Iranian Food Science and Technology Research Journal
Year:2009 | Volume:5 | Issue:1|Papers Count:11

The effect of different solvent systems on the extraction of antioxidant and anti radical agents of grape seed was studied. For this purpose 6 different solvent systems with similar polarity and different selectivity were used to prepare grape seed extract. Extraction efficiency, reducing activity, radical scavenging property and the effect of each extract on the increase of thermal resistance (oxidative stability index) of antioxidant free soybean oil were analyzed in the form of factorial test in a totally randomized design with triplicate repetition. Reducing activity test proved that grape seed extracts (GSE) had a higher reducing strength compared with BHT and a-Tocopherol except for ethylacetat treatment which had no significant difference between the extracts. Results of radical scavenging activity were similar to reducing activity results. The evaluation of oxidative stability index showed that acetone treatment has had the maximum Carry-through properties.

Compressed biscuits (CBs) were developed using wheat flour, soy flour, sugar, oil and malt extract. Combining of compression and dehydration technology were applied for production. Packaging CBs using vacuum packaged, use of oxygen absorber (OA) and identical samples were aerobically packaged and stored at ambient and elevated (40oc) temperature for 12 weeks. The effect of different packaging and temperature on chemical (FFA, peroxide value, aw and pH) and sensory (taste, texture and overall acceptability) characteristics of CBs was examined during storage. Free fatty acid (FFA) values showed no significant differences for all packaging treatments. According to peroxide values (PV) oxidation rate in aerobically packed CBs was the highest. These data suggest that OA were effective in prolonging the lag time before the PV started to build up. During storage a decrease in aw and pH values and an increase in FFA and PV values were observed. Although elevated temperature accelerated all chemical reactions but all chemical parameters met national standards. Evaluation of sensory characteristics showed that storage temperature and packaging method had no significant effect on sensory quality of the samples. The good correlation between the PV and taste scores evaluated by panelists suggested that oxidation is one of the main reasons of off flavor in CBs. Overall, the developed compact biscuit was stable at least 12 weeks in all packaging treatments.

The demand for low fat snacks is increasing. There are different methods to produce low fat fried products. One of these methods is coating. In this study effect of Carrageenan, oil temperature and frying time, on oil uptake of fried products (chips and strips) has been evaluated. Samples were deep fried in frying oil (Palm olein) at 160, 175 and 190oC. In order to evaluate the effect of frying time on oil uptake, potato strips coated with 1% Carrageenan were fried for 1 to 10 minute, then oil uptake has been measured. Results showed that Carrageenan as a hydrocolloid coating, reduced oil uptake in fried potato products compare with control samples. Coating potato slices with 1% Carrageenan led to significantly reduction in oil uptake tp<0.05) which was 37.23, 41.10 and 43.67 (%) at 160, 175 and 190°C respectively, whereas this amount for control samples was 43.27, 47.2 and 49.53 (%) respectively. For potato strips coated with 1% Carrageenan, oil uptake at above oil temperature was 12.17, 14.43, and 18.63 (%), whereas this amount for control samples was 17.60, 20.83 and 23.13 (%) respectively. Increasing oil temperature in a specific frying time led to significantly increase in oil uptake (p<O.05). Frying samples for 1 to 10 min, led to significantly increase in oil uptake (p<0.05).

Some wastes especially wastes of food industries need to be treated in order to recover some value-added products. One of these valuable products is biological pesticides. Today, the most successful biological pesticides are produced by Gram-positive, rod-shape bacteria, the genus Bacillus that produces crystalline endotoxin proteins during spore formation. These toxins will be activated when they enter the insect intestine under alkaline condition and will damage the cell membrane and make holes in the membrane which result in lysing of epithelial cells. In this research, the waste of starch producing industry was inoculated with Bacillus thuringiensis var. kurstaki and then the crystalline protein with MW of 65 KDa was produced during fermentation. The larvaes of Galleria melonella were treated to this protein and the rate of mortality was assessed after 24 and 48 h, and its effect was compared with that of control.Researches showed that the production of delta endotoxin has direct correlation with sporulation. The most toxicity of these bacterial proteins occurs at the highest number of spores. Thus, the number of total bacteria and their spores were enumerated using PCA during fermentation that was 12.5×108 and 48×107 cfu/ml, respectively.

Color and appearance are among the first parameters perceived by consumers to judge the quality of foods. L*a*b* are used to report foods' colors quantitatively. In this study the use of digital imaging and Photoshop software was evaluated for measurement of L*, a* and b* color parameters. The results showed that L*, a*, and b* values from Hunter colorimeter and the digital imaging method had a good correlation with R2 more than 0.95, but the values from digital imaging method can be used only to monitor the trend of color changes and the actual numbers of digital imaging L*, a* and b* obtained by digital imaging do not have the same value as the L*, a* and b* given by a Hunter colorimeter. Using two equations for the three parameters the values obtained from digital imaging method can be successfully converted to Hunter Lab color corresponding parameters. The color change of Mazafati date during accelerated ripening using acetic acid solutions was monitored by the proposed method. L*, a*, and b* of the samples all decreased over the ripening.

Probable use of chemical and biochemical detergents to wash polysulphone membranes using in milk ultrafiltration needs a multidisciplinary investigation. By increasing use of these membranes in food processing, washing and recovery of initial permeate flux, in order to use for a longer time from this technology, has much importance. In this research, influence of chemical detergents including EDTA, SDS and NaOH, biochemical including protease and lipase on recovery of permeate flux of ultrafiltration from polysulphone amide with pore size of 20 kD as a function of temperature, pressure, and time were investigated. Optimum amounts of activity of Protease and Lipase in temperature, pH and time of incubation were measured. Results showed that lipase cannot recover permeate flux and usefulness of this enzyme is not comparable with protease. With respect to the results obtained about optimum concentration of enzymes in recovery permeate flux, optimum concentration of chemicals in washing polysulphone membrane including EDTA, SDS, and NaOH were measured. Also, efficiency of optimum rate to mix enzyme, SDS and EDTA to recover flux and chemical used in industry were evaluated. Results showed that biochemicals (enzymes) are able to recover at least 60% of initial flux membranes. This rate for chemicals and under continuous and turbulent flow has been reported to be more than 95%.

One of the most important stages in sugar industry that making wastewater and contamination is the water obtained to washing of CO2 in mazoot furnace and related pumps. Amount of water consumption in this stage is about 30 to 35 percent of weight of sugar beet, so amount of this stream is considerable. Mixing of carbon black and water compose the colloid in liquid phase. These colloids do not separate easily. This water is black, thus it is unuseable. In this study used liming to refining of wastewater. Samples obtained from tow factories (sugar plant of torbat heydariyeh and joveyn). Lime was added into samples directly. Relationship of pH to amount of added liming, rate of deposition of carbon black, volume of mud and coagulation percent was investigated. the results shown that there is a strong correlation between amount of lime milk and given parameters and rate of deposition of carbon black, volume of mud and coagulation percent evaluate with obtained equations. Additionally the results shown that carbon black separate completely in pH=11.65, and obtain glassy water.

The tissue of fruit varies at different stages of growth and storage and by determining its characteristics, the stage of fruit maturity can be found. Depending on the type of tissue, the ultrasonic waves will attenuate and its speed will change too while crossing the fruit tissue. Thus, by calculating the attenuation coefficient value and its speed in no destructive way, the characteristics of fruit tissue and the rate of its maturity will be determined. In this study, peach fruits-the Tabrizi variety- were classified in ripen, semi-ripen, large and small groups and the validity of ripen and semi-ripen groups were confirmed by taste panel. Then, in addition to measuring the attenuation coefficient and velocity of ultrasonic wave parameters, the physic-chemical parameters of fruit, including dimensions, mass, density, hardness, reducing sugar, acidity, pH, dry weight and soluble solids contents, which are the maturity indices of peach, were measured and compared with ultrasonic parameters. Results showed that fruit size and degree of maturity significantly affect on the wave attenuation and wave velocity, respectively. The correlation coefficients between attenuation coefficient and hardness (without skin) in ripen and semi ripen groups were higher than 0.8 and also the correlation coefficients of attenuation coefficient in relation with the hardness (by skin) in ripen and semi ripen groups were higher than 0.7. Also, the correlations for both attenuation coefficient and wave velocity in relation with the pH were higher than 0.8 as well as correlation between wave velocity and acidity.