Journal of Food Biosciences and Technology
Volume:5 Issue: 1, Winter-Spring 2015

Extraction of oil from poor quality pistachios results in increased add-value. In this study, the performance of different solvents in recovery of valuable oil and meal from the pistachio sample contaminated with aflatoxin was investigated and some chemical properties of the extracted oil were determined. The pistachio nut oil was extracted by three solvent systems including n-hexane (non- polar), ethanol 96˚ (polar) and n-hexane- ethanol 96˚ (90:10) using soxhlet method and for each solvent the mean yield was determined. Fatty acid profile, Iodine, peroxide and acid values of the extracted oil were determined. Aflatoxin contents in the produced oil and meal were measured. Extraction yield of the pistachio oil by different solvents ranged from 33.6% in the samples extracted by ethanol to 40.4% in the sample extracted by n-hexane-ethanol (90:10). The most predominant saturated and unsaturated fatty acids found in the pistachio oils were palmitic and oleic acids, respectively. The highest amount of aflatoxin was found in the oil extracted by ethanol and in the meal recovered by n- hexane.

One of the most important forms of preharvest damage to wheat is caused by sunn pests. The insects insert their mouth parts into the immature grain and while injecting their saliva suck the milky juices. Flour from damaged wheat results in low baking performance due to the bug proteolytic enzymes’ injected which cause the breakdown of gluten structure in the dough. In the present study three wheat varieties named Alvand, Mahdavi and Roshan with different levels of bug damage were studied. The effect of bug damage on physicochmical properties showed reduced thousand kernel weight, protein and ash contents. Gluten and gluten index decreased significantly upon bug damage. Among the factors the degree of gluten hydrolysis, total reducing substances and sulfhydryl groups content were increased upon bug damage in all the three varieties examined but disulfide groups content was reduced. Monitoring of the wheat flour protein by SDS-PAGE indicated that some of the bands related to HMW-GS at the top of electropherogram were disappeared and the intensity of some other were decreased. In Roshan and Alvand varieties, the intensity of bands with similar mobility to gliadins was decreased. Incubation of bug-damaged samples resulted in further degradation of electropherogram bands of high molecular weights and development of bands with lower molecular weights that is due to the hydrolyzing effect of bug protease.

Preliminary investigation on antioxidative potentials of defatted fermented locust bean extract in comparison to defatted non-fermented locust bean was conducted. Qualitative antioxidative assessment on the extract was accomplished by screening the phytochemical endowment, and similar bioactive components. Also some antioxidative indices were quantitatively evaluated. Results showed that the defatted fermented samples were characterized with high amount of phytochemical and bioactive compounds notably phenolic compounds, saponins, peptides, amino acid and reductones. However, alkaloids and flavonoids were not detected. UV-Spectral characteristics of the extracts corroborated same. Similarly, quantitative antioxidative markers evaluated showed that the antioxidative capacity in terms of relative reducing power, total phenolic content and DPPH of fermented locust bean of defatted fermented locust bean extract were higher than the antioxidative capacity of the corresponding   defatted non-fermented locust bean extract.  Also, the antioxidant activity rate content, and EC50 of the extract were evaluated. This study demonstrated the antioxidant endowment of fermented locust bean condiment in comparison to non-fermented locust bean condiment.

Essential oils are commonly used to treat minor health problems. In this study the chemical compositions of Lavandula officinalis and Thymus vulgaris were determined by gas chromatography and mass spectrometry. GC/MS analysis of T. vulgaris resulted in thymol as the major oil component where as methyl sulfony exhibited as the most abundant constituent of L. officinalis. The antibacterial activities of these essential oils (Eos) against Five gram negative bacteria, namely Pseudomonas aeruginosa, Salmonella paratyphi (D), Citrobacter, Enterobacter, Escherichia coli and gram positive bacteria Staphylococcus aureus coagulase were investigated. Among the tested plants, Thymus vulgaris showed higher activity against different bacteria, while S.paratyphi and S. aureus were the most resistance bacteria. All the tested plant extracts possessed antimicrobial growth activities with MIC values ranging from 100 to 150µL/mL. The results suggested that due to the potential antimicrobial activities of these essential oils they might be employed in food and pharmaceutical products.

The objectives of this paper were production of probiotic yoghurt using L. paracasei ssp. tolerans, and evaluation of pH changes, viable counts, and organoleptic properties of the produced yoghurt. It was observed that the pH decrease during the fermentation period was faster in the milk inoculated with L. paracasei ssp. tolerans plus starter culture. There was a gradual decrease in pH in both of the fermented milks during the first 120 min, followed by a sharp drop between 180-210 min, and a steady reduction later until the desired pH was achieved. The viable count of the probiotic bacterium (L. paracasei) decreased almost linearly during the storage time, but remained higher than the standard limit for probiotic products. Incorporation of L. paracasei ssp. tolerans in yoghurt neither affected the viability of the starter cultures during 21 days of cold storage, nor the organoleptic properties of the yoghurt. There was no significant difference between organoleptic properties of the control and the probiotic yoghurts.

Oil in water emulsions have attracted considerable attention in food industry due to their large applications. In this study, the effect of thermal treatment on oil in water emulsions (o/w) containing 40% oil was studied. The emulsions were prepared using xanthan gum, guar gum and carboxymethyl cellulose as stabilizer and polyoxyethylen sorbitan monooleat as emulsifier. A mixture design was used to define the percentage of each stabilizer to simulate wide range of emulsions. The emulsions were pasteurized at 87 ºC for 15 minutes. Thermal treatment had a considerable influence on rheological properties of the emulsions. Viscosity of all emulsions decreased after thermal treatment and stabilizers had increasing effect on this response. All emulsionsexhibited non Newtonianpseudo plastic flow behaviorthat often referred to as shear thinning (n<1). A non linear relation between shear rate and shear stress was observed. Shear stress versus shear rate data was successfully fitted to the Power-law model. Consistency coefficient (K) decreased and flow behavior index (n) increased after thermal processing. Thermal treatment caused an increase in particle size of emulsions because of coalescence. Some of emulsions had heterogeneous coalescence (bimodal) and some of them had homogenous coalescence (mono modal). All emulsions were stable to centrifugation and did not breakdown. It was found that surface tension was affected more by temperature than by stabilizer content. Surface tension decreased by thermal processing. Viscosity of all the samples was reduced during storage. The results showed that developed emulsions are thermally under pasteurization temperatures.

The oxidative stability of margarine supplemented with different concentrations of fennel (Foeniculum vulgare) seed extract (FSE) was compared to the synthetic antioxidants; butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) at legal concentrations. The experiment was carried out under accelerated storage conditions for 4 weeks employing peroxide value (PV), p-anisidine value (AV) and TOTOX value at constant time intervals of 7 days. The induction period measuring the stability of the oil was determined by Metrohm Rancimat. The extraction yield from fennel seeds was 12.92% w/w. It was concluded that the antioxidant effeciency of the extract was concentration dependent and by increasing the concentration from 80 to 100 mg kg-1, the antioxidant activity of the extract was increased. After 4 weeks of storage at 90°C, margarine containing 100 mgkg-1 FSE showed lower peroxide values, p-anisidine values and TOTOX values and higher induction periods as compared to the synthetic antioxidants, BHA, BHT and the control. These results illustrate that FSE might be used as a potential source of natural antioxidant to retard lipid oxidation in margarine.

In this study, modified starch was used as a fat replacer in the milk. The fat replacer was manufactured from modified starch such as pre-gelatinized and cross–linked starches. Modified starches were manufactured by hydrochloric acid and citric acid treatments from potato and wheat and were added to skim milk at concentrations of 0.15%, 0.30% and 0.45%. Viscosity, total solid, fat content, titrable acidity, pH and sensory scores were evaluated for the prepared milk samples. The plant source and kind of modification affected the physicochemical and sensory properties of the milk sample significantly. The impact of modified starch concentration and kind of acid used for modification on sensory property and viscosity of the milk samples was significant. The results indicated that pre-gelatinized starch at the concentration of 0.45% and cross-linked starch at concentration of 0.3% might be selected for the addition to skim milk but milk sample with cross-linked starch was superior due to its acceptable texture and flavor.

In this project, different nettle plants from north regions of Iran including Tonekabon, Amol and Gorgan were collected. The oil was extracted using soxhlet extraction apparatus and was subjected to series of physical and chemical tests and determinations consisting of refractive index, melting point, smoke point, nonsaponifiable matter, Iodine value, saponification value, peroxide value, totox value, acid values, kreis test and fatty acids composition. Among the samples collected the one obtained from Gorgan had the highest oil content. Fatty acid analysis of the extracted oils indicated a high degree of unsaturation where linolenic acid accounted for 28.7 % of the total fatty acids with an unusual concentration of C17:0. The oil also showed a high concentration of nonsaponifiable matter where the sterol constituted the major part of this fraction.

Hydrogenation of oils might be considered as the largest reaction in the edible oil industry. The reaction consists of the addition of hydrogen at the double bounds of fatty acids. Although for some reasons this might be considered a desirable reaction but for some others it might create problems in the food and nutrition chain circle due to the formation of saturated and trans fatty acids. Soyabean oil was selected and hydrogenated and physical and chemical properties consisting of acid value, percent free fatty acid, peroxide value, color, Iodine value, induction period, saponification value, percent non saponifiable matter and fatty acid composition were determined and evaluated before and after hydrogenation process. Hydrogenation process has caused reductions in color, Iodine value, unsaturation with increased formation of some trans fatty acids.