Journal of Food Biosciences and Technology
Volume:10 Issue: 2, Summer-Autumn 2020

In this study the rheological and textural properties of Iranian white cheese produced by ultrafiltration technique containing gum tragacanth and xanthan gum each in the range of 0-0.1%, and basil seed and linseed mucilages each in the range of 0-0.2% were evaluated. According to the results obtained, values of Elastic (G/) and viscous (G//) moduli increased with increasing frequency sweep in all the cheese samples. G/ was always greater than G//. The values of G/ and G// in the samples containing 0.05% of gum tragacanth, 0.05% of xanthan gum and 0.1% of basil seed mucilage and containing 0.05% of xanthan gum, 0.1% basil seed and 0.1% linseed mucilage were maximum and in samples containing 0.1% of xanthan gum and 0.2% of linseed mucilage and containing 0.1% of gum tragacanth were minimum. By increasing basil seeds mucilage in the samples, hardness, cohesiveness, gumminess and chewiness increased in comparison with the control sample (p<0.01). According to the results obtained, for preparation of white cheese produced by ultrafiltration technique, using 0.05 % of gum tragacanth, 0.05 % of xanthan gum and 0.1 % of linseed mucilage, is recommended.

Sterols due to their properties might be considered as valuable products to be employed in food, pharmaceutical and cosmetic industries. Vegetable oils, namely canola, soyabean and sunflower seed oils, contain considerable quantities of phytosterols, mainly β–sitosterol. The aim of this research is to determine the effect of refining operations, particularly deodorization on this valuable class of compounds. Three popular and common vegetable oils were sourced from local refineries and were subjected to neutralization, bleaching and deodorization procedures. The sterols were determined by saponification of the oils followed by extraction of the nonsaponifiable matter, and isolation of sterols by TLC and their final qualitative and quantitative determination by application to gas chromatography apparatus. The results indicated that sterols are lost in neutralization, bleaching and particularly deodorization stages to some extend and some might be collected in the distillate after deodorization. The distillate that is considered as a valuable source of sterols might be purified and used in various applications and industries.

Bread is a particularly important staple food. It can be thus improved using different prebiotics like inulin and resistant starch. Food diets with sufficient prebiotic content can trigger the growth of the remaining microorganisms in the digestive system. These microorganisms are essential for human health. In this study, the effect of different levels of inulin and resistant starch (at levels of 2.5 and 5%) was investigated on a number of qualitative properties of baguette breads. A completely randomized design with three replications was used to analyze experimental data (except for staleness data which were analyzed using factorial experiment with a completely randomized design). Means were compared by Duncan's multiple-range test (α = 5%). The results showed that moisture, ash and fiber contents of bread samples were higher than control samples, whereas protein, fat, and pH were lower in the former. In addition, these additives improved sensory analysis scores, instrumental staleness, color analysis and volumetric analysis of samples. According to the results, the treatment that contained 5% inulin and 5% resistant starch was selected as the best treatment.

Milkfat has the highest price among all the edible oils and fats and plays a significant role in the economics, nutrition and physicochemical properties of milk and milk products. It can be admixed or replaced with less expensive oils and fats of vegetable or animal origins notably palm oils. Blending of edible fat with vegetable oils is a common practice in many countries to improve the physical and nutritional quality. Milkfat blends with palm oil and its fractions by 1, 2, 5, 10, 20 and 50% (w/w) level were prepared and subjected to various physicochemical analysis. The results showed that total saturated fatty acids were decreased, while oleic and linoleic acids as unsaturated fatty acids were increased in relation to added palm oil. The addition of palm oils caused slight increase in slip melting point, refractive index and red value indicated by Lovibond. Therefore Solid Fat Content (SFC) of oil blends with stearin fractions was higher than both palm oil and milkfat but blends with olein fraction had lower level, while the SFC of oil blends with palm oil was close to pure milkfat.

In recent years, increasing in the level of public health consciousness has led to a drastic decrease in the use of synthetic food preservatives. Therefore, there has been a growing demand for novel antimicrobials. Apart from that, finding low cost sources has been always an important issue for food marketers. The present study was designed to investigate in-vitro antibacterial activities of grape and pomegranate waste separately and in combination with broth dilution methods against two bacteria (Staphylococcus aureus and Escherichia coli). The utilized solvent, as an extractant, was hot water. The total phenolic contents of grape and pomegranate wastes were also evaluated. Results revealed that the hot-water extract of the mixed wastes was the most potent, with the MIC / MBC of 52 / 286 mg/ml against E. coli and 75/98 mg/ml against S. aureus. It was also observed that the pomegranate waste contained higher level of phenolic compounds (439±0.82 mg GAE/L) as compared to the grape waste (333.6±1.25 mg GAE/L). It also exhibited higher antibacterial activity (lower MIC and MBC against tested bacteria) than the extract of grape waste. These results suggest that by-products of grape and pomegranate that are inexpensive and available can be employed as a potential source of antibacterial compounds.

The aim of this research was to assess the effect of fat type and concentration as well as the continuous phase viscosity on the rheological properties of an oil-in-water (O/W) emulsion. Thus, sunflower oil and tallow fat were used as the dispersed phase of the emulsion both at 10 and 50% (w/v) and CMC solutions (at 0.1, 0.3 and 0.5% w/v) were acted as the continuous phase. CMC solutions and emulsions showed a shear-thinning behavior with increasing CMC or dispersed phase concentration. The rheological behavior of all samples was well modeled by Herschel-Bulkley, Power law and Casson equations. According to Herschel-Bulkley and Power law models, an increase in the consistency index and a decrease in the flow behavior index of all samples was occurred with increasing CMC concentration (0.1 to 0.5%), fat concentration (10 to 50%) and dispersed phase change from liquid oil to a solid fat. The obtained data were compared with Einstein, Larson, Pal and Dougherty-Krieger predicting models and the results showed that Larson model well described the flow behavior of emulsions with 10% fat content, and Dougherty and Krieger or Pal equations were fitted more with the experimental data of emulsions containing 50% fat content.

Food preservation is an action or a method of maintaining foods at a desired level of properties or nature for their maximum benefits. In general, each step of handling, processing, storage, and distribution affects the characteristics of food, which may be desirable or undesirable. Thus, understanding the effects of each preservation method and handling procedure on foods is critical in food processing. In this study, the essential oil composition, antioxidant activity and antibacterial activity of Rosa damascena Mill. under Kashan (Isfahan province, Iran) were evaluated. The essential oil was obtained by hydro-distillation and gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of 19 compounds with the major constituents including Nonadecane (44.74%), 9-Nonadecane (16.91%), Eicosane (10.40%) and Heptadecane (6.17%). Antioxidant activity was examined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays. The results showed good free radical scavenging capacity and IC50 value (the concentration of inhibitor) of the essential oil was 3.91±0.4 μL/mL. The disc diffusion method was employed to measure the minimum inhibitory concentration (MIC). The minimum bactericidal concentration (MBC) was measured, by using the wells in which no growth was observed. The essential oil of the Rosa damascena Mill. exhibited antibacterial capacity against staphylococcus aureus 250, and for Escherichia coli and Salmonella typhi with the MIC and MBC for staphylococcus aureus, Escherichia coli and Salmonella typhi 500 and 1000 μL/mL, respectively. The obtained Rosa damascena Mill. essential oil is a promising source of natural antioxidant and antimicrobial agent for foods and cosmetics applications.

In the present study, packaging of a greenhouse-grown tomato on the culture medium containing 0, 25, 50, 75 and 100% compost tea under modified atmosphere: MA (88%N2 + 8%CO2 + 4%O2) in polyethylene and nanosilicon-polyethylene bags was studied at 5°C for 30 days. Several quality parameters such as moisture content, pH, total soluble solids (TSS), titratable acidity (TA), Vitamin C content, texture, and respiration rate were evaluated after 0, 10, 20, and 30 days of storage. Data were then analyzed using three-factor (i.e. substrate, packaging film, and storage time) completely randomized design with three replicates by SPSS software. Results showed that in term of substrate, the treatments containing compost tea had a significant effect on the characteristics of tomato in comparison with substrate without compost tea. However, the different levels of compost tea did not show the same results for all experiments. In term of storage time, most of the characteristics had a decreasing trend; however, they were in the defined standard domain for these properties. In term of the type of film, nano film was superior to polyethylene film. These findings confirmed the extension shelf life and maintain the quality of growing tomatoes on the substrate containing compost tea packaged under MA in a nanosilicon-polyethylene film for one month.

In the present study, the effect of addition of flaxseed mucilage on the physicochemical and sensorial properties of semi-fat (1.5% fat) set yoghurt was evaluated. Yoghurt samples were incorporated with flaxseed mucilage at the levels of 0.00, 0.10, 0.15, and 0.20% and analyzed periodically for pH value, titrable acidity, viscosity, consistency, water holding capacity, syneresis, colour parameters, and sensory attributes during storage at 5ºC (1, 7, and 15 days). The addition of flaxseed mucilage in the formulation of semi-fat yoghurt significantly influenced on chemical, physical, and sensorial properties of semi-fat set yoghurt during storage period. The pH value of all the samples decreased and acid value increased during storage period. Viscosity, consistency, water-holding capacity of the yoghurt samples increased while the syneresis value decreased with increasing the amount of flaxseed mucilage and storage time. Flaxseed mucilage addition decreased L* value while increased a* and b* values of the yoghurt. The sensory attributes of yoghurt samples were also affected by the level of flaxseed mucilage, so that the sample containing 0.15% flaxseed mucilage was preferred in terms of all the sensory attributes tested by the panelists.

Quercus persica has a natural antimicrobial and antioxidant properties that are effective on pathogens and retard lipid oxidation. The aim of this study is using two concentrations of free and encapsulated forms (with two covers: maltodextrin + carrageenan and gelatin + carrageenan) of Q. persica extract (0.5% and 1%) in order to improve the shelf life of minced kilka at the refrigeration temperature. Chemical tests (Peroxide value, total volatile nitrogen, thiobarbituric acid, and free fatty acid) and microbial parameters (total viable count and psychrotrophic count) were carried out. Minced Kilka samples treated with encapsulated form of extract at the concentration of 1% showed significantly lower chemical changes as compared to other treatments during the storage period. The results of microbial examination indicated at different period (0, 4, 8, 12 and 16 days) that the treatments containing encapsulated form of extract showed improvements, however of the twelve days all parameters were outside of the standard range (7 log CFU/g). The results of this study indicated that the encapsulation of 1% showed better results as compared to other concentration employed and improved the shelf life of kilka.