These trends are likely to continue as the potential range of cheese flavors that can be developed are effectively unlimited.
In mrture cheese, the developement of flavor and texture is largely controlled by intricate biochemical rerctions. In these reactions ,the proteins, lactose and fats inthe curd arc degraded principally by the rctivities of starter cultures and their enzymes. The dairy rcgearchcrs developed the enzyme modified cheese (EMC)'which are delined as concentrated cheose flavor produced enzymrticaly from cheese of various ages and are used as sn ingredient in processed food. An important objectlve of the present study was an rttempt to relatc the sensory properties of EMC to the level of key flavor active ingredients. Enzyme modified cheese are natural flavor ingredients manufsctured through the addition of a complement of proteolytic and lipolytic enzymes. In this study six different enzyme modified cheese slurry were prepared using trilo different cultures Lactococcus lactis subsp /aclis and Lactococcus lactls subps eremarls (R704) or Lactobacillus ca.rel (R82)' lipase, protssses or bovine pepsin and compared with control one. The results of these trials showed that the using of lipase with bovine pepsin is better than using lipare with protease, Also using culture R82 gave a better results than culture R704 depending on the chemical constituents and sensory point ofview.
The study was carried out on 9 yeast strains of Geotrichum candidum. The purpose of the study was to determine the ability of the yeast strains to produce extra- and intracellular lipases in shake cultures in a medium containing 2% and 3% of rapeseed oil used as a carbon source, after deep frying of Frenchfries. Biosynthesis of these enzymes in an AK-210 bioreactor at a working volume of 5 L was analyzed. Lipase activity was determined using olive oil (JLO) and glycerol tributyrate (JLT) as substrates. The results obtained in shake cultures showed that the best carbon source was the medium containing 2% of olive oil, while the best producer of extracellular lipases (198 JLZO mL-1) was the strain of G. candidum MSK3-11. Lipase synthesis in the bioreactor was begun at the exponential phase of growth. The activity of extracellular lipases amounted to 88 JLZO mL-1 at biomass yield of 14 g L-1 at a stationary phase. Irrespective of the strain and the medium, both extra- and intracellular activity was higher with the use of olive oil than with tributyrin.
Dairy-derived aromas and flavors are widely used in the food industry. Nowadays, the traditional milk-derived products, such as cheese and butter, are more and more replaced by novel ingredients that are obtained by fermentation or enzymic modification. These ingredients offer more intense flavors and lower costs. In the past, the emphasis has been on the development of enzymes, production strains and substrates for flavor and aroma production. Downstream processing was usually limited to concentration of the fermented liquid, optionally followed by drying. New developments in distillation and membrane technology offer new opportunities for the production of highly concentrated dairy-derived flavors and aromas.
This review highlights opportunities to deliver new flavour technologies based on the ripening processes that occur in natural cheese. The process control and product consistency that has been achieved during industrial scale-up of the cheesemaking process can now be used as a platform on which to introduce consumer-targeted attributes in flavour and functionality. Also, the conversion of the milk carbohydrates, milk proteins and milkfat substrates to produce the complex of flavour compounds that together make up cheese flavour can now be separated from the cheesemaking process and amplified or moved in a specific direction to develop customer-targeted flavour. While enzyme modified cheese is a mature example of such technology, combining hydrolytic enzymes with culture technology has allowed the development of flavour products that can be used to produce specific flavour profiles. The development of a smear-brick flavour concentrate is described as an example. The review also describes how understanding the structure and function of the esterase enzymes of lactic acid bacteria may enable us to redirect enzyme and culture activity to achieve new flavour end points, both in natural cheese and dairy flavour fermentations. The opportunities to exploit these new flavour technologies in cheese and new food formats is discussed.
Biotechnology which is synonymous with genetic engineering or recombinant DNA (rDNA) is an industrial process that uses the scientific research on DNA for practical applications. rDNA is a form of artificial DNA that is made through the combination or insertion of one or more DNA strands, therefore combining DNA sequences, within different species, that is, DNA sequences that would not normally occur together. To understand the significance and the various applications of biotechnology, a basic knowledge of rDNA technology is indispensable. This chapter outlines the gene cloning techniques and explanations of gene expression and plasmid stability. The polymerase chain reaction (PCR) technique, which is based on the enzymatic amplification of a DNA fragment from oligonucleotide primers, is useful not only for amplifying target sequences but also for altering a particular nucleotide sequence.
Food biotechnology is the application of modern biotechnological techniques to the manufacture and processing of food, for example through fermentation of food (which is the oldest biotechnological process) and food additives, as well as plant and animal cell cultures. New developments in fermentation and enzyme technological processes, molecular thermodynamics, genetic engineering, protein engineering, metabolic engineering, bioengineering, and processes involving monoclonal antibodies, nanobiotechnology and quorum sensing have introduced exciting new dimensions to food biotechnology, a burgeoning field that transcends many scientific disciplines. Fundamentals of Food Biotechnology, 2nd edition is based on the author's 25 years of experience teaching on a food biotechnology course at McGill University in Canada. The book will appeal to professional food scientists as well as graduate and advanced undergraduate students by addressing the latest exciting food biotechnology research in areas such as genetically modified foods (GMOs), bioenergy, bioplastics, functional foods/nutraceuticals, nanobiotechnology, quorum sensing and quenching. In addition, cloning techniques for bacterial and yeast enzymes are included in a "New Trends and Tools" section and selected references, questions and answers appear at the end of each chapter. This new edition has been comprehensively rewritten and restructured to reflect the new technologies, products and trends that have emerged since the original book. Many new aspects highlight the short and longer term commercial potential of food biotechnology.
A novel method to produce cheese flavor powder by combination mold fermentation and enzyme acceleration was developed. In this research, Actinomucor elegans was selected to ferment the milk. The optimum conditions for fermentation were 220 rpm, at the temperature 29C and for 2 days. In order to accelerate the flavor formation, the effects of lipase and protease to fermented milk were also investigated. According to the sensory evaluation scores, as well as the degree of hydrolysis, the optimum formula of enzymes were Palatase 2000 L 2‰ (m/v) and proteases 1‰ (m/v), proteases was prepared by mixing 2:1 (m/m) proportion of Flavourzyme 500MG and Neutrase 1.5MG. The optimum conditions for enzymolysis were 50C, 6.5 (initial pH) and 6 h (enzymolysis time), and the product of optimum process was tested by gas chromatography–mass spectrometry (GC-MS). According to the sensory evaluation result and GC-MS, the novel cheese flavor powder showed superior profile for its intensity and flavorful.
Cheese production has been considered as an important raw material of some food because of its great aroma and flavor. The novel cheese flavor powder is a product retaining the strong aroma and flavor of cheese, namely, creamy, odor, sour and pungent. The cheese flavor powder is mainly used as a spice in culinary preparations for imparting a characteristic cheese flavor. The product is generally light yellow in color and is stable in quality because of mealy structure and low moisture content. It is a ready-to-use preparation, which can be used in homes, restaurants and institutional catering. The development of novel cheese flavor powder with richer flavor, lighter weight and ease of use may be governed by a mass of customer favorite.
An accurate, reproducible and generally applicable procedure for determining the degree of hydrolysis of food protein hydrolysates has been developed. The protein hydrolysate is dissolved/dispersed in hot 1% sodium dodecyl sulfate to a concentration of 0.25-2.5 × 10-3 amino equivalents/L. A sample solution (0.250 mL) is mixed with 2.00 mL of 0.2125 M sodium phosphate buffer (pH 8.2) and 2.00 mL of 0.10% trinitrobenzenesulfonic acid, followed by incubation in the dark for 60 min at 50 °C. The reaction is quenched by adding 4.00 mL of 0.100 N HCl, and the absorbance is read at 340 nm. A 1.500 mM L-leucine solution is used as the standard. Transformation of the measured leucine amino equivalents to degree of hydrolysis is carried out by means of a standard curve for each particular protein substrate.
The concentrations of L- and D-lactic acid and free fatty acids, C4:0 to C18:3, were quantified in a range of commercial enzyme-modified Cheddar cheeses. Lactic acid in Cheddar enzyme-modified cheeses varied markedly depending on the manufacturer. Differences in the ratio of L- to D-lactic acid indicate that cheeses of different age were used in their manufacture or contained varying levels of nonstarter lactic acid bacteria. The level of lipolysis in enzyme-modified cheese was higher than in natural Cheddar cheese; butyrate was the predominant free fatty acid. The addition of exogenous acetate, lactate, and butyrate was also indicated in some enzyme-modified cheeses and may be used to confer a specific flavor characteristic or reduce the pH of the product. Propionate was also found in some enzyme-modified cheese products and most likely originated from Swiss-type cheese used in their manufacture. Propionate is not normally associated with natural Cheddar cheese flavor; however, it may be important in the flavor and aroma of Cheddar enzyme-modified cheese. Levels of lipolysis and glycolysis appear to highly controlled as interbatch variability was generally low. Overall, the production of enzyme-modified Cheddar cheese involves manipulation of the end-products of glycolysis (lactate, propionate, and acetate) and lipolysis to generate products for specific applications.
Carbohydrate Chemistry provides review coverage of all publications relevant to the chemistry of monosaccharides and oligosaccharides in a given year. The amount of research in this field appearing in the organic chemical literature is increasing because of the enhanced importance of the subject, especially in areas of medicinal chemistry and biology. In no part of the field is this more apparent than in the synthesis of oligosaccharides required by scientists working in glycobiology. Clycomedicinal chemistry and its reliance on carbohydrate synthesis is now very well established, for example, by the preparation of specific carbohydrate- based antigens, especially cancer-specific oligosaccharides and glycoconjugates. Coverage of topics such as nucleosides, amino-sugars, alditols and cyclitols also covers much research of relevance to biological and medicinal chemistry. Each volume of the series brings together references to all published work in given areas of the subject and serves as a comprehensive database for the active research chemist Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading authorities in the relevant subject areas, the series creates a unique service for the active research chemist, with regular, in-depth accounts of progress in particular fields of chemistry. Subject coverage within different volumes of a given title is similar and publication is on an annual or biennial basis.
This article is a revision of the previous edition article by M. G. Wilkinson and K. N. Kilcawley, Volume 1, pp 434–438, © 2002, Elsevier Ltd.
This review highlights areas of interest in the production of enzyme-modified cheese. The demand for cheese flavours has increased due to consumer demand for a wider choice of convenience and low-fat products that possess cheese flavour. At present the best method for producing economic and consistent cheese flavours is through enzyme-modified cheese production. Essentially, the technology used to produce enzyme-modified cheese involves incubating cheese/curd with enzymes (proteinases, peptidases, lipases and esterases) in a slurry system under controlled conditions until the required flavour is reached. The flavour profile of enzyme modified cheese can be up to 30 times the intensity of natural cheese. A myriad of cheese flavours can be produced in this manner but a detailed understanding of the biochemistry of cheese flavours is required before production can be achieved on a consistent basis.
Crude fractionation of cheese by various precipitants and subsequent determination of soluble nitrogen (N) represents a well-established method for quantification of proteolysis in cheese. Attempts have been made to replace precipitation with 12% trichloracetic acid (TCA) by fractionation with differing concentrations of ethanol (EtOH). In order to compare these procedures, aqueous extracts of Emmental cheeses were fractionated with EtOH at concentrations ranging from 30 to 70%. N recovery increased significantly with increasing cheese age and, for each cheese, decreased with increasing EtOH concentration. For young cheese, precipitation with 30–40% EtOH gave comparable results to fractionation with 12% TCA. For mature cheese, however, 70% EtOH was necessary to achieve N values corresponding to precipitation with 12% TCA. Analytical ultrafiltration of aqueous cheese extracts and N recovery in fractions thereof prepared by TCA and EtOH, as well as SDS-PAGE and RP-HPLC of the EtOH-soluble and EtOH-insoluble fractions, showed that variations in cut-off levels can be attributed to qualitative differences in extract composition.
Enzyme-modified cheese is derived from cheese by enzymatic means. Enzymes may be added during the manufacture of cheese or after aging. An incubation period under controlled conditions is required for proper flavor development. The mechanism of flavor development in enzyme-modified cheese may be related to the curing of cheese. Although many of the mechanisms for flavor development in cheese are not well understood, carbohydrates, proteins, and fat undergo enzymatic degradation during cheese aging, and these reactions are important in the development of flavor in cheese and enzyme-modified cheese. In some instances, the flavor profile or intensity is proportional to the degree of lipolysis and release of low molecular weight free fatty acids as with Romano or Provolone cheese. In other cases, a similar free fatty acid profile enhances both Cheddar flavor and Swiss cheese flavor but is not characteristic for either.Enzyme-modified cheeses are generally added to foods at levels of .1 to 2.0%, although they can be used at 5% of the formulation to add dairy or cheesy notes to foods and to reduce the requirement for aged cheese in food formulations.
Lactobacilli commonly occur in natural cheese because they are used as a starter culture (e.g., Swiss cheese) or enter milk and, thus, cheese as postpasteurization (or heat treatment) contaminants (e.g., Cheddar cheese). Cell-wall-bound, intracellular, and extracellular proteinases occur in lactobacilli; those from some species of Lactobacillus preferentially hydrolyze αs1-casein, whereas those from others prefer β-casein. Peptides released from casein by proteinases are subsequently hydrolyzed by peptidases inside cells of lactobacilli. The intracellular peptidases are a vital part of the mechanism by which lactobacilli make free amino acids that are precursors of some cheese flavor compounds. Aminopeptidase, dipeptidase, carboxypeptidase, and endopeptidase activities have been associated with lactobacilli. Although largely intracellular, membrane-associated peptidases have been noted. Intracellular lipases and esterases also occur in lactobacilli, but activity of these enzymes has been designated as “weak”. Despite this, they probably contribute to flavor development in some varieties of cheese. Certain lactobacilli can cause defects such as formation of white crystals of calcium lactate on the surface of cheese or of biologically active amines that sometimes can cause illness in consumers.
The compositional and proteolytic parameters in a range of commercial enzyme-modified Cheddar cheeses were quantified, with large variations evident between products from the same manufacturer and from different manufacturers. Analysis of the products indicated the use of cheese of varying fat content, exogenous protein and/or fat, emulsifying salts, flavour potentiators and bulking agents. Extensive proteolysis was a characteristic of these commercial products. Overall, production of enzyme-modified Cheddar cheese involves manipulation of both composition and proteolysis to generate products for specific applications.
The enzyme complement of a selection of commercial food-grade peptidase and lipase preparations was investigated. Each preparation was assayed for protein content, proteinase activity at pH 5.5 and 7.0 at 37°C using azocasein and semi-quantitatively assayed for lipase, peptidase, proteinase, phosphatase and glycosidase activity by the API-ZYM system. Each peptidase preparation was also assayed for various endo-, carboxy-, amino- and di-peptidase activities at pH 5.5 and 7.0 at 37°C, using chromogenic or fluorogenic substrates, while each lipase preparation was assayed for esterase and lipase activity at pH 7.0 at 37°C using p-nitrophenol substrates. All enzyme preparations were found to contain enzyme activities in addition to their stated main activity. According to the API-ZYM system the peptidase preparations contained varying levels of lipase, proteinase, peptidase, phosphatase and glycosidase activity, with the lipase preparations containing lipase, phosphatase and glycosidase activity. Only two peptidase and two lipase preparations contained significant amounts of proteinase activity as measured by azocasein. The peptidase and lipase activities of the preparations appeared to be dependent upon source. Most peptidase preparations had significantly more activity at pH 7.0 than at 5.5.
Twenty three commercial microbial proteinase preparations derived from various Bacillus or Aspergillus spp. or from Rhizomucor niveus were assessed for proteolytic activity on azocasein at pH 5.5 or 7.0, or specificity on sodium caseinate at pH 5.5 and semi-quantitatively assessed for esterase, lipase, trypsin, chymotrypsin, general aminopeptidase, phosphatase and glycosidase activities using the API-ZYM system. Selected preparations were further assayed for peptidase, esterase and lipase activities at pH 7.0. The proteolytic activity of the Bacillus preparations was greater at pH 7.0, while that of the Aspergillus and Rhizomucor preparations was greater at pH 5.5. All the Bacillus preparations contained one of two main proteolytic activities, thought to be either bacillolysin or subtilisin. Most of the Aspergillus preparations contained the same proteinase, thought to be aspergillopepsin I, but two preparations appeared to contain a different unidentified proteinase. The proteolytic specificity of the Rhizomucor preparation was different from the Bacillus or Aspergillus preparations; thought to be rhizopuspepsin. According to the results of the API-ZYM system, all preparations contained enzyme activities in addition to their main proteolytic activity, with the Aspergillus and Rhizomucor preparations containing the highest levels and widest range of activities. Generally preparations derived from Aspergillus contained the highest level of general, proline and endopeptidase activities, with the Bacillus preparations conspicuous by the absence of general and proline-specific peptidase activities, while the Rhizomucor niveus preparation contained little or no general or endopeptidase activity. Esterase activity was found in all of the preparations evaluated, with only two Aspergillus preparations containing lipase activity.
The addition of live and heat-shocked Lactobacillus casei-casei L2A and Neutrase© was tested for its ability to accelerate the maturation of Cheddar cheese. An evaluation of physicochemical and rheological properties showed that cheese pH was decreased by bacterial and enzymatic additives, while fracturability and cohesiveness were influenced principally by Neutrase. The integrated process recommended is composed of three parts: first, the addition of live L. casei-casei L2A to control the undesirable microflora, second, heat-shocked cells of the same species at a concentration of 1.0%, and third, Neutrase at a concentration not higher than 1.0 × 10-5 AU/g of cheese. This process led to a good-quality sharp Cheddar cheese with 60% increase in flavor intensity compared to control cheese.
A rapid, reliable and precise capillary gas chromatographic method for routine quantification of short- and long-chain free fatty acids (FFA) in milk and cheese is described. Procedures of (1) lipid extraction, (2) isolation of the FFA from milk and cheese extracts, and (3) capillary gas chromatographic analysis were developed and optimized. FFA can be extracted from cheese for 95–100% with ether-heptane after grinding with sodium sulfate and addition of 2.5 M sulfuric acid. From milk, 95–100 % of the FFA (≤ C8:0) are also extracted with ether-heptane after addition of ethanol and 2.5 M sulfuric acid. Internal standards are used to compensate for the losses of lower FFA (C2:0–C8:0) in the aqueous phase. In view of the excellent recovery (98–100 %) and a considerable saving of time, the use of an aminopropyl column is preferred for the isolation of the FFA from lipid-extracts. The underivatized FFA are separated directly by capillary gas chromatography making use of columns which enable accurate and rapid (≤ 40 min) determination of FFA C2:0–C20:0. With the method described, all major FFA (C2:0–C18:3) in milk and cheese can be quantified with good repeatability (rsd less then 2 %). The method is also applicable to the analysis of short-chain fatty acids in other products.
The problem of balancing out the effect of order of presentation and the carryover effect of a preceding sample over a series of presentations of the same set of samples is addressed. A series of designs developed by Williams (1949) are used. The method of calculation is given. Tables containing about 50 consumers of each design for presenting from 4 through to 16 samples are given.
The odor and flavor characteristics of 15 commercial Cheddar-flavored enzyme-modified cheeses (EMC) and 3 natural Cheddar cheeses were determined and compared using descriptive sensory analysis. These sensory characteristics of Cheddar EMC were significantly different from those defined for natural Cheddar cheeses. EMC provided a range of “vomit,”“bitter,”“astringent,”“chemical,” and “eggy/sulphur” flavors, whereas the natural Cheddar cheeses were characterized by “sweet,”“caramel,”“creamy,”“nutty,” and “buttery” flavors. Relationships between the composition of EMC and their sensory attributes showed significant correlation. The flavor attributes “pungent,”“vomit,”“astringent,” and “eggy/sulphur” were strongly related to a high fat content and low pH. These relationships were discussed and compared to those observed for natural Cheddar cheeses.
The aroma, flavour and texture of 16 samples of commercial Cheddar cheese have been profiled after ripening at 10 °C for 3, 4, 6, 8, 10 and 12 months. Systematic changes in sensory character have been studied and the main changes during maturation identified. Although sensory character changed slowly during ripening, assessment early in the maturation period was an unreliable estimate of ultimate sensory character. Progressive changes in Cheddar aroma and flavour, creamy flavour, acid flavour and mouth-coating character were noted during ripening. Changes in minor components of aroma and flavour were also observed but, on average, were small. Two samples eventually developed marked rancid character and another became excessively bitter. The relation between gross composition of the cheese and sensory properties was investigated. In the early stages of ripening, the ratings for Cheddar flavour and mouth-coating character were associated with the salt content of the cheese and with the concentration of fat in dry matter. However, as the cheese matured these associations weakened.
Though designed by nature to effect hydrolysis of lipids, lipases can, under appropriate reaction conditions, promote ester formation through reaction of acids and alcohols (esterification) or of esters with acids (acidolysis), alcohols (alcoholysis), or other esters (interesterification). Compared with chemical processes already carried out on an industrial scale enzymic reactions occur under milder (and ‘greener’) conditions though they may take longer. Of greater significance is the specificity shown by the enzymes which permits the formation of lipid derivatives not easily prepared by conventional laboratory procedures.This review describes the lipases and their various specificities and reports on their use in hydrolysis and in the production of phospholipids, fatty acids, alkyl esters, mono- and di-acylglycerols, triacylglycerols, other esters, and amides. Some of these have already led to marketable products but for the most part the full potential of these reactions has yet to be realised. The reactions of other enzymes promoting interesting reactions at unsaturated centres are also described.© 1999 Society of Chemical Industry
Enterococci are gram-positive bacteria and fit within the general definition of lactic acid bacteria. Modern classification techniques resulted in the transfer of some members of the genus Streptococcus, notably some of the Lancefield’s group D streptococci, to the new genus Enterococcus. Enterococci can be used as indicators of faecal contamination. They have been implicated in outbreaks of foodborne illness, and they have been ascribed a beneficial or detrimental role in foods. In processed meats, enterococci may survive heat processing and cause spoilage, though in certain cheeses the growth of enterococci contributes to ripening and development of product flavour. Some enterococci of food origin produce bacteriocins that exert anti-Listeria activity. Enterococci are used as probiotics to improve the microbial balance of the intestine, or as a treatment for gastroenteritis in humans and animals. On the other hand, enterococci have become recognised as serious nosocomial pathogens causing bacteraemia, endocarditis, urinary tract and other infections. This is in part explained by the resistance of some of these bacteria to most antibiotics that are currently in use. Resistance is acquired by gene transfer systems, such as conjugative or nonconjugative plasmids or transposons. Virulence of enterococci is not well understood but adhesins, haemolysin, hyaluronidase, aggregation substance and gelatinase are putative virulence factors. It appears that foods could be a source of vancomycin-resistant enterococci. This review addresses the issue of the health risk of foods containing enterococci.
The rapid release of intracellular enzymes due to autolysis of lactic acid bacteria in the cheese matrix post-manufacture is thought to play a role in the acceleration of cheese ripening. To investigate this hypothesis Cheddar cheese was manufactured using three related starter systems which varied with respect to their autolytic properties. Starter system A contained a blend of two Lactococcus lactis strains (223 and 227) which had a low level of autolysis. System B was identical to A but included an adjunct of a highly autolytic strain of Lactobacillus helveticus (DPC4571). System C consisted only of strain DPC4571 as starter. The cheeses were evaluated during ripening for key ripening indices including autolysis of starter cells by release of intracellular marker enzyme lactate dehydrogenase (LDH), composition, proteolysis and flavour development by descriptive sensory analysis. Populations of Lb. helveticus DPC4571 decreased rapidly in cheeses B and C and were not detected by 8 weeks. The level of starter culture autolysis proceeded in the order C≫B>A. Levels of proteolysis were elevated in cheeses B and C relative to A. Principal component analysis of the sensory data separated the character of cheese A from that of cheeses B and C. Cheeses B and C developed a unique ‘balanced’ ‘strong’ flavour early in ripening with a ‘caramel’ and ‘musty’ odour and ‘sweet’ ‘astringent’ flavour compared to cheese A. Hierarchical cluster analysis grouped C at 2 months with B at 6 and 8 months reflecting accelerated flavour development. Proteolytic and sensory data support the hypothesis that autolysis accelerates the rate of cheese ripening.
The effects of crude enzyme extract of Lactobacillus casei ssp. casei LLG on the water-soluble peptides of enzyme-modified cheese (EMC) were studied by reverse phase HPLC and amino acid analysis. A wide range of peptidolytic activities (aminopeptidase 1615.44 unit/ml; x-prolyldipeptidyl peptidase 66–73 unit/ml; proline-iminopeptidase 38–63 unit/ml) were detected in the crude enzyme extract. Bitter enzyme-modified cheese (EMC N24) was prepared with Neutrase® 0.-5L for 24 h at 45 °C and treated with (EMC NL72) and without (EMC N96) the crude enzyme for 72 h at 35 °C. The percent peak areas of two hydrophobic peptides (peak I and peak II) in EMC N24 were increased from 1.63% to 3.65% and from 0.88% to 3.23% in EMC N96, respectively, but decreased to below the detectable range in EMC NL72. The bitterness of EMC N96 may have been related to the increase in areas of these two peaks. Based on the amino acid compositions, peak I was identified as the αsl-casein fraction 26–31(Ala-Pro-Phe-Pro-Glu-Val), and peak II as the β-casein fraction 190–192 (Phe-Leu-Leu), respectively. The results suggest that both aminopeptidase and proline-specific peptidases present in the crude extracts are responsible for degrading the hydrophobic peptides in bitter EMC.
Glutaminase is widely distributed in microorganisms including bacteria, yeast and fungi. The enzyme mainly catalyzes the hydrolysis of γ-amido bond of l-glutamine. In addition, some enzymes also catalyze γ-glutamyl transfer reaction. A highly savory amino acid, l-glutamic acid and a taste-enhancing amino acid of infused green tea, theanine can be synthesized by employing hydrolytic or transfer reaction catalyzed by glutaminase. Therefore, glutaminase is one of the most important flavor-enhancing enzymes in food industries. In this review, subsequent to a discussion on the definition of glutaminase, the enzymatic properties, applications of glutaminase in the food industry, and occurrence and distribution of the enzyme are described. We then illustrate the gene cloning, primary structure, and 3D-structure of glutaminase. Finally, to facilitate the future applications of glutaminase in food fermentations, the mechanisms of action of salt-tolerant glutaminase are briefly discussed.
The principal pathways for the formation of flavour compounds in cheese (glycolysis, lipolysis and proteolysis) are reviewed. Depending on variety, microflora and ripening conditions, lactate may be metabolized by a number of pathways to various compounds which contribute to cheese flavour or off-flavours. Citrate metabolism by citrate-positive lactococci or Leuconostoc spp. is important in certain varieties (e.g., Dutch cheeses). Lipolysis results directly in the formation of flavour compounds by liberating free fatty acids (FFA). FFA may also be metabolized to alkan-2-ones and fatty acid lactones. Proteolysis of the caseins to a range of small-and intermediate-sized peptides and free amino acids (FAA) probably only contributes to the background flavour of most cheese varieties, but FAA are important precursors for a range of poorly-understood catabolic reactions which produce volatile compounds essential for flavour.
An aminopeptidase of broad specificity was extracted by cell lysis of a selected strain of Lactobacillus casei subsp. rhamnosus during the late exponential phase. The enzyme was purified 195-fold from crude extract by using an f.p.l.c. system. Native and SDS/PAGE of the purified enzyme showed a single protein band of 89 kDa. The maximum aminopeptidase activity was observed at pH 7.0 and 39 degrees C. The enzyme hydrolysed a range of nitroanilide-substituted amino acids, as well as dipeptides, and accounted for most of the aminopeptidase activity found in cell-free extracts. The enzyme activity was inhibited by metal chelators such as EDTA and 1,10-phenanthroline. Cobalt ions only stimulated aminopeptidase activity and were also able to re-activate the enzyme previously inhibited by metal chelators. The Km and Vmax. values of the aminopeptidase for leucine p-nitroanilide were 0.06 mM and 12.6 mmol/min per mg of protein respectively. This enzyme was stable over the pH range of 5-9 and below 45 degrees C.
Ten batches of Cebreiro, a fresh or short-ripened acid-curd cheese, produced in the Galician mountains (NW Spain) were prepared from pasteurized milk inoculated with microorganisms isolated from raw-milk cheese. Two control batches were made with a Lactococcus lactis subsp. lactis starter; 8 batches were made with the lactococcal starter plus one of eight Enterococcus faecalis cultures: 4 E. faecalis var. liquefaciens (EFLB) and 4 E. faecalis var. faecalis (EFFB). Whey dry matter in the EFLB was notably higher than in the control batches and this was related to lower cheese yields. After over 15 days storage the highest counts of both aerobic bacteria and lactic acid bacteria were observed for the EFLB. The lower content in protein on dry matter was found in the EFLB. The beta-casein broke down to a greater extent in the EFLB than in the EFFB, the lowest values being obtained for the control batches. The higher level of hydrolysis of alphax1-casein and maximum peptide alpha(s1) - I/alpha(s1)-casein ratio were obtained for EFFB at day 15 of storage. In all the batches made with enterococci soluble nitrogen was higher than in the control batches, with the highest values in the EFLB. In all the batches made with enterococci, volatile free fatty acid, long-chain free fatty acids and diacetyl and acetoin contents at days 10 and 15 of storage were higher than in the control batches, the highest values being obtained for EFLB. Acetic acid in all batches accounted for the main proportion of the volatile free fatty acids. Butyric and caproic acids were not detected in the volatile free fatty acids fractions of the control batches, but both acids were detected in most of the batches made with enterococci. The more intense acid taste was found in the EFFB and control batches, the most bitter taste being found in the EFLB. Buttery, rancid and spicy flavors were more evident in the EFLB. The rancid and spicy flavors were positively correlated with the contents of volatile free fatty acids and long-chain free fatty acids. The cheeses of EFLB proved to be more crumbly than the EFFB, whereas the stickiness and deformability were higher in the EFFB. The batches with similar organoleptic characteristics to those of traditional cheese were the batch IV made with the less proteolytic strain of E. faecalis var. liquefaciens, and the batch VI made with a moderate lipolytic activity strain of E. faecalis var. faecalis.
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Attribute difference tests: simple ranking test
- Meilgaard
Chemical and physical methods
- Case