Food Biotechnology
Siamak Gheibi; Amir Pourfarzad; Ahad Rastkar Allahverdizadeh
Abstract
Introduction Marinated chicken meat is one of the traditional foods in Iran which is an indoor and outdoor popular food in different areas of Iran due to its convenience and pleasant taste. It is also one of the authentic foods which is categorized in Iranian traditional kebabs. This product is ...
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Introduction Marinated chicken meat is one of the traditional foods in Iran which is an indoor and outdoor popular food in different areas of Iran due to its convenience and pleasant taste. It is also one of the authentic foods which is categorized in Iranian traditional kebabs. This product is constituted of fresh pieces of chicken meat, diced in different pieces, marinated with salt, lemon juice, verjuice, vegetables, saffron, spices, fruits and oil and then supplied as fresh and/or frozen form. After the seasoning, it is grilled using a skewer. Therefore, it is necessary to investigate its microbial load, shelf life, and quality changes during storage. To the best of our knowledge, there are no reports on the chemical and microbial properties of processed chicken meat used as a factor to predict its shelf life. Thus, the present study was designed to examine the relationship between physicochemical, microbial and sensory properties of the marinated chicken meat during storage using symmetric multivariate (determination of correlation coefficients and principal components analysis) and asymmetric methods (partial least squares regression). Materials and Methods In this study, 30 samples of marinated chicken meat were collected from restaurants. Then, the asymmetric method (completely randomized factorial and partial least squares regression) and symmetric method (coefficients of determination and Principal components analysis) were used for the study of chemical (aw, TVN, pH, O/R) and microbial (total count, Staphylococcus aureusand Escherichia coli) and organoleptic characteristics of samples on the storage days of 0, 3, 6 and 9.An aw meter was used to measure the aqueous activity (aw), an automatic Kjeldahl device was used to measure total volatile nitrogen (TVN) and a pH meter was used to measure pH and redox potential (O / R). The dilution method was used to count the total bacteria. The cooked meat and bird parker media were used to identify Staphylococcus aureus. The MPN method was used to identify Escherichia coli. Sensory evaluations were carried out by 10 trained panelists. All assessors of the internal sensory panel assumed the basic odor test and color vision test. Each sample contained 50g marinated chicken meat, which was given to panelists in plastic containers at room temperature. The color, odor and overall acceptance of the marinated chicken meat were assessed. Each evaluator randomly evaluated the samples and served drinking water before each evaluation. Each parameter was scored in a 5-point scaling ranging from 1 (lowest) to 5 (highest). The data on the physicochemical, sensory and microbial properties of marinated chicken meat were statistically analyzed using Minitab 15 software (Minitab Inc., State College, PA, USA). The mean values of the treatments were compared by Duncan's multiple range test at a confidence level of 95%. Each experiment was performed in three replications. The PCA and PLSR modeling were also performed on the datasets. Results and Discussion Results from the statistical analysis suggest that the microbial and chemical parameters of marinated chicken meat were greatly capable of predicting its shelf life. Determination coefficients, principal components analysis (PCA), and partial least squares regression (PLSR) models are able to extract relevant information and offer an easy and promising approach for the interpretation microbial and chemical properties of samples and their correlation with shelf life. The obtained results indicated that three parameters including pH, redox potential and total count had the highest correlation with shelf life, recommended as the predictive components. The results of measuring water activity in chicken meat samples during storage at refrigerator temperature showed that the aw parameter did not change significantly during storage time in the samples while the pH, TVN and O / R parameters were significantly affected. Changes in the total count, Staphylococcus aureus and Escherichia coli were also significant during refrigeration. Sensory evaluation experiments showed that all samples had no signs of spoilage until the sixth day. ConclusionThe obtained results indicated that three parameters including pH, redox potential and total count had the highest correlation with shelf life, recommended as the predictive components. Overall, we can produce a product with higher quality and shelf-life if high quality raw materials are supplied with suitable pH values and also, hygienic production is considered.
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.
Fatemeh Heydari; Mohammad Javad Varidi; Mehdi Varidi; Mohebbat Mohebbi
Abstract
In the present study the cow meat was replaced with camel meat (0, 25, 50, 75 and 100%) in burger formulation. Principal component analysis (PCA) was performed to understand quality variables differences and similarities of thirty-five sample burgers. Score plot, represents Principal component analysis ...
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In the present study the cow meat was replaced with camel meat (0, 25, 50, 75 and 100%) in burger formulation. Principal component analysis (PCA) was performed to understand quality variables differences and similarities of thirty-five sample burgers. Score plot, represents Principal component analysis of datasets derived from evaluated variables of thirty-five samples (samples contain of 0, 25, 50, 75 and 100% camel meat). Overall, six principal component was obtained which 65.8% of the total variance was concentrated into three first PCs. Cooked L*, cooked b* shrinkage, springiness, flavor, texture, juiciness, color and overall acceptability were the variables which separated by the first PC. The PC2 is characterized by the rest of instrumental texture parameters and the third by cooked a* and fat. The evaluation of score plot shows burgers contain higher amount of camel meat (50, 75 and 100%) had the higher moisture and fat content after cooking, higher scores in flavor, texture, juiciness and overall acceptability.
Amir Pourfarzad; Mahdi Karimi; Zahra Ahmadian; Sudiyeh Hejri-Zarifi; Siamak Gheibi
Abstract
Introduction: Flat breads are the main dietary staple in many Middle Eastern and North African countries. In today’s demanding world, the use of bread improvers has become an indispensable part of enhancing the quality of bakery products. Bread improvers are technically sophisticated blends of functional ...
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Introduction: Flat breads are the main dietary staple in many Middle Eastern and North African countries. In today’s demanding world, the use of bread improvers has become an indispensable part of enhancing the quality of bakery products. Bread improvers are technically sophisticated blends of functional ingredients, which if formulated correctly, will enhance the development of dough structure, facilitate trouble-free production, and provide the desired result of consistent products having optimal quality at the lowest possible cost. Among the functional food additives, polyols have been increasingly used to improve the quality and shelf life of bread. Polyols have been used successfully to extend the shelf life of ready to eat bread used by the military, Barbari bread fortified with soy flour, as well as flour tortillas. Emulsifiers, a subset of surfactants, have been widely used by the baking industry. The function of surfactants, as crumb softening agents, is closely related to their interaction or complex formation with starch, particularly the linear amylose fraction, to retard bread staling. Surfactants, such as SSL and DATEM that are the most efficient in breadmaking are able to form lamellar mesophases or gel structures in water. It has been shown that for polar lipids the lamellar liquid-crystalline phase is the most effective form in which this component can be added to bread dough in order to improve loaf volume. Mechanical properties of dough play an important role in baking industries. In a few cases, it can be desirable, for example, to fix some ingredients on bakery products. The dough is expected not to stick to metal surfaces and to show a good resistance to vibration and mechanical shock to minimize detrimental effects such as process breakdown, production loss and contamination of the equipment. Thus, the present study was designed: (a) to examine the effects of different emulsifiers (sodium stearoyl-2-lactylate and diacetyl tartaric acid esters of monoglycerides) and polyol (propylene glycol) on Barbari flat bread performance when used singly and in combination at different levels; (b) to obtain the relationship between mechanical and rheological properties of dough and quality, shelf life, sensory and image parameters of bread using the asymmetric methods (response surface methodology and partial least squares regression) and symmetric methods (coefficients of determination and Principal components analysis) and (c) to determine the optimum formulations for Barbari flat bread improver.
Materials and methods: Commercial Triticum aestivum wheat flour (locally named Setareh) was procured from the AceeArd Co., Khorasan, Iran. Propylene glycol (PG) was purchased from J.T. Baker Chemical Company (Phillipsburg, NJ). Sodium stearoyl-2-lactylate (SSL) and diacetyl tartaric acid esters of monoglycerides (DATEMs) were provided by Vista Tejarat Company (Tehran, Iran). Moisture, ash, fat, protein, wet gluten and falling number were determined according to standard AACC methods. Three replications were taken for each characteristic. Gel samples were prepared using sodium stearoyl-2-lactylate (SSL), diacetyl tartaric acid esters of monoglyceride (DATEM) and propylene glycol (PG) in the range of 0-0.5 g/100g. Bread making was carried out according to the method of Maleki et al. (1981). Quality analysis of fresh bread samples was carried out by measuring specific volume. Sensory attributes of bread were selected according to the Iranian flat bread evaluation method, including bread form and shape; upper surface property; bottom surface property; cavity and porosity; firmness and softness of texture; chewiness; odor, flavor and taste and overall quality score. Staling phenomenon and its changes were evaluated by penetration test after 1 hour, 3, 5 and 7 days. The average values of L*, a*and b* colors describing the outer crust regions were obtained. The crumb grain features were the mean cell area, porosity, and cell density. A central composite design was constructed using the software Design Expert Version and was used for sampling of different combination of gel constituents. In addition, Lack of fit, coefficients of determination (R2), adj-R2, coefficient of variation (CV) and significant probabilities were calculated to check the model adequacy. Multivariate correlation matrix, coefficients of determination and principal components analysis were performed by using Minitab 15 software.
Results and Discussion: The characteristics of the flour are in the range of typical values of medium strong flour, suitable for Iranian Barbari flat bread. The results showed dough adhesiveness was increased by SSL addition but it was decreased by quadratic effect of SSL like as resilience. All of three components to the gel formula caused decrement in the hardness, gumminess and chewiness. But the interaction of them influenced on them. On the other hand, although cohesiveness increased by addition of all components but influenced significantly by interaction of them. Dough mechanical properties were furthermore correlated with dough farinographic aspects, quality, sensory parameters, image processing and shelf life of bread. It was proved that principal components analysis (PCA) is able to extract relevant information and offer an easy and promising approach for the interpretation of dough mechanical properties and its correlation with other properties and dough and bread. Partial least squares regression (PLSR) models were applied to determine the relationships between dough mechanical properties and dough farinographic properties, bread quality, sensory, image processing and shelf life aspects. Results from statistical analysis suggest that the mechanical parameters of dough are capable in predicting more than 50% of dough and bread properties
Narges Samanian; Seyed Mohammad Ali Razavi
Abstract
Sensory evaluation of food materials is an important factor to choose and even produce new formulations. Being time consuming, results in being difficult to interpret and the necessity to educate specialists make these methods kind of impractical. In this study, we have made an effort to introduce physical ...
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Sensory evaluation of food materials is an important factor to choose and even produce new formulations. Being time consuming, results in being difficult to interpret and the necessity to educate specialists make these methods kind of impractical. In this study, we have made an effort to introduce physical properties as a substitute for sensory evaluations in a semi solid food such as chocolate pudding. Higher reliability, reproducibility and higher pace are among some of the advantages of instrumental measurements. Thus, if sensory evaluation can be predicted based on physical properties solely, besides increasing the inspection pace, they would be available to be used online. The obtained results can also be used in designing new products for special consumers such as the dysphasia patients. The results showed that parameters such as shear viscosity, plastic viscosity, yield stress, extensional viscosity, apparent modulus and adhesive force can be used to design and produce new materials; they make sense beside each other though. In this way, the products which have been designed for the patients with swallowing difficulties should have suitable texture in mouth and also good swallow ease.
