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.
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
Amir Pourfarzad; Mohammad Bagher Habibi Najafi; Mohammad Hossein Hadad Khodaparast; Mohammad Hassanzadeh Khayyat
Abstract
Introduction: Fructans are an important product of the industry of prebiotics. In addition to their interesting nutritional and health benefit properties, fructans are also used in food formulations for their techno-functional properties such as fat substitute, bulk agent, water retention. Serish (Eremurus ...
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Introduction: Fructans are an important product of the industry of prebiotics. In addition to their interesting nutritional and health benefit properties, fructans are also used in food formulations for their techno-functional properties such as fat substitute, bulk agent, water retention. Serish (Eremurus spectabilis) belongs to the family of Liliaceae and geographically distributed in the region of South Asia and Central Asia. Their roots accumulate high levels of fructans during their growth and are traditionally used to cure jaundice, liver disorders, stomach irritation, pimples and bone fractures and even as a glue for industrial application. Recently fructan extraction from numerous plants and fungus has drawn the attention of researchers. Also, several methods for fructan extraction have been developed such as hot-water extraction, precipitation by alcohol and ultrasound-assisted extraction. To the best of our knowledge, there are no reports on the fructan extraction from Serish. The present study is considered the first attempt aiming to determine the optimal conditions for water extraction of Serish fructans. Materials and methods: The Serish root powders were obtained from the local medical plant market, Mashhad, Iran. Moisture, ash, fat, protein, Carbohydrate and total dietary fiber were determined according to standard AOAC methods. All variables were examined in triplicate. Conventional extraction was carried out in a water bath. Total carbohydrate was assayed colorimetrically using the phenol–sulphuric acid method. The concentrations of soluble reducing sugars were measured using a 3,5-dinitrosalicylic acid (DNS) method. The fructan content was measured by the difference between total carbohydrate and reducing sugars. The percentage of fructan yield (%) was evaluated based on equation of Lingyun, Jianhua, Xiaodong & Yalin (2007). The purity was evaluated according to the method of Paseephol, Small & Sherkat (2007). As an index of degree of polymerization, the average chain length, was calculated according to Lingyun, Jianhua, Xiaodong & Yalin (2007). A Box-Behnken design was constructed using the software Design Expert Version 6.0.10 and was used for estimating the effect of independent variables on the extraction parameters. Three extraction variables considered for this research were x1 (extraction time), x2 (extraction temperature) and x3 (water: solid) for conventional extraction method. Lack of fit, coefficients of determination (R2), adj-R2, coefficient of variation (CV) and significant probabilities were calculated to check the model adequacy. Optimization was based on generation of the best results for fructan extraction. In order to determine the validity of the model, the experimental and predicted values were compared by paired t-test. Results & discussion: It has a marked amount of protein and fats. The ash value is relatively high, suggesting an important mineral content. The composition of total fiber suggests its possible use as a source of dietary fiber for enrichment of foods. In addition, results show that Serish root powder is a polysaccharide-rich material. The results indicated that extraction temperature has the most effect on the extraction yield. Increase of time, temperature and water to solid ratio led to significantly increase in extraction yield. Considering the significant quadratic term of extraction time, it becomes clear that yield rises as extraction time increase from 0 to 22.5 min but it decreases at higher times. The yield increase between 0 to 22.5 min might be due to the time requirement for contact of fructan to the release medium where the liquid penetrated into the Serish powder, dissolved the fructan and subsequently diffused out from the root. On the other hand, the yield decrease after 22.5 min may be ascribed to degradation of fructan to free sugar and enhancement of impurities extraction at higher times. When extraction time goes by certain threshold, the yield started to decrease. The yield showed a large tendency to increase when the extraction temperature was increased. This is maybe due to the enhancement of the mass transfer resulting from the increased solubility of fructan and the decreased viscosity of the solvent. Yield was increased by portion of water to solid. This might be attributed to the availability of liquid that increases the driving force of fructan out of the root. Based on the sum of squares, temperature had the most effect on degree of polymerization. The results indicated that increase of time, temperature and W/S ratio resulted in increase of the degree of polymerization which might be due to the enhancement of overall carbohydrates extraction. On the other hand, the degree of polymerization of extracted fructan was lower than 10. This is probably because the disruption of fructan branch to reducing sugars with increasing temperature that leads to chain length decrease. Thus, the produced oligosaccharides could be used as sweetener. W/S ratio had the most effect on purity. The results showed that increase of time, temperature and W/S ratio resulted in increase of the purity which might be due to the enhancement of overall carbohydrates extraction. With the increase in extraction time, the purity of extract increased gradually, but decreased after the purity reached a maximum at 22.5 min. This decrease may be ascribed to degradation of fructan to free sugar and enhancement of impurities extraction at higher times. Multiple response optimizations were performed to measure the optimum levels of independent variables to achieve the desired response goals. Extraction yield and purity were desired maximal. Conclusion: The final results for this optimization was found to be extraction time of 28.38 min, extraction temperature of 88ºC and water to solid ratio of 50:1 v⁄w. Response surface methodology was an efficient statistical tool to model the influence of extraction conditions of fructan from Serish root powder on the extraction yield. These results also suggested that by modifying the proportion of these components, a large range of variations may be obtained. There was a good agreement between the experimental data and their predicted counterparts, showing the effectiveness of the proposed conditions and reliability of Box–Behnken analysis on fructan precipitation.
Amir Pourfarzad; Mohammad Hossein Hadad Khodaparast; Mahdi Karimi; Seyed Ali Mortazavi
Abstract
The effect of adding sodium stearoyl-2-lactylate (SSL) and propylene glycol (PG) (0 - 0.5 g/100g) to emulsifier gel formulation on the crumb and crust characteristics of Barbari bread fortified with soy flour in order to optimize these characteristics were evaluated. The obtained results showed that ...
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The effect of adding sodium stearoyl-2-lactylate (SSL) and propylene glycol (PG) (0 - 0.5 g/100g) to emulsifier gel formulation on the crumb and crust characteristics of Barbari bread fortified with soy flour in order to optimize these characteristics were evaluated. The obtained results showed that addition of SSL caused an increase in the crumb and crust L* and cell density. The a*, b*, average cell size and porosity of bread crumb decreased by increasing SSL. PG had increasing effect on b* of crumb and decreasing effect on L* of crust. However, no significant difference (p ≥ 0.05) was observed in a* and b* of crust. The results for optimization using central composite design suggested that a mixture containing 0.5 g/100g of SSL and 0.5 g/100g of PG could be a proper improver gel to achieve the best characteristics.
