Research and Innovation in Food Science and Technology
Year:2013 | Volume:2 | Issue:2|Papers Count:7

The purpose of this study was to investigate the effect of Lallemantia royleana seed gum on the properties of oil-in-water emulsions stabilized by whey protein using “Response Surface Methodology (RSM)”. For this purpose, emulsions with different whey protein concentrates (0.5_3%), seed gum (0-0.3%), and oil volume fraction (20-50%) were prepared. Several properties of emulsions including mean diameter of droplets, zeta potential, surface tension and interfacial properties were studied. Selecting an appropriate model, the response-surface graph was drawn. For each response, a second-order polynomial model was developed using “Multiple Linear Regression Analysis”. Results indicated that increasing the gum concentration from 0 to 0.15% the mean diameter of the droplets will be diminished but its further increase would enlarge the size of particles. Zeta potential analysis showed that the more concentration of resin emulsions the more negative zeta potential of emulsion will be. The optimum formulation was suggested to be: 0.12% Lallemantia royleana seed gum, 4.69% whey protein and 21.59% oil.

At the present research, the differences between proximate chemical composition, color parameters, and functional properties of “Fenugreek” and “Soy” flours were studied. Also the effect of pH changes on protein solubility, foaming capacity and stability, as well as emulsifying capacity and stability of two flours were investigated. Protein and fat content of defatted fenugreek flour were determined to be 51.4% and 1.24%, respectively; while in defatted soy flour they were measured to be 66% and 7.13%, respectively. The protein solubility and emulsifying capacity of soy flour was lower than fenugreek flour due to the high amount of fat content in defatted soy flour, and the difference between protein type in two flours. There was no significant difference (P<0.05) between other functional properties of flours. These results show high amount of protein content in the specific flour does not contribut to better functionalities in comparison with the other flours in all cases. pH changes had noticible effect on foaming capacity and stability, and also emulsifying capacity and stability of fenugreek flour, while only foaming capacity and stability of soy flour showed to be sensitive to these conditions. L* and a* parameters of fenugreek flour were lower, but its b* was higher than soy flour.

Whey proteins are of wide application in the formation and stabilization of food emulsions. However, due to their high sensitivity to environmental conditions they quickly lose their functional properties. Glycolation of whey protein fractions is one of the methods used to modify their structure and improve their functional characteristics. The present work was carried out with the aim to prepare whey protein- starch conjugates and investigate the effect of protein to polysaccharide ratio on the quality attributes of oil-in-water emulsion. The results indicated that surface electrical charge decreased by increasing starch to protein ratio. On the other hand, changes in the surface and interfacial tension did not follow a clear trend in response to altering the mass ratio of protein. The drop size distribution curves were monomodal and nearly normal for all samples and became noticeably sharp with minimum width at protein to starch ratio 1: 1. The finest and largest droplets were observed in the aforementioned sample and the one stabilized by modified starch, respectively. Studying the flow behavior of emulsions also revealed that starch containing sample exhibited the characteristics of near-Newtonian fluid, whilst the others were shown to have shear thinning pseudoplastic properties which became more distinct by increasing protein ratio leading to highest consistency index and lowest flow behavior index at %100 whey protein.

Wheat germ is a healthy nutritious food supplement that can prevent certain cancers and other health problems. In this study, the effect of raw and stabilized wheat germ addition on chemical characteristics and nutritional value of cake was studied. Raw wheat germ was stabilized then milled and added to the formulation of the cake by 5, 10, 15 and 20%.Nutritional characteristics of the cakes enriched with 20% wheat germ such as polyphenole, fatty acid profile and tocopherol content and some chemical characteristics such as acidity and peroxide value were evaluated and also sensory characteristics in all cakes containing wheat germ were investigated. Results showed that the amount of polyphenoles increased from 263.2 ppm in control sample to 326ppm and 296.19ppm in cakes containing raw and stabilized wheat germ, respectively. By adding 20% of wheat germ in the cake formulation, decline in saturated fatty acids and increase in unsaturated fatty acids- especially linoleic acid- was observed. An increase in the amounts of α and b-tocopheroles in enriched cakes was also observed. Control cakes had the highest acidity and peroxide values.

In recent years using fresh foods that have undergone minimal processing, has become widespread. The use of active packaging is a new method for preserving of these products.In this study, active starch-clay nanocomposite films with addition of cinnamon essential oil or potassium sorbate (0, 5, 7.5 and 10% on the base of dry starch) were prepared. The physical, mechanical and antimicrobial properties of the active films were evaluated. For the evaluation of antimicrobial properties of the films, Aspergillus niger was used as one of the important spoilage fungi of bread. The results showed that 5% of the antimicrobial additives didn’t any antimicrobial activity. However, by increasing the concentration of the additives, antimicrobial activity also increased. In the same amounts of both additives, the films which contained cinnamon essential oil had stronger antimicrobial effects. The addition of potassium sorbate increased water vapor permeability of the films. However, cinnamon essential oil, didn’t affect this property of the films. These results showed that the films could be used as an active food packaging.

Vacuum frying is a new technology that can be used to improve the quality attributes of fried food because of the low temperatures employed and minimal exposure to oxygen. In this paper, the atmospheric and vacuum frying of Reshte-Khoshkar (a traditional Gilan-Iran sweet cookie) were compared. Four pressure levels (47.4, 57.83, 70.1 and 101.325 kPa), with three frying times (130, 160 and 190 s) and three thermal driving forces (DT=40, 60, and 80oC, constant difference between the oil temperature and the boiling point of water at the applied pressure) were used for frying. The effects of frying time, vacuum level and frying temperature on physical properties, such as moisture loss, oil absorption, and shrinkage were investigated. Moisture loss and oil absorption of fried Reshte-Khoshkar were significantly affected by frying pressure, frying time and frying temperature. The results showed that the moisture content decreased with increasing the frying pressure, frying time and frying temperature and fat content increased. Interestingly, a strong relationship between water loss and oil content was observed in both techniques. Vacuum frying was shown to be a promising technique that could be used to reduce oil content in the fried Reshte-Khoshkar. Shrinkage was not directly related to the frying condition of Reshte-Khoshkar.

In this study, the total phenolic and flavonoid compounds, radical scavenging activity and reducing power of ethanolic and methanolic extracts of Eryngium caucasicum-Trautv-(a native vegetable of Iran) were evaluated. Also, the phenolic acids of methanolic extract were determined by high performance liquid chromatography. Total flavonoid content and antioxidant activities of the methanolic extract were higher than those of the ethanolic extract (p<0.05). EC50 for DPPH radical-scavenging activity was 119.66 for the methanolic extract and 42.13 mg/ml for synthetic antioxidant BHT. Ferric (III) reducing power of the extracts increased in a dose-dependent manner however BHT showed higher reducing power. Phenolic acids were identified by reversed-phase high performance liquid chromatography. Gallic acid, cholorogenic acid, caffeic acid and p-coumaric were found in the methanolic extract.Chlorogenic acid was the predominant phenolic acid in the extract (63.07 mg/100g DW). On the basis of the results, Eryngium caucasicum-Trautv-could be used as a novel food additive which is rich in natural antioxidants for food industry.