Food Technology
Sima Naji-Tabasi; Elham Mahdian; Akram Arianfar; Sara Naji-Tabasi
Abstract
Introduction: Fats have a special place in human nutrition and their main role is supplying energy for the body. But scientific findings approve an association between high fat intake and an increment risk of some diseases, such as atherosclerosis, heart disease, and …. Demand for low-fat foods ...
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Introduction: Fats have a special place in human nutrition and their main role is supplying energy for the body. But scientific findings approve an association between high fat intake and an increment risk of some diseases, such as atherosclerosis, heart disease, and …. Demand for low-fat foods has increased dramatically as people become more aware of fat consumption side effects. However, due to the multiple role of fats in food products, eliminating or decreasing fat lead to poor quality of products. Therefore, it is necessary to use a combination of fat substitutes to maintain the rheological, texture and sensory properties of the low fat food products. The use of emulsion gel structures are new methods for the production of low-fat product that has been studied in this investigation. The Pickering emulsion was used to produce the emulsion. In this method, instead of using surface-active agents, solid particles are used to stabilize the emulsion. The aim of this study was to prepare Pickering Emulsion from Isolated Soybean protein (ISP) and Basil Seed Gum (ISP-BSG) Complex. Finally, emulsion gel systems were applied as fat substitutes in cream. Materials and Methods: Basil seeds were purchased from Mashhad market. Isolated soy protein was purchased from Shandong Yuxin Bio-Tech Co. (China). Sodium azide was purchased from Applichem Inc. (Dramstadt, Germany). Sodium dodecyl sulphate (SDS) was obtained from Merck, Germany. Pickering (solid particles) of soy protein isolate (SPI) and SPI-basil seed gum (ISP-BSG) complex used as emulsifier for stabilization of cold emulsion. ISP-BSG particles were prepared with different mass ratios of ISP: BSG, 1: 0, 1: 1, 2: 1 and 3: 1 and named 1S: 0B, 1S: 1B, 2S: 1B and 3S: 1B, respectively. These solid particles were used as Pickering for emulsion preparation. Cold Emulsion was prepared by adding calcium chloride. The oil leakage, oil leakage after thermal treatments, microscopic structure, textural properties and viscoelastic properties of emulsion gel were studied. Then, the best structures used as a fat substitute in cream (5, 10 and 15%). Results & Discussion: Investigation of emulsion gel properties showed that coating the surface of emulsion droplets with solid nanoparticles formed a rigid shell that acted as a barrier against the deformation and transfer of materials from the interfacial surface. The use of ISP-BSG nanoparticles as picking particles caused more homogeneity and stiffness in emulsion gel structure. The rate of water loss in reduced fat cream was in the range of 1-2% by using the emulsion-gel system, which indicates the effectiveness of these systems in reducing dehydration in cream. The increasing replacement percentages led to increase water loss (p <0.05). However, emulsion type had no significant effect on water loss content (p> 0.05). According to the results, ISP-BSG nanoparticles impart high potential to stabilize emulsion with small oil droplets. Based on the results of the sensory test, it was found that the characteristics of the cream samples depended more on the replacement rate than the type of system used as an alternative. The presence of a fat replacement system maintained the desired quality in low-fat cream samples. Most of the samples scored higher than 3, which indicate the high acceptance of low-fat samples.
Raza Bataghva; Massoumeh Mehraban Sangatash; Ahmad Ehtiati
Abstract
Introduction: Hypertension is the result of angiotensin converting enzyme (ACE) activity in the vessel wall membrane. This enzyme converts angiotensin I to angiotensin II which results in vessel wall stiffness and an increase in blood pressure. Inhibition of ACE activity is a therapy for hypertension. ...
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Introduction: Hypertension is the result of angiotensin converting enzyme (ACE) activity in the vessel wall membrane. This enzyme converts angiotensin I to angiotensin II which results in vessel wall stiffness and an increase in blood pressure. Inhibition of ACE activity is a therapy for hypertension. In addition to synthetic inhibitors, some bioactive peptides (which are the products of protein proteolysis) have been identified as ACE inhibitors. Bread is a widely consumed bakery product all over the world. During dough fermentation, yeast proteases hydrolyze wheat flour proteins to prepare amino acid for cell growth. Natural cereal proteases are considered to be the other sources of protease. Proteolysis produces peptides in dough, which are bake-stable and have physiological effects on human body. Soy protein is a valuable plant protein, reported to be a source of peptides with ACE inhibitory activity and can be used to induce diversity in peptide species during dough fermentation. In this study, a completely randomized factorial design was created to evaluate the effect of the type of soy protein derivative, wheat flour substitution level and fermentation time on the ACE inhibitory activity of dough bioactive peptides. Materials and Methods: Wheat flour was substituted with 3 soy protein derivatives, including soy protein isolate, extruded soy protein and soy protein hydrolysate at 5 and 10%. Moreover, fermentation time was adjusted at 30, 60 and 90 min. Dough aqueous extract was evaluated in terms of molecular weight distribution using SDS-PAGE technique. The extract was then filtered through 3KDa membrane to separate short-chain peptides (theoretically <30 amino acids). Peptide concentration was determined using UV absorbance difference. The peptide solution was tested for the degree of hydrolysis based on OPA complexation reaction and ACE inhibition activity using FAPGG as the reaction substrate at two peptide concentrations. The experiments were triplicated and data were analyzed by ANOVA and Fisher`s mean comparison test using MINITAB software. Results and Discussion: Based on the SDS-PAGE pattern, it was observed that samples had a high level of low molecular weight peptides fraction were those enhanced with extruded soy proteins and soy protein hydrolysate. This results indicated that the addition of soy protein derivatives led to a higher content of short-chain peptides compared with wheat dough. The results also showed that all the examined variables, i.e. the type of protein, substitution degree and fermentation time, significantly affected the degree of hydrolysis and ACE inhibition activity of the separated peptides. The maximum degree of hydrolysis was observed in samples with soy protein hydrolysate- which was expected to have greater peptides diversity. This might be the reason for the higher ACE inhibition activity observed for these samples. Addition of Soy protein extrudate resulted in a higher degree of hydrolysis compared with soy protein isolate revealing that the extrusion technique caused to increase the protein susceptibility to proteolysis during fermentation along with the higher content of broken amino acid chains. The higher wheat flour substitution level resulted in a higher degree of hydrolysis, while in the case of ACE inhibitory activity, it was not significant. Overall, longer fermentation time increase the degree of hydrolysis, but led to lower ACE inhibition activity, probably due to active peptides hydrolysis. Wheat flour itself had a high level of ACE inhibition activity at the shortest fermentation time, compared with composite flours, while this activity was reduced at extended fermentation time. IC50 was the highest for the samples containing soy protein hydrolysate, surely a benefit from the initial proteolysis. In conclusion, the wheat flour substitution with 5% soy protein hydrolysate substitution,would lead to reasonable ACE inhibition activity and is suggested for bread formulation with hypertension lowering effect. It also needs more research to be done in order to evaluate substitution degrees lower than 5%, because it was observed that peptides diversity was more important than high hydrolysis degree. Overall, soy protein extrusion enhanced proteolysis and short-chain peptides production during fermentation which is a better option compared with isolated soy protein.
Maryam Sadat Sotoodeh; Nafiseh Soltanizadeh
Abstract
Introduction: Over the last few decades, development of the industrial life has remarkably increased the demand for consumption of ready-to-eat foods. Deep fat frying is a fast and conventional method for cooking and due to creating crispy surface, soft internal texture, desired color and taste has popularity ...
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Introduction: Over the last few decades, development of the industrial life has remarkably increased the demand for consumption of ready-to-eat foods. Deep fat frying is a fast and conventional method for cooking and due to creating crispy surface, soft internal texture, desired color and taste has popularity among consumers. The main problem related to fried food products is the high oil absorption during deep fat frying that is harmful for human health and has negative effects on shelf life of the product. Therefore, the aim of this study was to investigate the role of breading particles size as well as the influence of addition of soy protein isolate in breading and batter layers on properties of chicken nugget. Material and Methods: First, breading was divided to three particle sizes. Sieves with mesh size 40 (0.42 mm) and 60 (0.25 mm) were used for separation of small breading. Also, sieves with mesh size of 18 (1 mm) and 20 (0.84 mm) as well as 10 (2 mm) and 12 (1.68 mm) were used for preparation of breading with medium and large particle size, respectively. Three percent soy protein isolate was separately added to breading with particle size of small, medium and large and used for production of chicken nugget. Also, 3% soy protein isolate was added to batter mixture and then nuggets coated with three different breading particle size without soy protein isolate. Breading pick-up, moisture content, cooking loss, porosity, oil absorption and penetration, color and textural properties of the chicken nuggets were then evaluated. Results and discussion: Based on the results, the coating of chicken nuggets with small breading size led to the product with the highest moisture content and lowest porosity, oil uptake, oil penetration and shear force. However, chicken nuggets coated with small breading size had the highest breading loss. After incorporation of soy protein isolate to breading, the highest hardness and lowest springiness, cohesiveness and gumminess were related to the nuggets coated with small breading size, however, chewiness was not affected by breading particle size. Breading with small particle size containing soy protein isolate caused the highest L*, a* and b* values in fried chicken nuggets. Addition of soy protein isolate to breading layer significantly caused a decrease in cooking loss, porosity, oil absorption and penetration (p < 0.05). These samples had higher moisture content than the control sample. After addition of soy protein isolate to batter layer, color of chicken nugget did not considerably change (p > 0.05). The effect of soy protein isolate on textural properties is dependent on breading particles size. Generally, the addition of this compound to batter layer decreased hardness, gumminess and chewiness; however, its effect on springiness and cohesiveness is dependent on breading particle size. The presence of soy protein isolate in batter layer increased moisture content which in turn could diminish porosity, cooking loss, oil absorption, and oil penetration (p < 0.05). Overall, the comparison between chicken nugget properties when soy protein isolate was added to breading or batter layer indicated that the presence of the protein in breading layer was more effective in retention of moisture, reducing of cooking loss, porosity, oil absorption and oil penetration. However, these samples had more hardness, gumminess and chewiness compared to those containing soy protein isolate in batter layer. Cohesiveness of chicken nugget containing soy protein isolate in breading was not significantly different with those produced with the compound in batter layer.The production of chicken nugget with small breading size containing 3% soy protein isolate in batter layer was proposed for production of products with better nutritional and physicochemical properties.
Hamideh Separdar; Ebrahim Rahimi; Iman Shahabi; Behzad Aghabarari
Abstract
Introduction : One of the most important problems of synthetic packaging of materials had been the time consuming process of their decomposition. Therefore, they have the potential to contaminate the environment. During the recent years, the above-mentioned problem has paved the way for developing biodegradable ...
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Introduction : One of the most important problems of synthetic packaging of materials had been the time consuming process of their decomposition. Therefore, they have the potential to contaminate the environment. During the recent years, the above-mentioned problem has paved the way for developing biodegradable biopolymers. One group of these polymers is films and edible coatings. Soy protein isolate is the purest type of soy protein which is available commercially and amount of its protein is more than 90% (based dry weight). These films have better nutritional value. In addition, they have better mechanical features and permeability than films made of carbohydrates and fats. Tragacanth gum is composed of two main ingredients under the name of Tragacantic acid or Basorin and Tragacantin. Basorin is in 60-70% of whole gum and is insoluble in the water. It can swell and make gel. Also, another ingredient or Tragacantin solves in the water and leads to make colloid solution. Hence, the main purpose of this work is studying effect of tragacanth gum as a supplementary and firmness-making material on physical and mechanical features of soy protein isolate film and are determining the best level of tragacanth gum and optimal film for using in food packaging.Materials and methods: A specified amount of soy protein isolate was solved in distilled water. Then, pH of solution was set on 10 by NaoH (0.1N). Solution of soy protein isolate was heated by bain-marie to 70˚c. Afterwards, solution of tragacanth gum with suitable amount of treatment which was solved separately in the water was added to solution of soy protein isolate slowly during agitating by magnetic mixer. Then, glycerol was added to the final solution as plasticizer. Final solution was agitated by magnetic mixer about 15 minutes to become smooth and pure. After degassing, the film forming solutions were casted by pouring the mixture onto polystyrene plate (10 cm diameter) and dried at 25±5˚c for 48 h in a laboratory oven and room relative humidity. Finally, the dried films were peeled off the casting surface. Film solutions were prepared from soy protein isolate with ratio of 0.5:4.5(A), 0.3:4.7(B) and 0.1:4.9(C), tragacanth gum: soy protein isolate and plasticizer of glycerol were prepared in 100gr water with ratio of 90% (w/w) dry weight. According to plasticizer effect of water, to uniform moisture before performing each test, all the films were conditioned inside desiccators containing saturated magnesium- nitrate solution to ensure a relative humidity 0f 50-55% at 25˚c ± 1 for 48 h.Tensile strength (TS) and elongation at break (EB) were conducted by using tensile evaluation machine (7010, Gotec of Taiwan) according to ASTM standard method D882-10 (ASTM, 2010).Films were cut in the dimension of 2×2 cm2 and dried to reach constant weight at 100 ˚C in a laboratory oven. Dried samples weighed to determine the initial dry weight (m1) and placed inside beaker including 50 ml of distilled water with periodic stirring for 24 h at 25˚C. Afterwards, the remained pieces of films were taken out and dried at 100˚C to reach constant weight (m2).After the films reached in moisture balance at 25˚C and a proportional humidity at %55. Their moisture was determined by measuring the loss amount of film weight during drying in a laboratory oven at 105˚c unti constant weight.The specimens of films was provided at 2×2cm2 dimensions and prepared by dried calcium chloride until reached to constant weight (m1). After the initial weight, they were conditioned in a desiccator containing saturated magnesium nitrate solution at 25˚c to provide reaching a relative humidity of %50-55. Then, the specimens were weighed in regular intervals until the equilibrium state was reached (m2).Water vapor permeability tests of films were performed according to ASTM- E95-96 standard (ASTM, 1995).The color of films was evaluated using a colorimeter device (LabscanXE, Hunterlab, USA). Statistical analysis was conducted in a completely randomized design with variance analysis (ANOVA) using SPSS software (Version 21; SPSS Inc., USA). Also, comparing the difference among mean values of film specimens was performed using Duncan,s multiple range tests at the confidence level of 95%.Results and Discussion:The obtained results indicated that tensile test (TS) of film was increased by increasing tragacanth gum and decreasing soy protein isolate but elongation to break (ETB) decreased. This result was agreed with the results of Fazel et al (2013), Tian et al (2011), Chen and Lai (2008). The amount of film moisture increased by increasing tragacanth gum, while amount of solubility in water, water absorption decreased by increasing tragacanth gum. The highest of wvp was observed in SPI:TG (4.9:0.1) but the lowest value was related to the sample SPI:TG (4.7:0.3). In general, the amount of wvp decreased by increasing tragacanth gum. The free space between chains decreases by forming transversal connections between protein filaments. Also, filaments mobility decreases, while penetration and spread of vapor molecules from polymer will decrease and its prevention becomes more in the water. The highest L, a, and whiteness index was observed in SPI:TG (4.5:0.5). In contrary, the highest b, total color difference (ΔE), and yellowness index was observed in SPI:TG (4.9:0.1). Optical properties of films used in food packaging are very important for their effects on acceptance and food quality. Results of Sarmadizadeh et al. (2014) showed that increasing protein has changed films color. Therefore, adding tragacanth gum caused to improve the structure and to improve physicochemical properties of the samples. It could be concluded biodegradable film of SPI+TG has desirable characteristics for the application in food packaging.
