Journal of Food Technology and Nutrition
Year:2014 | Volume:11 | Issue:3 (43)|Papers Count:11

Introduction: Cheese has a complex structure with differences within the same variety that depends on the compositional factors and the changes occurring during ripening. Whitebrined cheese, its production and some physical, chemical, rheological and textural properties were evaluated during six months ripening in this research study.Materials and Methods: Standard methods were used to examine the influence of ripening period (at the end of each month during six months) on the characteristics of White-brined Golpayegan cheese (36 samples). The rheological and textural properties of the cheese were evaluated using a rheometer (the frequency sweep test) and a texture analyzer (the uniaxial compression test).Results: During ripening pH, total solid, protein and total nitrogen in total solid (TN/TS) of White-brined cheese were decreased while the amount of titratable acidity, fat in total solid, water soluble nitrogen in total nitrogen (WSN/TN) and non-protein nitrogen in total nitrogen (NPN/TN) were increased significantly (p<0.05). On the basis of the small amplitude oscillatory test and the uniaxial compression test during maturation, the storage modulus (G'), loss modulus (G"), fracture stress (sf) and firmness have been increased (p<0.05) while the loss tangent (tand) has been decreased (p<0.05). The fracture strain ( ef) was kept constant (p>0.05).Conclusion: The results showed that ripening time significantly affected the physicochemical, chemical, reological and textural properties of White-brined cheese.

Introduction: Recently antimicrobial nanoparticles such as ZnO have attracted the attentions of scientists. Regarding the antimicrobial effect and low cost of ZnO nanoparticles, these might be emplyed in food industry to reduce the growth of food microorganisms. The object of this study is to evaluate the antibacterial effect of ZnO nanoparticles on Bacillus Subtilis and E.Coli O157: H7, two important spoiling and pathogenic bacteria of food.Materials and Methods: ZnO nanoparticles have been synthesized by molten salt method and have been characterized by X-ray diffraction, and scanning electron microscopy. Bacillus Subtilis and E.Coli O157: H7 have been inoculated in 2% and 4% w/w ZnO containing tryptic soy broth followed by the plot of their growth curve.Results: Treatments with both 2% and 4% concentrations of ZnO nanoparticles significantly reduced the number of E.Coli O157: H7 (p=0.001 and p<0.001 respectively). However in the case of Bacillus Subtilis, the nanoparticles have significantly reduced the growth of the bacteria only in the concentration of 4% w/w (p<0.001), where as in concentration of 2% w/w significant reduction was not observed (p=0.537).Conclusion: Regarding the results of the present study, ZnO nanoparticles can significantly reduce the number of both bacteria however it seems that the effect for gram negative bacteria might be more dramatic.

Introduction: Oxidation of oils and fats might be considered as the main factor affecting the quality of the food in general. This process might be controlled by the application of different methods and means. Antioxidants are regarded as a tool to achieve this aim. Although the application of synthetic antioxidants due to their possible side effects might not be desirable, the application of natural antioxidants present in various food namely spices that have been consumed by man for years might be suitable alternatives. Therefore the aim of present investigation is to understand the antioxidant and chelating activities of chemical compounds present in ginger.Materials and Methods: Ginger extracts (Zingiber officinale Rosceo) were prepared by cold extraction using acetone and methanol as extracting solvents. Total phenolic compounds were determined and the extracts were added to tallow; a substrate free of natural antioxidants at concentrations of 0.02, 0.04, 0.06, 0.08 and 0.10 %. Peroxide value and induction period measurements were employed as means to determine the antioxidant activities of the extracts were compared to TBHQ, the synthetic antioxidant. The chelating activities of the extracts were determined by the application of copper in the form of 4-cyclohexyl butyric acid copper salt followed by the determination of peroxide value and induction period of the substrate.Results: The results indicated that the antioxidant activities of the extracts are concentration dependent and as concentration is increase better activity is observed. The acetone extract at 0.1% should a good activity ever better than the addition of 0.01% TBHQ. The acetone extract also exhibited chelating activity at 0.1%.Conclusion: Both methanol and acetone extracts of ginger exhibited antioxidant and chelating activities when added to tallow a substrate free of natural antioxidants.

Introduction: Thermodynamic properties of sugar solutions have important roles and uses in different industries such as food production, food preservation industries, while there is not enough experimental data for all of the properties of sugar solutions. Therefore, representing a method for prediction and calculation of the thermodynamic properties of these solutions might be helpful in food industries.Materials and Methods: In this study thermodynamic properties of important aqueous sugar solutions in food industries containing glucose, sucrose, fructose, maltose, manose, maltotriose, xylose and galactose have been studied using a developed thermodynamics model based on Gibbs free energy.Results: Different properties including water activity, sugar solubility, density, vapor pressure and boiling temperature of aqueous sugar solutions have been calculated using the Gibbs free energy based thermodynamic model proposed by Pazuki et.al.Conclusion: According to the number of experimental data used for different sugar solutions in this study for prediction of the solutions thermodynamic properties, it can be concluded that the model has a good ability to predict sugar solution's solubility, density and water activity. The comparison between the results proposed model results and the UNIQUAC model shows that the proposed model has a better agreement with the experimental data. It might be concluded that this model can be used for sugar solutions in food industries.

Introduction: Understanding the physical and mechanical characteristics and knowledge of agricultural products are important and vital and knowledge steps for post harvesting storage and preservation. In this study, several physical properties of the Qazvinian cultivars (Qazvini and Boein zahra) of pistachio nut and their kernel and the effect of different levels of moisture content on their characteristics were evaluated.Materials and Methods: Physical properties that consisted of dimensional specifications such as three major diameter (length, width, thickness), unit mass, sphericity, geometric and arithmetic mean diameter, surface area, true volume, true density, bulk density, porosity and the static coefficient of friction at five levels of moisture content (3.5%, 12%, 19.5%, 27%, 35.5%) were measured.Results: The results of this investigation concerned with geometrical properties indicated that moisture had significant effects on the dimension, geometric and arithmetic mean diameter, sphericity, surface area of pistachio nut and its kernel in both cultivars.Conclusion: By increasing the moisture content, all the listed properties of both cultivars (Qazvini and Boein Zahra) have been increased. The highest static coefficient of friction for Qazvini and Boein Zahra cultivars is on aluminum and the lowest is on plastic surfaces. The kernels of Qazvini and Boein Zahra pistachio, had the highest coefficient on wood and the lowest coefficient on plastic and glass surfaces respectively.

Introduction: Arachidonic acid (ARA) is an essential polyunsaturated fatty acid (PUFA) that plays important roles in human’s health. The species of Mortierella genus are able to produce a wide range of PUFAs and investigations have shown that production of PUFAs especially ARA is influenced by several factors. Recently, Microbial production of ARA by M. alpina, using solid state fermentation (SSF) has been of great attention.Materials and Methods: ARA production was performed on date waste by Mortierell alpina CBS 528.72 in solid state fermentation (SSF) by Plackett Burman Design (PBD). In order to provide an appropriate source of nitrogen, soybean meal was added. The effect of eleven variables including substrate particle size, initial moisture content and pH of substrate, carbon to nitrogen ratio of substrate, supplementation of soybean and linseed oil (LSO), inoculation age, incubation temperature and time, heating pre-treatment time and supplementation of the nitrogen on the fourth day, were investigated.Results: In the range of studied variables in this research, substrate initial moisture content of 70-75%, addition of 10 % (w.w-1) LSO, substrate particle size of 1.2-1.7 mm and addition of 4 % (w.w-1) nitrogen supplementations and inoculum age of 96 h, had significant effect on the increasing production of ARA. Maximum amount of arachidonic acid produced in this study was 4.66 mg.g-1 dry fermented substrate.Conclusion: By modifing the substrate and considering the above mentioned factors, a single cell oil with maximum amount of ARA by M. alpina can be abtained.

Introduction: Foods and beverages are usually packed in glass, metal, multi-layered paper and plastic containers. Nevertheless, during recent decades, polyethylene terephthalate (PET) containers have been increasingly used for packing not only beverages but also foods.Considering the importance of this issue that has a direct relationship with human health and bioenvironmental issues, this research is concerned with consumers' awareness in respect of advantages and disadvantages of packing types of foods and drinks. Moreover, the criteria for appropriate packing were investigated from consumer’s viewpoint.Materials and Methods: The applied tool of this research was a researcher-made questionnaire, that was prepared considering the ideas of the experts of this field along with structured interviews and the reliability was confirmed by the experts of this industry.Results: The results of the present work indicated that, although a large number of consumers are relatively aware of the disadvantages of PET containers, but it is inevitable not to use them.Conclusion: Lightness, ease of use, non-fragility, availability and inexpensiveness along with being the sole option in the market were some reasons for more usage of PET containers as compared to other packing containers. In terms of drinking water (mineral water) and beverages, lack of any other alternative products was the main reasons for using these containers.

Introduction: Probiotic apple juice is one of the newest product in healthy drink trade. The aim of this study is to investigate the survival of Lactobacillus acidophilus (LAFTI-L10 DSL) in both free and microencapsulated forms and also the effect of microencapsulation of the the physicochemical and sensory properties of apple juice during 60 days of storage at 25±5oC.Materials and Methods: This study consisted of four treatments: Control, apple juice containing Lactobacillus acidophilus in free form and encapsulated form and apple juice where the pH was regulated by the addition of whey protein to 4.4 with Lactobacillus acidophilus.Results: The results showed that the number of probiotics in apple juice containing Lactobacillus acidophilus in free and encapsulated form were reduced by two and one log cycle respectively and in apple juice where the pH was adjusted to 4.4 by whey protein using Lactobacillus acidophilus was increased by 1.2 log cycle during storage. The treatment concerned with whey powder showed the lowest transparency and color, while the encapsulated treatments showed the highest transparency and color and the lowest turbidity.Sensory properties of the samples containing free and encapsulated probiotic did not have significant differences as compared to the control Conclusion: It was concluded that the encapsulation might be used in the production of probiotic apple juice using Lactobacillus acidophilus.

Introduction: Diabetes mellitus (DM) is a metabolic disease that is clinically characterized by hyperglycemia. Flaxseed (Linum usitatissimum L.) is rich in health-promoting bioactive compounds namely alpha-linolenic acid, dietary fibre and proteins that can be useful for diabetic patients.Materials and Methods: In the present study the effects of flaxseed bread made with a mixture of flaxseed flour and wheat flour were evaluated on blood glucose of patients with type 2 diabetes. Flaxseed flour was incorporated in wheat flour. Flaxseed bread was included in the meals of thirty patients with Type 2 diabetes for 14 days. The blood biochemistry profile (BBP) was monitored before starting the study and at daily intervals.Results: The results showed that fasting blood sugar (FBS) in the experimental group decreased considerably (p=0.05).Conclusion: This study demonstrated the efficacy of flaxseed flour in the BBP of Type 2 diabetes. Intake of flaxseed bread caused a considerable decrease in fasting blood sugar in the patients.

Introduction: Early splitting Pistachio nuts in is one of the critical sources of aflatoxin contamination before and during harvest. In this research work physical characteristics, fungal, pest and aflatoxin contaminations were evaluated in early splitting pistachios.Materials and Methods: Physical characteristics, fungal contamination and aflatoxin content were assessed in pistachio nuts employing advanced methods. This study was carried-out using three varieties of commercial nuts consisted of Ohadi, Kalleghoochi and Ahmadaghaii.The data was analyzed in a randomized complete block design using Mstatc statistical analysis software.Results: The highest levels of Aspergillus infection was observed in early splitting pistachios with dry and semi-dry hull. These pistachios also had the highest levels of carob moth infestation and shell staining as well as low kernel weights. In early splitting pistachios with soft hull the fungal infection, carob moth and shell staining were 0.75-10.3%, 1.5- 9.5% and 21.5- 44.1% respectively. This indicates the critical effects of early splitting pistachios as well as the risk of aflatoxin formation. The results showed that the levels of Aspergillus infection are increased by the presence of carob moth and ants, while there was low kernel weight.Aflatoxin was not detected in pistachio with healthy hulls. On the other hand, shell and kernel of early splitting pistachios contain different levels of aflatoxins (P<0.05). Aspergillus flavus isolates was alike to produce 67% aflatoxins B1 and B2 and 24% aflatoxins B1 and 9% were nontoxigenic.Conclusion: Sorting out early splitting pistachios based on physical and appearance characteristics would reduce the levels of aflatoxins during or after processing. Early peaking is a critical factor to reduce fungal and aflatoxin contaminations. About 95% and 5% of aflatoxin contents were related to kernel and shell, respectively. Therefore, assessing the risk of contamination should be based on kernels.