Journal of Food Biosciences and Technology
Year:2013 | Volume:3 | Issue:3|Papers Count:12

Aqueous enzymatic extraction of oil from pistacia khinjuk was performed using cellulase. The central composite design was used to optimize the parameters that are significant to the process. The influence of three regressors on the percentage of oil recovery from seed was evaluated using second-order polynomial multiple regression model. Analysis of variance showed a high coefficient of determination (R2) value of 0.99 indicating a satisfactory adjustment of the regression model to the experimental data. The positive sign for the coefficient of the interaction between pH and reaction time on the response indicated that a simultaneous increase in the pH and the reaction time led to an increase in oil recovery percentage. The optimum condition are as follows: temperature of 60oC, pH of 9, reaction time of 20 h and oil extraction recovery of 74.93%.

In this study, response surface methodology was used to optimize ultrasound osmotic pretreatment with finished freeze drying of black cherries. Freeze drying is a separation process based on the sublimation phenomenon. This process has the following advantages as compared to the conventional drying process, maintenance of the structure, moisture removal at low temperature (reduced transport rates), improved stability of the product during storage, and minimization of degradation reactions. The effects of osmotic pretreatments (with or without ultrasound) in combination with freeze drying and hot-air drying methods on black cherries were investigated. Osmotic pretreatments and dehydration were carried out in sucrose solutions of 40, 50 and 60% and temperatures of 40, 50 and 60oC respectively. The influence of ultrasound at 65 and 130 KHz on antioxidant properties was also investigated. The total anthocyanins of dehydrated black cherries at higher temperatures as well as sucrose were decreased while the total phenol increased. Ultrasound caused a reduction in the antioxidant activity of the samples that were subjected to the increased amount of anthocyanins degradation. Freeze drying modified total anthocyanins, total phenolic compounds and the antioxidant activity in the final product.

The history of food science, technology and nutrition and their expansion in respect of raw material, processing, finished products and nutritional value goes back to many years and is still the interests of many researchers. In this work ascorbic acid has been taken not only as an important and vital vitamin to be investigated during the course of different heat processes but also as an index to other vital and sensitive micronutrients. Titration by 2, 6 dichloroindophenol that only measures the ascorbic acid concentration was adopted as the mean to evaluate this reducing compound. The results indicated that microwave heating caused the highest loss during 20 minutes of heating as compared to other methods of heat treatments and this might be explained by the degree of heat, length of treatment, migration of ascorbic acid to the media and oxidation of ascorbic acid to de-hydro-ascorbic acid and other subsequent products.

The “Encyclopedia of Fermented Fresh Milk” has classified Acidophilus and Bifidus milks as Non-traditional fermented milk products. These products contain Lactobacillus acidophilus and Bifidobacterium spp., respectively, that are known as probiotic microorganisms. In this study, some aspects of acidity development, pH measurement and bacterial counts were monitored when these micro-organisms were grown in milk. The starter cultures of L. acidophilus La-5 and Bifidobacterium lactis Bb-12, obtained from Chr. Hansen in Denmark, were each inoculated at the rate of 0.01 g 100 ml-1 in UHT milk and incubated at 37oC for duration of 5 h (Acidophilus and Bifidus milks). The same procedure was carried out with the same inoculation rates of two mentioned starters as mixed culture (Acidobifidus milk). The titratable acidity measurements and pH values of the single strains fermented milks were similar, but the sour taste of Acido-bifidus milk of the mixed starter culture was more tangible when compared with the two other fermented products. From the limited data available, it was evident from the preliminary studies that the growth of B. lactis in mixed cultures was better as compared to the single strain, and it is suggested that a lower inoculum rate of starter cultures or shorter fermentation period might be recommended for the development of Acido-bifidus milk.

Large quantities of beef and mutton tallow are available in Iran every year. If these products are processed and formulated properly and scientifically, the need to import oils and fats in substantial quantities might be reduced. The aim of this study is to fractionate beef tallow into different fractions and carry out physical and chemical tests on each isolated fraction. Beef fat was obtained from butchery shop in Tehran. The fat or tallow was obtained by dry rendering using a rotary evaporator. Fractionation took placed at 4oC for 22 hours. Physical and chemical tests concerning melting point, colour, free fatty acid concentration, refractive index, peroxide value, iodine value, induction period measurement and fatty acid composition were carried out on the original and fractionated samples. The results indicated yields of 94% and 98% for extraction and fractionation respectively. The statistical analysis of the samples indicated significant differences between the results obtained. The results also showed that the liquid fraction might be employed as salad or frying oil and the hard fraction might be used as a fraction in margarine or shortening fats.

Using agricultural waste is one of the best ways to reduce the costs and the environmental pollution. Button mushroom´s stipe is a cheap by-product that is rich in nutrients for human nutrition. The purpose of this study is to compare the nutritional value of cap and stipe of button mushroom (Agaricus bisporus). The caps were separated from the stipes after harvesting and parameters such as moisture, protein, carbohydrates, fat, fiber, ash, minerals (potassium phosphorus, calcium, iron and selenium) and the fatty acid compositions were determined. Atomic absorption was employed to determine Iron, potassium and calcium and hydride generation atomic absorption spectrophotometry and gas chromatography were used to determine selenium and fatty acid composition of the product respectively. The result indicated that the caps on average contained 90.76% moisture and total solid content consisted of 33.65% protein, 20.59% carbohydrate, 2.48% fat, 33.11% fiber and 10.17% ash while the stipes contained 90.01% moisture where the solid content consisted of 19.01% protein, 31.41% carbohydrate, 2.00% fat, 38.08% fiber and 9.5% ash. The analysis of the extracted lipid revealed that the major unsaturated fatty acid was linoleic acid, while the predominant saturated fatty acid was Palmitic acid in both cap and stipe. According to statistical analysis, significant differences (p<0.05) were obtained between the chemical composition of caps and stipes. The results also indicated that the amount of calcium content in the stipe is twice higher than cap (2.08 g/kg) and the amount of iron and linoleic acid in the stipe is significantly higher than cap (p<0.05). The cap of the mushroom has significantly higher concentration of protein (p<0.05) than the stipes. From statistical point of view, button mushrooms stipe, contains higher quantities of fiber and carbohydrate in comparison with cap (p<0.05), that could have useful health promotion effects. Therefore, this valuable product that is often considered as an agricultural waste might be employed as a rich source of nutrients in food industries.

Ochratoxin a (OTA) continues to attract global attention concerning the hazard and impact on both human and animals based on its toxicity and occurrence. The International Agency for Research on Cancer (IARC) classifies it as possible carcinogen to human (group 2B). A total of 98 samples of dried fruits consisting of coconut, sour cherry, slices of peaches, quinces, and pineapple from Isfahan, Iran were analyzed for OTA by Enzyme linked immunosorbent assay (ELISA) technique. The mean recovery percentage of OTA in spiked dried fruit samples at the concentrations of 5, 10 and 20 ng/g were found to be 84.9, 89.3 and 90.4%, respectively. The detection limits for OTA by ELISA was 0.625 ng/g according to the manufacturer’s description. OTA was found in 3.1% of the analyzed samples by average concentration of 3.73 ± 2.27 ng/g. The incidence rates of OTA contamination in dried coconut, and slices of quince samples were, 10.0%, and 5.6%, respectively. The concentration of OTA in any of contaminated dried fruit samples were not higher than maximum tolerance limit accepted by the European Union (10 ng/g). This value reflects that the analyzed samples have a minimal contribution to toxicological risk.

Camel milk contains sufficient levels of insulin and does not form the coagulum in the stomach preventing degradation of insulin and act as an effective vehicle to take the milk insulin unchanged to the intestine. In present study direct spectroscopy and standard addition method, well-known methods in analytical chemistry were used for determining insulin concentration in camel milk. The concentration of insulin was determined by UV absorption measurement at wavelength of 276 nm. The linear range for calibration curve in direct spectroscopy was 2 to 8 units/liter insulin solution indicating good agreement with Beer-Lambert law. The camel milk was centrifuged and upper clear solution was separated. According to calibration curve, insulin concentration was determined by direct spectroscopy. In standard addition method, upper clear solution and sufficient amount of distilled water were mixed with insulin standard solution to prepare solutions for Uv-Vis spectroscopy. The insulin levels in upper clear solution were determined; 17.91± 0.40 and 18.65 ± 0.38 units/ liter, using standard addition method and direct spectroscopy, respectively. Both methods are capable of being used in determining insulin concentration in camel milk. However, it is suggested to use standard addition method for measuring insulin concentration due to decreasing matrix error during determination.

In this study the non-saponifiable matter of oils extracted from nine varieties of sunflower seed were subjected a series of chemical tests. The non-saponifiable matters were fractionated into a number of chemical classes of compounds namely sterols, 4 methyl sterols, triterpene alcohols, tocopherols and hydrocarbons. The two major and important classes of compounds consisting of sterols and tocopherols were evaluated qualitatively and quantitatively. The results indicated that a-tocopherol and b-sitosterol were the predominant tocopherol and sterol respectively. Zaria variety was evaluated as the superior variety in respect of tocopherol concentration and Lacumca variety in respect of sterol concentration.

Tea is one of the most popular beverages in the world and contains several important essential micro nutrients that are beneficial to human health. The contamination of tea leaves by heavy metals may pose serious problems to human health, because they are not biodegradable and remain in the environment and might enter the food chain. In this study, the concentration of heavy metals; Cd and Pb was measured by atomic absorption spectrometry (GFAAS) according to AOAC method of analysis. Ten samples of black tea cultivated in Iran were compared with 10 samples of imported black tea in 2011. The results of analysis showed that the mean level of Pb was 497.5 ± 175 ppb for Iranian and 293.3 ± 269.5 ppb for imported black tea. However, the value for Cd was 45 ±17ppb for Iranian and 9.14 ±7 ppb for imported black tea. The average contents of detectable heavy metals were significantly (P<0.05) higher in Iranian black tea. Cadmium and Lead concentrations in the sampled brands of black tea were lower in comparison with their upper limits (0.2 and 2 ppm for Cd and Pb, respectively), therefore, it might be concluded that there are not any health problems concerned with tea consumption, for these two elements.

The essential oil of plant material is the fraction isolated by means of several methods such as liquid carbon dioxide, microwaves and low or high pressure distillation employing boiling water or hot steam and is chemically defined as terpenoids namely monoterpene and the oxygenated form. Since these compounds might be employed as flavour contributors due to their chemical nature, it is the aim of this investigation to extract and identify the chemical compounds present in the essential oil of ginger. The essential oil of ginger was extracted and isolated by the application of Clevenger apparatus and the total phenolic compounds responsible for flavouring, preserving and antioxidant activities were determined. The results indicated that Zingiberene belonging to the sesquiterpene was the predominant compound present in the oily fraction. Therefore further investigation concerned with characterisation and applications for particular activities are recommended.

The commercial development of food products originated from the plants as sources of antioxidants to increase the health benefit and stabilize the food is of current interest. This study was aimed at obtaining dill extract using cold solvent method by three solvents, (methanol, acetone, and hexane) and examining the antioxidant potency and determining the oxidative stability of sunflower seed oil over storage time. Dill extracts were added to sunflower seed oil at 0.5, 0.3, 0.1, and 0.05% W/W concentrations. The antioxidant activities of the extracts were evaluated by measuring the peroxide value and the induction period employing Rancimat apparatus. The results showed that the sample containing methanolic extract of dill had the lowest peroxide value and the highest oxidative induction period or oxidative stability. The results also revealed that the antioxidant activity of the extracts is concentration dependent. Therefore, 0.5% methanolic extract of dill exhibited the greatest antioxidant activity and the stability was improved in sunflower seed oil. This study also indicated that the application of dill extract as a substitute to the current synthetic antioxidants in sunflower oil might be preferred.