Food Biotechnology
Zhila Ghasemi; Mohammad Alizadeh khaled abad; Hadi Almasi; Mehdi Nikoo
Abstract
Nowadays, probiotics have been seriously considered for their potential application in healthy food formulations. The most highlighted concern about probiotics is that the number of probiotic bacteria at the time of consumption may be lower than the required value (107 CFU/g). A new approach is the immobilization ...
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Nowadays, probiotics have been seriously considered for their potential application in healthy food formulations. The most highlighted concern about probiotics is that the number of probiotic bacteria at the time of consumption may be lower than the required value (107 CFU/g). A new approach is the immobilization of probiotic cells in the matrix of edible films. So in this study, edible carboxymethyl cellulose (CMC) probiotic films containing Lactobacillus casei, and the silver carp muscle protein hydrolysates (SCMH) prepared by using limited Alcalase hydrolysis, were analyzed and the viability of bacterial cells was determined at 25, 4, and -18°C for 30 days. An alkaline solubilization/acid precipitation method was used to isolate silver carp white muscle proteins. Protein isolate (3%, W/V) was hydrolyzed with 5% E/S ratio (w/w) Alcalase at 50°C and pH 8.0 for 3 min. Briefly, films were prepared by dissolving SCMH and CMC powder (1.5%, w/v) in a ratio of 1:2 in distilled water and L. casei was added to a final concentration of 108 CFU/mL. Probiotics were counted at intervals of 1, 10, 20, and 30 day. The physical, mechanical [Ultimate tensile strength (UTS) and elongation at break (EB)], thermal and structural properties were determined. XRD patterns of the film samples collected by X-ray diffractometer (XRD) and Fourier transform infrared (FT-IR) spectroscopy of the film samples were recorded. The results indicated that the addition of SCMH significantly (p˂0.05) improved the L. casei viability at all three temperatures. Thickness, moisture absorption, and water vapor permeability (WVP) of the films were not influenced by addition of the probiotic. However, the addition of SCMH negatively affected the film’s mechanical properties. The FT-IR analysis confirmed the formation of hydrogen bonds between L. casei and the CMC matrix, the XRD and differential scanning calorimetry (DSC) analyses confirmed the plasticizing effect of SCMH on the films. Thus, CMC films containing L. casei showed the highest UTS (3.7 MPa) and EB (29.9%). Generally, the results indicated that the SCMH incorporated CMC-based film can be a good carrier for probiotics as bioactive food packaging system with promising potential for shelf life extension of perishable foods.
Nasrin Faraji; Mohammad Alizadeh khaled abad; Hadi Almasi; Sajad Pirsa; Soheila Faraji
Abstract
Introduction: Fish oil is an omega3 source, because it consists of a long chain polyunsaturated fatty acids (PUFAs), namely Eicosapentaenoic acid (EPA, 20:5 n-3) and Docosahexaenoic acid (DHA, 22:6 n-3) that are essential to all humans and provide multiple health benefits associated with brain development, ...
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Introduction: Fish oil is an omega3 source, because it consists of a long chain polyunsaturated fatty acids (PUFAs), namely Eicosapentaenoic acid (EPA, 20:5 n-3) and Docosahexaenoic acid (DHA, 22:6 n-3) that are essential to all humans and provide multiple health benefits associated with brain development, cardiovascular disease, circulatory disorders, immune dysfunction and inflammatory disorders. The human body cannot make omega3 fatty acids on its own, so they must obtained from daily diet or supplements. Low uptake of this nutrient can cause serious problems. Lipid oxidation of fish oil and other PUFA-rich foods is a serious problem that leads to loss of shelf-life, consumer acceptability, nutritional value and functionality. On the other hands, omega3 cannot be incorporated into many functional foods, due to their poor water-solubility, chemical instability and low bioavailability, so some ways should be used to protect PUFAs such as microencapsulation and Nanoemulsion. The performance of low-energy methods has become very popular due to the lack of expensive equipments and ease of production. In this research, nanoemulsion of omega-3 fatty acids was prepared by spontaneous emulsification method using Iranian mentha longifolia essential oils. Material and methods: Fish oil was purchased from zahravi company comprised of 101 mg of EPA/g of oil, 148 mg of DHA/g oil, and 312 mg of total omega-3 PUFA/g of oil. Nonionic surfactants Tween 80 and Tween20 (Sigma Aldrich, St. Louis, MO, USA) and Sodium caseinate (MP Biomedical LLC. (Solon, OH) were purchased from chemical suppliers. Distilled and deionized water obtained from a water purification system (Milli-Q, Millipore, Darmstadt, Germany) was used to prepare all emulsions. All other chemicals used in this study were either Sigma-Aldrich (St. Louis, MO) or Fisher Scientific (Pittsburgh, PA). Iranian Shallot oil (penny royal oil) was purchased from magnolia company (Iran). The supplier reported the chemical composition as determined by gas chromatography-mass spectroscopy instrument (GCMS-QP2010 SE, GAS, Shimadzu, Japan). Factor A contains the omega 3 percent (25 to 75 percent), factor B contains surfactant-to-oil ratio (SOR %), (10-300 percent), Factor c contains surfactant type (Tween20, Tween80, T80:T20 and caseinate sodium) and factor d contains storage time (1-60 days) to achieve optimal production formula were selected. Physicochemical characteristics of Nanoemulsion including pH, peroxide value, turbidity, creaming index, D43, span, antioxidant, brix, refractive index and TBA were studied and Optimization of formula was performed by Response Surface Method (D-optimal design) The results were analyzed using design expert software (ver11). Results and discussion: Preparation of Nanoemulsion based on Iranian mentha longifolia oil loaded with omega 3 fatty acids by a low energy emulsification technique to protect it was evaluated in this study. The initial size of the droplets depended on surfactant type, surfactant concentration, storage time and omega3 concentration. Emulsions made of the highest surfactant concentration produced the smallest droplet sizes and were physically stable. It was found that the most important parameter effecting final emulsion responses was surfactant concentration. Our results showed that oxidative stability could be improved by the increasing surfactant concentration, also Iranian mentha longifolia antioxidant compounds were effective in reducing peroxide index and delaying oxidation. In all surfactants, by increase omega3 content, antioxidant activity was decreased. Results showed that all four examined variables affected the provided emulsion characteristics and the following conditions were obtained as optimum; storage time of 40 days, SOR %: 100, T80:T20 and omega 3 (29.31%). These nanoemulsions and essential oils can be applied to prevent undesirable off flavor fish oil and can be applied to fortify food or beverage systems with omega3 fatty acids.
Esmail Khazaei; Mikhalil Piruzifard; Fariba Zeynali; Mohammad Alizadeh khaled abad
Abstract
Introduction: Meat and meat products are important sources of protein, fat, essential amino acids, minerals and vitamins, and other nutrients. Bologna sausage, a cooked meat product, is one of the most accepted processed meat products and is consumed and enjoyed worldwide. Among the meat products, sausage ...
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Introduction: Meat and meat products are important sources of protein, fat, essential amino acids, minerals and vitamins, and other nutrients. Bologna sausage, a cooked meat product, is one of the most accepted processed meat products and is consumed and enjoyed worldwide. Among the meat products, sausage and bologna in vacuum packages due to their variety, easy to use applications and being economical, have become commonplace. The most important problem with the production, storage, and sale of this kind of meat products is their syneresis in the vacuum packages. In addition to an unpleasant appearance, syneresis leads to accelerating microbial growth and undesirable changes in the flavor and odor of the product.The addition of functional ingredients helps to modify the overall technological and sensorial characteristics of a meat system such as water holding capacity (WHC), fat holding capacity, and texture properties and decrease the syneresis. Syneresis and purge are seen as a result of retrogradation of starch and this is very common in sliced and vacuum-packed meat products. Storage of meat products containing high-amylose starches, at low temperatures from around –1 °C to 0 °C for a prolonged time also favors retrogradation. The level of retrogradation depends on the type of starch and wheat starch demonstrating the greatest tendency towards retrogradation. Chitosan is a natural cationic polysaccharide antibacterial activity and antioxidant properties in muscle foods during storage. The aim of this study was Investigation the addition of functional ingredients such as chitosan and potato modified starch in the formulation on the amount of syneresis, pH, total microbial count and sensory evaluation in two type of products including beef ham and chicken ham were examined during storage. Then, the effect of vacuum packaging type and the amount of vacuum created in the package on the amount of syneresis were investigated. Material and methods: In this study, first various factors such as three levels of chitosan (0, 0.3 and 0.6%) and replace the wheat starch with three levels of potato modified (0, 5 and 10%) in the formulation on the amount of syneresis, pH, total microbial count and sensory evaluation in two type of products including beef ham and chicken ham were examined during storage time (1, 15 and 30 days). In this part of the study, samples with the least syneresis were selected. After that various factors of packaging such as two types of vacuum packaging(simple vacuum pack and skin pack) and the amount of vacuum(5 and 30 millibars) created in the package on the amount of syneresis were examined during storage(1, 15 and 30 days). Wheat starch, potato starch, and chitosan were purchased, respectively, from Faradane Company, KMC Company, and Sinaseven Company. The chicken meat was purchased from Fileh Amol Company. The beef was purchased from the Minerva Company of Brazil. All steps of samples’ preparation were performed in the Kalleh Amol Meat company. The chicken ham samples in this study consisted of 90% of the chicken meat and beef ham samples consisted of 90% of beef. Vacuum packaging was done using the machines which were manufactured by the German company Multivac. Syneresis was measured using the method suggested by Cesare et al. (e 2013). The initial weight of the ham slices before vacuum-packed was measured (P1); on the day of the analysis, the packaging was opened and the slices were dried with a disposable absorbent towel, then the dried ham slices were weighed again (P2). Syneresis was expressed as Syneresis= (P1- P2) ×100/P1. This study was conducted in a completely randomized design and Duncan multi-ranged test was used to determine differences between samples at 95% confidence level. Results and discussion: According to the results of analysis of variance, there was no significant difference between the syneresis of beef and chicken ham. The effect of storage time was significant on the syneresis and the syneresis rate increased with increasing storage time. Also, the results showed that adding chitosan and potato modified starch significantly (p<0.05) reduced the product's syneresis during storage. Potato starch has more water storage capacity and more amylopectin than wheat starch. For this reason, potato starch has a weaker retrogradation and less syneresis. Chitosan is a cationic polysaccharide with water-absorbing polar groups. Chitosan also was prevented from decreasing the product’s pH during storage time, that this result showed the antimicrobial effect of chitosan on acid lactic bacteria, especially in 15 and 30 days of storage. For that reason, chitosan prevents product’s pH to reach to its isoelectric pH. According to the sensory evaluation results, during the maintenance period, the sensory quality decreased significantly while chitosan had a significant positive effect on sensory parameters during storage time (P<0.05). The type of vacuum packaging and the amount of vacuum created in the package showed a significant effect on the amount of samples’ syneresis. Skin packaging showed less syneresis rates than simple vacuum packages. This result can be due to two reasons: one is the shrinkage of the product in the package, and the other is the amount of the film packing tangency on the surface of the products. So that by increasing the amount of vacuum, syneresis value increased significantly. Increasing the negative pressure inside the package caused increase the mechanical pressure by the packaging film on the product. In total, it can be concluded that with the addition of modified potato starch and chitosan to the formulation, as well as the use of lower-vacuum Skin packaging, the amount of syneresis of meat products can be significantly reduced.
Nasibeh Obudi; Mohammad Alizadeh khaled abad; Sajad Pirsa
Abstract
A synbiotic yogurt was provided by adding aerobic (Lactobacillus acidophilus) and anaerobic (Bifidobacterium bifidum) probiotics and inulin to the yogurt. The effects of aerobic and anaerobic probiotics, storage time, and inulin on the physicochemical/microbial properties of synbiotic yogurt in terms ...
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A synbiotic yogurt was provided by adding aerobic (Lactobacillus acidophilus) and anaerobic (Bifidobacterium bifidum) probiotics and inulin to the yogurt. The effects of aerobic and anaerobic probiotics, storage time, and inulin on the physicochemical/microbial properties of synbiotic yogurt in terms of acidity, viscosity, syneresis, and microbial count were studied. A head-space solid phase microextraction-gas chromatography (HS-SPME-GC) method was used to extract and detect of VOCs profile (total peak area and total peak height) of yogurt sample by nano-sized polyaniline fiber. The D-Optimal Combined Design (DOCD) was used to analyze the effect of probiotics type (aerobic and anaerobic), inulin percent (W/W %), and storage time of yogurt (day) on the physicochemical/microbial properties of synbiotic yogurt. Results showed that the aerobic and anaerobic probiotics, inulin, and storage time of yogurt affect the yogurt physicochemical/microbial property and there were relations between the physicochemical/microbial properties of yogurt and VOCs gas chromatography profile (total peak area and total peak height). The current research also enables us to obtain microbial count by total peak area and total peak height of the VOCs GC-profile of yogurt sample.
Eisa Jahed; Hadi Almasi; Mohammad Alizadeh khaled abad
Abstract
Introduction: Due to increasing attention to the environment, as well as consumer demand for healthy, nutritive food products and extended shelf life, in the recent years, the food and packaging industries have paid increasing attention to biodegradable edible packaging prepared from biopolymers such ...
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Introduction: Due to increasing attention to the environment, as well as consumer demand for healthy, nutritive food products and extended shelf life, in the recent years, the food and packaging industries have paid increasing attention to biodegradable edible packaging prepared from biopolymers such as proteins, polysaccharides, and lipids or their combinations. These biodegradable films may act as carrier of wide variety of additives, such as antimicrobial, antioxidant agents, flavors, colorants and spices which improve the functionality of the packaging materials by addition of novel or extra functions. In the present study, an antioxidant/antimicrobial active packaging based on chitosan biopolymer was designed. For this purpose, lignocellulose nanofibers (LCNF) and cellulose nanofibers (CNF) at concentration of 4% were used as reinforcement of biopolymer properties, as well as to control the release of Origanum vulgare subsp. gracile and Carum copticum essential oils (as antioxidant/antimicrobial agent) from the packaging material into the foodstuff.
Materials and methods: The O. vulgare ssp. gracile leaves and C. copticum seeds were obtained from wild plants in mountains of Urmia (Iran). LCNF (average diameter about 55 nm, average length about 2–5 μm, 99% purity) produced from unbleached hardwood pulp through mechanical and acid treatments and CNF (average diameter about 28 nm, average length about 2–3 μm, 99% purity) prepared from softwoods through mechanical disintegration were kindly provided by Nano Novin Polymer Co. (Saari, Iran). Chitosan (medium molecular weight, from shrimp shell with a deacetylation degree of 75–85%), purchased from Sigma-Aldrich (St. Louis, MO, USA). Chitosan based bionanocomposite films incorporated with organic nanofillers and essential oils were developed by solvent casting method. The synthesized films were characterized by XRD and DSC analyses. To determine the prepared films would have potential to be used as an active packaging, water vapor permeability, water solubility, color, transparency, mechanical properties, antimicrobial and antioxidant activity of the films were also evaluated. In order to determine the efficiency of activated nanocomposites, the effect of these films was evaluated on the oxidative stability of rapeseed oil without antioxidants and compared with the effect of TBHQ synthetic antioxidant.
Results & Discussion: The results showed that the addition of essential oils did not have a significant effect on the crystallinity and thermal properties of the films, while organic reinforcement increased the crystalline properties and thermal resistance of nanocomposite films. By applying the essential oils and CNF and LCNF in the structure of the films, the apparent transparency and consequently the amount of light passage from them decreased compared to the control sample. With addition of essential oils separately and in combination, as well as CNF and LCNF in the structure of films, solubility and film permeability decreased compared to pure chitosan film. By adding of two essential oils with a ratio of 50:50, tensile strength (UTS) and strain to break (STB) of films were increased, while organic nanofibers led to an increase in UTS and a significant reduction in STB of nanocomposites. It was also found that active films containing different ratios of essential oil had remarkable antioxidant activity and high antimicrobial activity against E.coli and B.cereus bacteria, which by adding CNF and LCNF these features were reduced due to the role of controlling the release of essential oil compounds by nanofibers. With the numerical optimization of the software, the optimal amount for the essential oils of C. copticum and O. vulgare oils were 2.29 and 2.71% (5% mix) respectively, in combination with the LCNF nanofibers. The results of oxidative stability of Canola oil showed that nanocomposites containing 5% essential oil were considerably able to keep the oil freshness during storage at ambient temperature and delay the oxidation of the oil.
Ayda Saleh; Mahmoud Rezazadehbari; Mohammad Alizadeh khaled abad; Najmeh Sabahi Mohammadi
Abstract
Introduction : Yoghurt is one of the most popular dairy products in all over the world.Nowadays due to the tendency of consumers to use the products with healthy effects, probiotic and synbiotic products are considered. Yoghurt by itself is a healthy food; because of its high levels of protein and calciumcontents.Consumption ...
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Introduction : Yoghurt is one of the most popular dairy products in all over the world.Nowadays due to the tendency of consumers to use the products with healthy effects, probiotic and synbiotic products are considered. Yoghurt by itself is a healthy food; because of its high levels of protein and calciumcontents.Consumption ofprobiotic bacteria via food products is a way to reestablishthe intestinal microflora balance. Several studies have been done to improve the growth and viability of probiotic bacteria by adding supplements to milk.The objective of this study was to investigate the effect of three component mixture (Arabic gum, whey protein concentrate and milk protein concentrate) on quality indices of synbiotic yoghurt containing transglutaminaseenzyme. The content of theseprotein component, the amount of enzyme, enzyme addition time to the yoghurt samples and storage time were variableMaterials and methods:Yoghurt samples were prepared with milk which contained 2.5 percent fat.Milk was heated around 40 ̊C. WPC, MPC and Arabic gum were added to samples according to the research design and increasing the solid none-fat content of the milk up to 1.5%. Samples were pasteurized at 90 ̊C for 10 minutes in a water bath and were cooled rapidly to 43 ̊C for inoculation starter culture and probiotic bacteria. Also enzyme was added to samples before or after pasteurization (according to the research design).In this study microbial test was done to investigateviability of probiotics (BB-12) by differential culture medium (MRS-LP Agar). The titratable acidity was determined using 0.1 N NaOH until accessing the constant pink colour for 30secondes. Water holding capacity (WHC) was determined due to measure the protein quality of keeping water inside. Syneresis is expressed as the weight percentage of serum released by centrifugation. Viscosity was measured using a Brookfield viscometer.Viscosity measurementswere made using 250 mL ofyoghurt samples at 10 _CDiscussion & Results: The effect of WPC, MPC, Arabic gum, enzyme concentration and theaddition time of enzyme on viability of B. lactis (BB-12) for 21 days of cold storage at 4 ̊C were monitored. The results indicatedthat the effect of Arabic gum, WPC and MPC on viability of probiotic was significant (p
Forough Mohtarami; Mohsen Esmaiili; Mohammad Alizadeh khaled abad; Seyed Mahdi Seyedain Ardebili
Abstract
Introduction: A mixture of wheat flour, water, salt, yeast and other optional ingredients such as preservatives, enzymes, whey powder, surfactants, sugar, fibres and improvers form bread dough. Enrichment of dough and bakery products by dietary fibres such as wheat bran and resistant starch, beta-glucans ...
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Introduction: A mixture of wheat flour, water, salt, yeast and other optional ingredients such as preservatives, enzymes, whey powder, surfactants, sugar, fibres and improvers form bread dough. Enrichment of dough and bakery products by dietary fibres such as wheat bran and resistant starch, beta-glucans and inulin has been reported (Peressini, & Sensidoni, 2009; Hager, Ryan, Schwab, Gänzle, O’Doherty, &Arendt, 2011; Wang, Rosell, Barber, 2002; Angioloni, Collar, 2008). Whey has many applications in food and dairy industries due to its high quality of nutrients and functional properties. It possesses essential amino acids (Mann, 1998; Sharma, & Bhatia, 1999). There are other alternatives such as transglutaminase and asparaginase enzymes as innovative ingredients, which are recognized as safe in the food technology. The microbial transglutaminase enzyme (MTG) catalyzes the reaction between a ε-amino group of lysine residues and a β-carboxyamide group of glutamine residues, which causes to make covalent cross-linking of proteins (Yokoyama, Nio, & Kikuchi, 2004). Asparaginase (ASP) can catalyze the hydrolysis of asparagines, as a key factor for acrylamide formation, into aspartic acid and ammonia (Ciesarova, Kukurova, &Benesova, 2010). The present work was undertaken to study the influence of whey powder, inulin, asparaginase and transglutaminase enzymes on farinograph and extensograph properties of wheat flour dough using a D-optimal design.Materials and methods: Two types of wheat as insect damaged (50% insected) and sound hard red wheat (imported variety), milled into two types of flour by traditional mill. The characteristics of the flours such as moisture, ash, protein, falling number, wet gluten and Zeleny-value were determined using AACC methods (2000) in three replicates. Enzymes included MTG and ASP and other applied additives such as inulin (Frutafit-HD) and whey powder used at different levels based on flour weight in dough formulation. Effect of enzymes, additives and wheat flour types (WFT) on farinograph and extensograph characteristics were conducted according to the constant flour weight procedure of AACC (2000). D-optimal design was used to determine the effects of five independent variables including MTG, ASP, whey powder, inulin, and flour type on farinograph and extensograph properties. Response data were used to fit the second-order polynomial equation. Normal probability was used for separation of significant effects from noise or random effects. The significance of each coefficient in the regression model was determined using p-value lower than 0.05. Adequacy of models for regression were estimated using coefficient of determination (R2) and adjust R2 (adj-R2).Results and discussion: According to chemical and physical analysis of flour, it is obvious that in spite of having nearly the same amount of protein and wet gluten, the two types of flour had prominent difference in dough and gluten quality as indicated by gluten index and farino-extensograph tests. Due to this fact, the wheat flours with gluten index of 5.43±4.31 and 76.93±5.87 were named as weak and strong flours, respectively. Analytical data of farinograph properties were fitted to regression models. Analysis of variance of lack-of-fit test showed that the water absorption model is adequate with a non-significant lack of fit (p=0.267) and a satisfactory adj-R2 (97.53%). Among the different additives, strong wheat flour had positive effect and inulin and whey powder had negative effect on water absorption. According to half-normal plot and regression model coefficients, wheat flour type, inulin and whey powder significantly affected dough development time (DT) and stability (S). The models of DT and S had R2 values of 88.58%, 98.45% and non-significant lack of fits p=0.087 and p=0.018, respectively. DT and S increased with an increase in inulin and whey powder level using strong wheat flour. The regression model for degree of softening as a function of different ingredients was significant at a p-value less than 0.0001. Based on analysis of variance, the model appeared to be adequate with a non-significant lack of fit p=0.017 and a R2 value of 97.57%. Among the investigated factors, wheat flour showed the greatest positive effect on the degree of softening followed by inulin. The degree of softening was decreased by addition of inulin and whey powder. Among the interaction terms, a negative interaction effect on degree of softening was found between MTG and ASP (p
Hoda Khalesi; Mohammad Alizadeh khaled abad; Mahmoud Rezazadehbari
Abstract
Zedo gum is a polysaccharide that exudates from Amygdalus scoparia Spach tree. In this study the apparent viscosity under the influence of the gum concentration (0.5%, 0.75%, 1%, 2%, 3%, 4% and 5% w/v), temperature (20, 45, and 70 ˚C), pH (2, 5 and 8) and salt concentration (0-0.5 M) has been investigated. ...
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Zedo gum is a polysaccharide that exudates from Amygdalus scoparia Spach tree. In this study the apparent viscosity under the influence of the gum concentration (0.5%, 0.75%, 1%, 2%, 3%, 4% and 5% w/v), temperature (20, 45, and 70 ˚C), pH (2, 5 and 8) and salt concentration (0-0.5 M) has been investigated. Zedo gum is composed of soluble and insoluble components that respectively have the properties of solubility and swelling in water. The apparent viscosity changed due to temperature and pH. The highest viscosity was obtained at pH of 7.2 and 24 ˚C. Viscosity was changed by addition of certain strong electrolytes. The emulsion capacity and stability of oil in water emulsion increased by increasing gum concentration. Thermal behavior of Zedo gum with different moisture content was studied by differential scanning calorimetry (DSC). Thermal profiles showed an endothermic event. Considering the results obtained, Zedo gum is a potential natural and domestic additive for industry as a thickening agent, emulsifier and stabilizer.
Nasrin Faraji; Mohammad Alizadeh khaled abad; Asghar Khosrowshahi; Soheila Faraji
Abstract
Heart disease - cardiovascular, cancer and obesity are the main causes of death and there are direct relationship between the consumption of high-fat foods and the incidence of these diseases. Therefore the demand for low-fat food products and probiotics has been dramatically increased. In this study, ...
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Heart disease - cardiovascular, cancer and obesity are the main causes of death and there are direct relationship between the consumption of high-fat foods and the incidence of these diseases. Therefore the demand for low-fat food products and probiotics has been dramatically increased. In this study, the effect of different levels of three hydrocolloids (inulin, chitosan and xanthan) at three levels (1, 2 and 3%) on survival of Lactobacillus acidophilus, physicochemical and sensory properties of yogurt during 15 days of storage was explored using a combined design. Increased levels of inulin and chitosan positively affected La-5 count, apparent viscosity, acidity and sensory scores during storage. Using graphical method of optimizing (overlaid contour plots), optimum ratios were: inulin 93.4%, xanthan 0.6% and chitosan 6%.
