Food Technology
Mohammad Hadian; Mostafa Mazaheri Tehrani; Mohsen Ghods rohani
Abstract
IntroductionDoogh is a fermented dairy product that is produced by blending yogurt with water and some salt. This fermented beverage is widely consumed as a refreshing drink in Iran and other Middle East countries. Doogh is a source of calcium needed by the body on a daily basis and contains B vitamins ...
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IntroductionDoogh is a fermented dairy product that is produced by blending yogurt with water and some salt. This fermented beverage is widely consumed as a refreshing drink in Iran and other Middle East countries. Doogh is a source of calcium needed by the body on a daily basis and contains B vitamins that are effective in the health and strength of teeth and bones. In addition, doogh contains a low percentage of fat, which makes it a diet drink. Whey Protein Concentrate (WPC) is a product contains 25 to 89% protein and different amounts of lactose, fat and minerals. Due to the functional properties of whey protein and its nutritional value; whey protein is widely used in dairy products. The development of cross-linking bonds between protein chains by enzymes is very important today. Enzyme cross-linking of proteins can affect some of their functional properties such as solubility, water absorption, rheological and emulsifying properties. One of the most widely used enzymes in the food industry is the transglutaminase enzyme. In this study the effects of WPC in three levels (0%,1% and 2%) and the transglutaminase enzyme in two levels (0 and 1 unit per gram of milk protein) in two method of dough preparation (adding water to yogurt and fermented milk diluted with water) on rheological characteristics, and microstructure of doogh were studied. Material and MethodsRaw milk was provided by Pegah Khorasan Company, WPC from Multi Company) Mashhad (and Trans glutaminease enzyme from BDF Company of Spain. WPC was first added to milk at 45 ̊ C at three levels of zero, 1 and 2%.The milk samples were then pasteurized at 85 ̊ C for 30 min. After lowering the temperature to 45 ̊ C, the enzymatic operation was performed at two levels of zero and one unit (per gram of protein).To complete the enzyme function, the samples were incubated for 180 minutes at 45 ̊ C. Then a temperature of 90 ̊ C was applied for 1 minute to inactivate the enzyme. The samples were then cooled to 45 ̊ C. At this stage, the samples were divided into two parts. In one part of the samples; milk was diluted with water in a ratio of 6% of the total dry matter for direct production of doogh. After adding the starter, the samples were transferred to an incubator and hold at 43-42 ̊ C, until the pH reaches about 4.1.Thefermented samples were then transferred to a refrigerator. In the second part, starter was added to milk to produce yogurt; after adding starter, the mix was transferred to an incubator and hold at 43-42 ̊ C, until the pH reaches about 4.1. Doogh was produced by diluting yogurt with waterto givethe final product with 6% of total dry matter. Results and Discussion In both production methods, in samples treated only with WPC, the average particle size increased with increasing WPClevel. In both methods, the production of only enzymatically treated samples led to the formation of smaller particles with a more uniform shape and distribution. In samples of doogh produced by both production methods, WPC and transglutaminase enzyme changed the flow characteristics of doogh to non-Newtonian behavior. Samples made directly from milk had significantly higher viscosity than samples made from yogurt. In samples without enzymatic treatment, the microstructure was smooth and homogeneous with smaller particles than other samples. These particles settle very quickly. In the samples where WPC treatment was applied, the amount of large particles and non-uniformity increase with increasing WPC level. The distribution of particles in samples made directly from milk was more regular than samples made from yogurt.
Seyed Ali Mohammadi; Mohsen Ghods rohani; Masoud Najaf Najafi; Morteza Kashaninejad
Abstract
Introduction: In recent years, with increasing public awareness about the harmful effect of fat consumption, demand for low-fat dairy products has increased significantly. On the other hand, fat reduction reduces the rheological and sensory properties of food, such as taste, flavor, texture and mouth ...
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Introduction: In recent years, with increasing public awareness about the harmful effect of fat consumption, demand for low-fat dairy products has increased significantly. On the other hand, fat reduction reduces the rheological and sensory properties of food, such as taste, flavor, texture and mouth feel. Therefore, it is difficult to produce a low-fat product with the same characteristics of high-fat product. In order to imitate different functions of fat in low-fat foods, such as consistency of the product, mouth feel, color, flavor and rheological properties should be considered. Fat substitutes are macromolecules that are used to provide all or part of the fat functions in a food product and produce less calorie intake than fat. Konjac is a neutral and polysaccharide hydrocolloid that is used as a gelling agent in traditional Asian foods due to its high ability in absorbing water. In addition, it is one of the most viscous dietary fiber. The use of konjac in western countries is expanding as a component in functional foods. Konjac can therefore be used as an appropriate substitute for fat in dairy products such as cream, which in addition to reducing the amount of fat can maintain and even improve the physical and other properties of the product. The purpose of this study was to produce low-fat cream with good nutritional value, variety in formulation, as well as lower prices. Materials and methods: Fresh cream of 30% fat and pasteurized milk were purchased from Razavi Dairy Company and konjac gum was provided from Food Chem (China). First, the gum was mixed with the pasteurized milk at 45°C. Then the mixture was added to the cream of 30% fat to reach the fat content of 18– 25%. The final mixture, after homogenization in the different specified values of pressure, was pasteurized at 85°c for 15 min, and then packed in polyethylene bottles and kept in the refrigerator (4ºC) until theday of experiment. The effect of amounts of Kanjac gum (0.2- 0.6), the amount of fat (18- 25%) and homogenization pressure (100- 200 bar) on the sensory, color, and rheological characteristics of low-fat cream were investigated Results and discussions: The results of evaluating the characteristics measured using the response surface methodology indicated that the hardness, consistency, adhesiveness, b*, sensory score of texture, sensory score of aroma and overall acceptance of samples significantly increased with an increasing homogenization pressure. Also increasing fat content caused an increasing the adhesiveness, L*, b*, sensory score of taste, sensory score of aroma and total acceptance of samples. Increasing the konjac gum content also increased hardness, consistency, adhesiveness, and sensory score of texture. The distribution of responses in the principal component also showed that the instrumental measures like hardness and consistency were close to the sensory score of texture of the samples. This proximity of these attributes indicated that the properties measured by the panelists were approximately equivalent to the parameters which were measured by instrumental methods. Also, the results of the correlation coefficient between sensory and instrumental measurements showed that the highest correlation between hardness and sensory score of texture (a strong positive linear relationship (0.774), and between the consistency and sensory score of texture (a strong positive linear relationship (0.760)). Rheological and sensory properties in products such as cream, play an important role in the processing and marketability of the product. In cream, these characteristics are mainly influenced by the method of production, the amount of fat, and potential additives used. The results of this study showed that konjac gum as a hydrocolloid can be used as a proper substitute for fat in the cream, and with suitable sensory, color and rheological properties. The results of this study about the correlation between sensory properties and instrumental specification showed that the properties measured by the panelists are approximately equivalent to the parameters measured by the instrumental methods. Therefore, the results of instrumental methods in most cases can well predict the sensory properties of the cream and then can be replaced it.
Mostafa Kashaninejad; Masoud Najaf Najafi; Mohsen Ghods rohani; Morteza Kashaninejad
Abstract
Introduction: Labane or concentrated yoghurt is a semi-solid product which is being producedd by dehydration of yoghurt or separation of water and some water-soluble solids from yoghurt. High nutritional value, long shelf life, more desirable taste and texture and feasibility to produce other product ...
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Introduction: Labane or concentrated yoghurt is a semi-solid product which is being producedd by dehydration of yoghurt or separation of water and some water-soluble solids from yoghurt. High nutritional value, long shelf life, more desirable taste and texture and feasibility to produce other product are the reasons for high acceptance among customers. There are wide ranges of production methods from traditional methods which are tedious, such as separation of whey by fabric bags, to complicated time-consuming methods which also contaminate product and reduce its nutritional value. These cause demand to establish more suitable methods such as “wheyless process” by dried milk, concentrated milk protein or concentrated whey protein. On the other hand, one of the methods for enhancing firmness and textural properties of yoghurts, similar to other dairy products is utilization of hydrocolloids. These components are used for enhancing rheological an textural properties of food and commonly used as additives for increasing viscosity, gel forming ability, enhancing physical stability, film forming ability, controlling crystallization, postponing syneresis and textural improvement. Konjac gum (KG) is a neutral polysaccharide that derived from Amorphophallus konjac C. Koch tuber, which is well known in east countries during centuries. Ability to hold water and reduction of cholesterol and glucose are the reasons for grossing demand of this gum. So due to the importance of labane produced through wheyless process, the effect of different ingredients of formulation such as milk protein concentrate, cheese whey powder and konjac gum on physicochemical, rheological and sensory properties of labane was investigated and compared these properties by using Principal component analysis (PCA) and Partial least squares regression (PLS regression). Materials and methods: Cow milk was purchased from local market (Mashhad, Iran). Dried skim milk, milk protein concentrate, cheese whey powder and commercial starter provided from Khorasan Razavi Pegah Company (ABY1, Christian Hansen, Horsholm, Denmark) and KG purchased from Food Chem. (China). In order to concentrate the milk, 3% dried skim milk was added to1 Kg milk. Then, according to the experimental design (table 2), MPC and CWP added to milk at 0, 4, 6 and 8% levels which reached the total solid of milk to 21.5%. KG with percentage of 0, 0.05, 0.1, 0.15, and 0.2% was added to the mixture at 40˚C. The mixtures were homogenized at 50˚C and pasteurized at 90˚C for 1 min. and then cooled to 43-45˚C. The mixtures were incubated at 43-45˚C for 3-4 hours after addition of starter. Then the samples were slowly stirred and packed in polyethylene bags after reaching to suitable pH. The samples were transfered to refrigerator for 24 hours then the tests were conducted. PH was measured according to AOAC 2005 official method NO. 935.42.25 gr of samples were centrifuged at 4˚C for 10 min. at 4500 rpm. Syneresis was evaluated as parentage of separated serum. Texture analyzer was used for combination of back extrusion and texture profile analysis (TPA) test. 50 mm in diameter cylinder with 10 mm in height and probe with 4 mm diameter and 100 mm height with the speed of 1 mm/s were used to conduct the test. Dynamic rheological parameters were evaluated by rheometer (Parphysica). The devise was equipped by 50mm diameter parallel plate with 2 mm gap. Eheo plus/32 version V3.40 software was used to measure elastic modulus (G’), loss modulus (G”) and η*. Results & discussion: Results showed that none of the linear, quadratic and interaction effect of MPC, CWP and KG was significant on pH of the samples at the first day. Results represented that the pH of the samples was varied from 0.36 to 0.94 after 5 days and only linear effect of MPC and CWP (at 99% level of confidence) and interaction effect of CWP-KG (at 95% level of confidence) were significant on that. The effect of MPC and CWP and interaction effect of MPC-KG, CWP-KG and CWP-MPC-KG were significant on syneresis at 99% of confidence. Results showed that hardness of the samples varied between 3.25-9.58 N and the interaction effects of MPC-KG, CWP-KG and CWP-MPC-KG were significant at 99% of confidence. None of the linear, quadratic and interaction effect of CWP, MPC and KG was not significant on springiness of the samples (p>0.05). In strain sweep test, two separated regions were distinguishable: linear viscoelastic (LVE) region that elastic and viscous modulus (G’ and G”) were constant and G’ was higher than G” which showed the solid like behavior, and non-LVE region that G’ and G” decreased by increasing strain and led to a crossover point (flowing point) which G” goes over the G’ and liquid-like behavior shows itself. In this test, strain corresponding to start of the non-LVE region and sharp reduction of G’ define as critical strain (γc) and the corresponding stress of this point defined as critical stress (τc).Results represented that G’LVE and G” LVE of the samples varied from 22.54 to 750.1 and 11.01 to 242.1 Pa, respectively and the selected model (cubic x quadratic) showed that the interaction effect of MPC-KG, CWP-KG and CWP-MPC-KG on G’LVE and G” LVE was significant at 99% of confidence while the interaction effect of CWP-MPC was only meaningful on G” LVE. Results also showed that the variation trend of G’LVE and G” LVE was the same by alteration MPC, CWP and KG in a way that both of these parameters were increased by increasing KG. The effect of MPC-KG and CWP-KG was significant on γc and τc at 95% confidence and also, in addition to mentioned effect, the interaction effect of CWP-MPC was significant only on γc. Increasing KG increased γc at higher amount of CWP and lower amount MPC which can be concluded that increasing KG amplified the gel strength. Also, the results of the correlation study between sensory and instrumental measures showed that there was a close relationship between the score of sour taste and the overall acceptance of samples, which showed that among the measured characteristics, sour taste score is more important than other parameters.
Hassan Rashidi; Mostafa Mazaheri Tehrani; Seyed Mohammad Ali Razavi; Mohsen Ghods rohani
Abstract
There is overwhelming scientific evidence that saturation fat consumption increases the risk of both coronary and cancer disease. As a result, fat reduction in UF-Feta cheese (≈ 45% fat in dry matter content) is favorable but unfortunately has some negative effects on the quality of cheese. In this ...
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There is overwhelming scientific evidence that saturation fat consumption increases the risk of both coronary and cancer disease. As a result, fat reduction in UF-Feta cheese (≈ 45% fat in dry matter content) is favorable but unfortunately has some negative effects on the quality of cheese. In this research, the effect of different levels of retentate fat (0, 2, 6, 10, 14 and 18%) and CaCl2 (0 and 0.02%) on sensory (texture, taste, odor, total acceptance) and mechanical texture (texture profile analysis and penetration parameters) characteristics of UF-Feta cheese made from retentate powder was studied. The completely randomized design with two factors was used for production and data analyzing. The results of sensory test showed that cheese sample containing 10% fat retentate and 0.02% CaCl2 had highest texture score with significant difference. Therefore, the panelists were preferred taste and odor of full-fat samples and the maximum total acceptance was belonged to cheese sample made from 14% fat retentate. In texture profile analysis, fat reduction was resulted in significant decrease in gumminess, chewiness, adhesiveness, springiness and compression work but cohesiveness of samples didn’t have any significant differences. In penetration test, hardness, apparent modulus of elasticity, adhesiveness force, adhesiveness and penetration force were decreased with fat reduction. As a result, addition of 0.02% CaCl2 to retentate was increased generally the texture profile analysis and penetration parameters.
Keywords: CaCl2, Cheese, Fat reduction, Feta, Texture
Mohsen Qods Rohani; Seyed Ali Mortazavi; Mostafa Mazaheri Tehrani
Abstract
In this study, ultrafiltrated Feta cheese was prepared from cow’s milk ultrafiltraton retentate and soymilk blend. Rennet and calcium chloride were used simultaneously as coagulant to coagulate cow’s milk proteins and soymilk proteins, respectively. Then, the effect of storage period on physical ...
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In this study, ultrafiltrated Feta cheese was prepared from cow’s milk ultrafiltraton retentate and soymilk blend. Rennet and calcium chloride were used simultaneously as coagulant to coagulate cow’s milk proteins and soymilk proteins, respectively. Then, the effect of storage period on physical (Texture Profile Analysis test, Penetration test), chemical (total solids, protein, fat) and sensory (flavor, texture) properties of samples was investigated in 3, 20, 40 and 60 days after production. The results showed that during storage period physical properties decreased for both Texture Profile Analysis test and Penetration test. But, sensory and chemical characteristics of the product during storage did not significantly change, the way that the flavor and texture scores of the last day were still higher than the middle and the product after two months storage well was usable.
Keywords: Soymilk, Retentate, CaCl2, Storage period, Cheese
Mohsen Ghods rohani; Seyed Ali Mortazavi; Seyed Mohammad Ali Razavi; Mostafa Mazaheri Tehrani
Abstract
In this study, soymilk curd (tofu) was produced and evaluated at three stages according to Iranian preference. In the first stage, the effect of soybean varieties (Williams & Habbit), production methods (Traditional & Recommended), and formulation (0, 10 and 20% cheese whey instead of water used in soymilk ...
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In this study, soymilk curd (tofu) was produced and evaluated at three stages according to Iranian preference. In the first stage, the effect of soybean varieties (Williams & Habbit), production methods (Traditional & Recommended), and formulation (0, 10 and 20% cheese whey instead of water used in soymilk production) on the qualitative and quantitative characteristics of tofu were evaluated.
In the second stage, fresh tofu was stored in brine or cheese whey containing salt at different concentrations (2, 4 & 6%) and the quality of tofu was then evaluated. In the third stage, the consumer preference and the consumption attributes were determined. The results shown that the best quality of tofu will be achieved when the Williams variety, the recommended method and 0% whey are used. Furthermore, the results indicated that the most appropriate storage medium is cheese whey with 4% salt. Such product can gain the 72% of the consumer’s acceptability.
Key words: soybean, soymilk, soymilk curd (tofu) and whey.
