فصلنامه پژوهش و نوآوری در علوم و صنایع غذایی
سال دوم شماره 1 (بهار 1392)

The aim of this research was to study the feasibility of using Wheat Germ Protein Isolate (WGPI) and Xanthan Gum (XG) as egg substitutes in mayonnaise formulation. The mayonnaise prepared with different compositions of WGPI, egg, and XG by applying the optimal mixture design method and effect of this substitution on its stability, heat stability, viscosity, texture, physicochemical and sensory characteristics of mayonnaise were considered. In order to investigate the quality of mayonnaise during storage, stability, viscosity, pH, and acidity of the samples were determined during storage for 4 months. These parameters were in acceptable ranges, throughout the storage time, in all samples except for formulation 8 that contained 50% egg replacement with WGPI and without XG. The stability, viscosity, firmness, and cohesiveness increased with increasing the substitution levels of WGPI, although the appearance and color scores decreased. Generally, samples containing WGPI and XG, had acceptable quality in terms of investigated properties. However, the sensory characteristics of mayonnaise samples were decreased by increasing WGPI substitution. Mayonnaise with proper physicochemical and sensory properties was prepared by replacing %71.5 and %4.2 of egg by WGPI and Xanthan, respectively. Results showed the feasibility of preparation a low cholesterol mayonnaise by application a desirable combination of WGPI, XG, and egg, with comparable properties those of the conventional mayonnaise.

Postmortem proteolysis is one of the best ways to study meat tenderizing process. In this research, two groups of ostriches (male and female) were slaughtered by two

commercial (without electrical shock) and noncommercial (by electrical shock at 80 v/ 500 mA/ 10 s). pH decline of M. Gastrocnemius pars externa muscle was measured at 0, 1, 3, 6, 9, 18 and 24 hours and 3, 5, 7, 14 days during aging. Myofibrillar protein changes were evaluated at 1, 3, 5, 7 and 14 days postmortem by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Results showed that electrical stunning accelerated glycolysis rate especially at 1 to 3 hours postmortem (p<0.05). Female ostriches had faster pH decline (p<0.05). Myofibrillar patterns indicated that major changes was corresponded to the gradual degradation of troponin T from day 1 onwards and simultaneously appearance of 25 to 32 KDa peptides (p<0.05). Myosin Heavy Chain (MHC), α-actinin and desmin were degraded during storage period and polypeptides of 60 and 100 KDa were observed at this time. Because of accelerated pH decline, gender and slaughter conditions had significant effect (p<0.05) on degradation of most proteins that were substrates for calpaein enzymes.

Repeated uses of frying oil may cause oil deterioration due to subsequent hydrolysis and oxidation reactions. Oxidation products will expose the consumer health to serious dangers. In this project discarding time of canola oil during 40 hours potato frying in different conditions (temperatures 150, 165 and 180 0C, concentration 0, 50 and 100 ppm antioxidant TBHQ) was evaluated based on oxidation tests. Oil stability was determined by measuring acidic value (AV), peroxide value (PV), conjugated diene value (CDV), carbonyl value (CV) and total polar compounds (TPC). The results showed that after 34.1, >40 and 22.9 hours frying the PV, CV and TPC of canola oil respectively was maximum (based on national and international standards at temperature 150 0C). Increasing the temperature up to 180 0C, the rejection time based on these indexes decreased to 28.9, 35.4 and 16.4 hours, respectively. CDV of free antioxidant canola oil increased 592.1 % after 40 hours frying. It was 706.5 and 738.1 % for canola oil containing 50 and 100 ppm, respectively. Also, there was no significant difference between concentrations from 50 to 100 ppm in discarding time development.

Yoghurt is a fermented product (using lactic acid bacteria as the starter) with a short shelflife which its shelf-life can be prolonged by drying. Therefore, in this study, the effects of various parameters such as dry matter content (10, 20 and 28 %), microwave power (35, 135 and 260 W), type and combination of hydrocolloids added to initial yoghurt, as well as incubation of reconstituted yoghurt (37º C for 7 hours) on the color indices and the survival of starter bacteria in instant yoghurt were evaluated. The results showed that the higher microwave power and dry matter content of initial yoghurt the more contrary effects on the color of yoghurt powder and the number of starter bacteria. Based on our findings, the most appropriate dry matter content and microwave power were 10% and 35W, respectively. Moreover, the presence of hydrocolloids did not show any significant effect on the survival of starter bacteria. On the other hand, incubation of reconstituted yoghurt led to a significant reduction on the survival of yoghurt starter bacteria especially Streptococous thermophilous.

In this study, the beet pulp pressing water using nanofiltration process investigated. The effect of temperature (25, 40 and 55 ° C), the transmembrane pressure (10, 15 and 20 bar) and the brix (1, 2, and 30) on the rejection of sodium, potassium, calcium, magnesium, chloride and sulfate was studied. Then, physical modeling of sugar beet press water nanofiltration was performed by DSPM and compared with experimental data. The computer program of this model was written by MATLAB software (version 2008). In this modeling, ions rejection predicted based on ions properties (such as initial concentration, charge, coefficient diffusion and hydrodynamic radius), solution properties (such as viscosity and temperature), operating condition (TMP) and membrane properties (such as charge density, pore size and thickness of dense layer). The results showed that DSPM can highly predict the ions rejection under different operating conditions of sugar press water nanofiltration (R=0.970).

Recently by no incident there is a great concern in people to consume herbal antibiotics rather than using chemical ones due to bacterial resistances witnessed in chemical treatments. In this research the antibacterial activity of aqueous and ethanol extracts of black zira cell suspension culture in comparison with seed extracts and essential oils were investigated against Staphylococus aurous, Escherichia coli and Bacillus subtilis using disk diffusion and digging hole methods. The bacterial concentration was at 106 and 107 CFU/mL. Positive and negative controls were antibiotics (Gentamicin [10 μg/disk], Tetracycline [30 μg/disk]) and solvents (5% DMSO and 80% Ethanol) respectively. Inhibitory effects were studied by measuring the growth inhibiting circle diameter. The Results showed that the range of Minimum Inhibitory Concentration (MIC) were 3.12-6.25, 12.5-50 and 25-50 mg/ml, for the essential oil, the cell extract and the seed extract respectively. According to the results a promising antibacterial activities were revealed from all black zira samples against tested bacteria with the maximum activity to the S. aurous. In contrast to E. coli, the effect of extracts on S. aurous and B. subtilis was dependent to the bacteria concentration. Overall antibacterial effects of cell extracts against tested bacteria were lesser than essential oils (100%) and higher than seed extracts and different dilution of essential oils, therefore it seems cell suspension culture of black zira is a suitable method to produce antibacterial compounds.

The effect of soy protein isolate (SPI) at different levels, on quality properties (texture, color, water holding capacity and viscosity) and sensory evaluation of surimi prepared from common carp was investigated. Soy protein isolate was added at 10, 20 and 30 % levels to the common carp surimi paste and was heated at 90 ± 2⁰C for 30 min to produce a firm protein gel known as kamaboko. The results indicated that only addition of 10 % SPI enhanced the quality properties of surimi prepared from common carp (p<0.05). For instance, 10 % treatment enhanced the gel strength and WHC of surimi gel by about 6 % and 3.5 %, respectively, without significant reduction of whiteness of resultant gel. However, no significant (p>0.05) effect was observed in terms of texture profile analysis parameters. On the other hand, addition of 20 % and 30 % SPI onto surimi gel matrix reduced its functional properties. The best score in terms of overall popularity of resultant surimi gel were found to be for surimi including 10 % soy protein isolate, by the panelists. Finally, it can be concluded that SPI at 10 % concentration could potentially being applied as a protein binder in surimi gel network; however, it is not recommended based on its performance.