Research and Innovation in Food Science and Technology
Year:2013 | Volume:2 | Issue:4|Papers Count:7

The present study investigated the effect of gelatin coating, containing ascorbic-acid (AA: 1% w/v) and Propyl-gallate (PG: 100ppm), on the instrumental and sensory properties of roasted pistachio (hardness and color). Pistachio nuts packed and stored at 35°C and 50°C. The changes occurred in the textural properties, moisture content, color parameter (‘L ’, ‘ a ’ and ‘ b ’values) and sensory attributes of pistachio nuts were determined during 3 months of storage.The instrumental properties were correlated with sensory attributes. Gelatin-antioxidants coating significantly (P<0.05) increased instrumental and sensory hardness of pistachio. The moisture content decrease with time in gelatin-antioxidants and antioxidant- coated samples.However, this value in gelatin-coated samples was significantly lower than another sample. In sensory evaluation of color, the effect of treatments was significant. The image-processing result revealed that color parametera * in green kernel beside L * and b * parameter in purple skin of kernel, was significantly increased in AA-gelatin coated pistachio. Using the gelatinantioxidants coating, brought better maintenance to the green color of the kernel (theΔE* factor lower than control sample) while it decreased the red-purple color of kernel skin (moreΔE* factor). The results indicated that there are strong relationships between the instrumental and sensory hardness values, but sensory and instrumental color values had a weak correlation with each other.

Probiotics and prebiotics play important role in improvement of the intestinal microbial balance and have a great potential for food industry and public health. Survival of probiotics during gastric stress is influenced by the prebiotic carriers. In order to introduce effective synbiotic pairs, in this study the prebiotic influence of inulin (extracted from chicory and Jerusalem artichoke and also standard lab grade inulin), glucose and non-carbohydrate sample were assessed on bile resistance and inhibition of two Lactobacillus species againstE.coli O157: H7. The effect of inulin treatments were studied on growth and viability of Lactobacillus caseiPTCC 1608 and Lactobacillus rhamnosus PTCC 1637 under various bile salts concentrations (0, 0.3, 0.5, 1, 1.5%) in completely randomized factorial design and the inhibition effects were evaluated using well- diffusion technique in completely randomized design, and compared with controls. Results indicated that extracted inulin could be effective on enhancing the bile salts resistance of two lactobacilli. This effect was decreased by increasing in bile concentration while longer inulin chains had less effect compared to glucose. Although the most antimicrobial effects belonged to glucose, standard and chicory inulin showed acceptable antimicrobial effects as well. Inulin from Jerusalem artichoke with the highest degree of polymerization showed the least effects.

The aim of this study was to investigate the influence of ultrasound and blanching pretreatments on oil uptake and to model them on potato slices during deep-fat frying.Ultrasound pretreatments were applied at 40 kHz for 20 and 40 min and blanching pretreatments were done in hot water at 80oC for 2 and 4 min. Then, frying processes were performed at 150, 170 and 190oC for 90, 180, 270 and 360 seconds. To model the oil uptake as a function of time, four experimental proposed models and two empirical models available in the literature were used. In addition to the time, the oil uptake was modeled as a function of moisture content, density and shrinkage. Results showed that blanched samples for 2 min had the lowest oil uptake at the frying temperature of 150oC. Furthermore, the combination of ultrasound pretreatment (at 40 kHz for 20 min) and blanching (for 2 and 4 min), decreased oil uptake at the frying temperatures of 150 and 170oC. Moreover, experimental data were fitted well with empirical models. In addition, for determining the coefficients of the oil uptake models, some correlations were found by multivariate regression analysis in various conditions of the frying process.

This study was to determine the effect of potato paste at two varieties and five levels of one, 2, 4, 8 and 10 % (w/w flour basis) on stalling properties of "Barbari" bread with a completely randomized experiment with factorial arrangement in 3 replications. Immediately, three and five days after baking, the moisture content of crumb and crust, the textural properties and the thermal analysis of bread were determined. In this study varieties of potato didn’t have any significant impact on shelf life of breads (p<0.05). Higher amounts of potato paste were able to reduce the dehydration rate of crumb and hydration rate of crust during bread storage. The evaluation results of texture showed that addition of potato paste reduced the firmness of breads and over time, these samples were softer than the other samples. Enthalpy thermal analysis has also showed lower retrogradation enthalpy in breads containing higher amount of potato paste.In conclusion 8 and 10 percent of potato paste in the Barbari bread formulation will retard the bread stalling.

In this study protein hydrolysate was produced from the crucian carp using Alcalase 2.4L.The effect of temperature (40, 45, 50 and 55oC), time (60, 90, 120, 150, 180 & 210min) and enzyme/substrate (Protein) at ratio of (30, 60 and 90 Anson unit), on degree of hydrolysis and antioxidant activity of product were investigated in a in a completely randomized design. The highest degree of hydrolysis was observed at 45oC, after 180min and enzyme/substrate ratio of 60 Anson unit/ Kg substrate. Under these conditions, degree of hydrolysis was 39.38 %. The antioxidant activity of protein hydrolysate was studied using DPPH radical scavenging activity, reducing power and Fe++chelating activity. The most DPPH radical scavenging activity was 57.5%, that was obtained at 45ºC, enzyme activity of 60 Au/kg and 150min of time of hydrolysis. Highest Fe++chelating activity (44.56%) observed at 45oC, enzyme activity of 60 Au/kg, and hydrolysis time of 180min. The highest reducing ability of protein hydrolysate observed at 120min. Hydrolysis time which showed 67.32% reducing power compared to 100 ppm ascorbic acid (100 %).

In this research, the use of Tween 20 nonionic surfactant in MEUF process was investigated in order to observe how should reduce the raw sugar impurities such as turbidity, color, total dissolved solids (TDS) and starch. Also, variations of the permeate flux were studied. The effect of parameters of temperature (in three levels of 30, 40 and 50oC), transmembrane pressure (in three levels of 2, 3.5 and 5 bars) and surfactant concentration (in three levels of 0, 1 CMC and 2 CMC) on removal value of the mentioned impurities in raw sugar was investigated by the Response Surface Methodology (RSM). The results showed that the use of Tween 20 surfactant leads to a better removal of color, turbidity and starch in raw sugar in comparison with conventional ultrafiltration process. However, it had not a great success on reducing the TDS. Also the permeate flux was decreased by increasing the surfactant concentration. The operational parameters in this research were effective on the variations of color, turbidity, TDS and starch with appropriate R2.

Gums are compounds that increase stability of mayonnaise by increasing the viscosity of the continuous phase. In this study, the Persian gum with carboxymethyl cellulose (CMC), at combination of levels 0: 100, 25: 75, 50: 50, 75: 25 and 100: 0, were used to produce treatments.Experimental data’s of color measuring showed that by increasing Persian gum level in samples, lightness (L*) and yellowness (b*) factors were decreased and increased, respectively.The samples included 100% Persian gum (1.5%w/w), and 75% Persian gum-25% CMC showed non-significant difference comparing to the sample contained 100% CMC (2%w/w). Sample with 75% Persian gum-25% CMC had highest hardness, cohesiveness and adhesiveness that had no significant difference compared with other samples. Rheological tests also showed that all samples had pseudo-plastic behavior at shear rates of 1-450 s-1 and weak gel-like behavior at frequency range of 0.1-10 Hz. Results showed that Persian gum has substitution ability at 75% and more than that with CMC in mayonnaise with no difference in the qualitative properties of the product.