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Showing 5 results for Najaf Najafi


Volume 15, Issue 80 (10-2018)
Abstract



Volume 16, Issue 87 (5-2019)
Abstract

Production methods of concentrated yoghurt (labane) varied from traditional methods, which are tedious, such as separation of whey by fabric bags, to complicated methods. These raise demand to establish more suitable methods such as “wheyless process” by dried milk, concentrated milk protein or concentrated whey protein. So the influence of different ingredients such as milk protein concentrate (MPC), whey protein concentrates (WPC) and konjac gum (KG) on rheological properties of labane was investigated through mixture-process design methodology and optimized these properties by firefly algorithm. The results of the combination of back extrusion and texture profile analysis (TPA) indicated that increasing KG significantly increased hardness, adhesiveness and adhesiveness force especially for samples with high amount of CWP but increasing MPC and decreasing CWP decreased cohesiveness in samples with high amount of KG. Strain sweep test of the labane indicated that all sample had gel-like structure (weak gel) at 1 Hz and 20˚C. Rheological results also showed that increasing KG significantly increased G’LVE, G” LVE, γc, τy, τf and Gf especially for samples with high amount of CWP. The optimal results of different gum percentages to achieve maximum Hardness, Cohesiveness, G΄LVE, γc, τy, tan δ LVE, Gf and minimum Adhesiveness, Adhesiveness force, G˝LVE using the firefly algorithm in PC space, it has been shown that the optimum amounts of KG and MPC were close to each other and had more variance of the data which shows the similarity of the effect of these two component on the rheological parameters.


Volume 16, Issue 87 (5-2019)
Abstract

In this research, the effects of Konjac gum (0.2-0.6%), Fat content (18-25%) and Homogenization pressure (100-200 bar) on rheological properties of low fat cream were investigated. The results of the back extrusion test indicated that increasing konjac gum, fat content and homogenization pressure, significantly increased hardness, consistency and adhesiveness. The simultaneous increasing of homogenization pressure and fat content also led to increasing adhesiveness of the samples, which showed their synergistic effect of them on the adhesiveness. The results of the steady shear test showed that the flow behavior index (n) of all samples was less than one which indicates a shear thinning behavior (pseudoplastic) of all samples. Also increasing fat content, significantly decreased the flow behavior index of the samples and increased the consistency. konjac gum and homogenization pressure had no significant effect on the flow behavior. The optimum processing conditions for producing low fat cream with the high hardness, consistency, consistency coefficient and low flow behavior index for response variables were 146/51 bar homogenization pressure،18/01% Fat content and 0.59% konjac gum.

Volume 16, Issue 88 (6-2019)
Abstract

Plant seed mucilage is one of the most important hydrocolloids used in food industry due to the ability to create structure and texture, properties of emulsifying, thickness and dietary aspects. The aim of this study was to investigate the effect of quince seed mucilage replacement on physicochemical (pH, specific gravity, melting resistance and overrun), textural and sensory properties of vanilla ice cream. For this purpose, mucilage was used as a substitute for carboxy methyl ellulose in ice cream formulation at 5 levels (0, 25, 50, 75 and 100%). The results showed that with increasing replacement ratio, the amount of melting resistance, specific gravity and overrun significantly increased (p<0.05). Addition of mucilage did not have a significant effect on the pH of the ice cream mixture (p>0.05). Adding mucilage reduced hardness (p<0.05). Based on sensory evaluation results, adding mucilage increased the total acceptance of ice cream. In general, and considering all the characteristics, it can be concluded that the sample with 100% mucilage substitution had a higher quality than other treatments.

Volume 18, Issue 117 (November 2021)
Abstract

In this study, the effect of different amounts of flaxseed extract (0, 2.5, 5, 7.5, 10, 12.5 and 15%) on the physicochemical and rheological properties of kashk was investigated Then, in order to better understand the effect of flaxseed extract on the evaluated properties, Sensitivity Analysis (SA) of selected regression models was performed. The results of analysis of variance showed that the effect of flaxseed extract concentration on moisture, fat, protein, pH and solubility of kashk samples was significant so that according to the results of sensitivity analysis for each one percent increase in flaxseed extract about 4.38% moisture, 11.82% fat and 0.78% pH of the samples increased. Also, for each increase of one percent of flaxseed extract, about 7.01% of protein and 2.72% of solubility of samples were reduced. Therefore, according to the results of sensitivity analysis, fat had the highest sensitivity and pH the lowest sensitivity compared to physicochemical properties to changes in flaxseed extract. Also, the results of analysis of variance of the samples showed that the effect of flaxseed extract concentration on all parameters of Herschel model (flow behavior index, consistency coefficient and yield stress) was significant So for each one percent increase in flaxseed extract about 9% consistency coefficient and 11.82% fat and 9.03% the yield stress of the samples increased.

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