نشریه پژوهش های علوم و صنایع غذایی ایران
سال پانزدهم شماره 6 (پیاپی 60، بهمن و اسفند 1398)

In order to inhibit the oxidation of lipids, improve the oxidative stability of foods and to minimize the hazard risk to human health, antioxidants are added to food materials in industrial processing. In this work, the antioxidant potential of cinnamon (Cinnamomum zeylanicum), ajowan (Carum copticum) and zataria (Zataria multiflora Boiss.) essential oils (EOs) at different concentrations (0, 1 and 1.5%) on free fatty acid content (FFA), peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) of grape seed oil stored at 60ºC was evaluated. Ajowan treated samples (1.5%) showed the lowest (1.02%) and zataria treated samples (1%) expressed the highest (1.19%) FFA value among EO-treated samples. Samples treated with 1.5% cinnamon showed the lowest PV (69.5 meq O2/ kg) at the end of the storage period. Following control, the highest PV was seen in samples treated with zataria (1%). Grape seed oil samples treated with 1 and 1.5% cinnamon showed the lowest TBARS values during the whole storage period (one month). TBARS of zataria treated samples increased slightly toward the end of storage and a similar trend in TBARS was observed for samples treated with ajowan. The antioxidant activity of EOs in grape seed oil followed in descending order was cinnamon, ajowan, and zataria.

Ultrasound assisted extraction (UAE) has attracted growing interest, due to its great advantages for the extraction of bioactive compounds from plant species. Ultrasound efficiency is affected by various factors such as extraction temperature, extraction time, intensity of ultrasound waves, and type of ultrasound system. Therefore, this study aimed to investigate the process conditions of two ultrasonic systems (bath and probe) to determine the highest extraction efficiency of phenolic and flavonoid compounds in oregano leaves and the best ultrasound extraction conditions. The effects of different combinations of the ultrasonic variables include bath (40-60 °C; 30-60 minutes) and probe (40-60°C; 5-25 minutes and ultrasound amplitude: 20- 40%) were studied using ethanol-water (50:50v/v) solvent. The antioxidant activities of the extracts were then evaluated by the 2, 2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and reducing power tests.The best conditions for extraction of phenolic compounds and flavonoids were obtained using ultrasonic probe system at 50 ° C for 15 minutes and amplitude of 40%. The maximum total phenol and flavonoid were 473.22 ± 25.9 μg of gallic acid equivalent and 46± 1.24 μg of quercetin equivalent per mg of dry extract, respectively. The results showed that the UAE method had a considerable effect on the extraction of bioactive compounds from oregano leaves, and also the probe system had a higher efficiency than the bath system.

A nutraceutical food may provide expanded utility beyond its nutritional benefit. These benefits are commonly attributed to the active components of the food. Fruit by-products are rich source of dietary fibers that have beneficial effects on human health. Also they can improve the growth and viability of probiotics in food matrix and therefore suitable to produce synbiotic food products. In this study, the effect of adding fiber obtained from apple, banana and mango peels at levels of 0.5, 1 and 1.5% on physicochemical and sensory features and the viability of Lactobacillus casei LC-01 in ice cream during 60 days storage at -18°C was investigated. Based on the results, all ice cream mixes were pseudoplastic fluids. The values of flow behavior index decreased and consistency coefficients increased by increasing the level of all mentioned fibers. The pH and specific gravity of samples containing banana and mango fibers were lower than control and sample with apple fiber. Using fibers had no significant effects on overrun values, whereas viscosity and melting resistance of ice cream samples increased with increasing fiber amounts. The most reduction in Lactobacillus casei LC-01 count after freezing and during storage period was associated to control sample and adding all types of examined fibers improved probiotic viability. Minimum cell reduction after freezing and during storage period occurred in sample containing 1.5% mango fiber with 0.03 and 0.48 log cycle respectively. Sensory properties of samples containing apple fiber were good and comparable with control sample.

This study evaluated the effect of different dynamic and static loadings and different storage periods on the firmness of pear fruit. Pear fruit was first segregated into three groups of 27 pear in order to undergo three loadings: static thin-edge compression loading, static wide-edge compression loading and dynamic loading. All loaded pears were stored in accordance with three storage period designs: 5-day storage, 10-day storage, and 15-day storage. Following each period, the variations of pear texture were scanned by using the CT-Scan technique as a non-destructive test. Then, the firmness of pear texture was measured using a penetrometer. Data were simulated and evaluated using MLP and RBF artificial neural networks. The results showed that with increasing storage time and loading force , the firmness significantly decreased (1% level) in all three types of loading, In addition, pear texture was destructed under dynamic compression loading in order to compare with other two loadings. Best value artificial neural network for wide edge loading (12 neuron-RBF) was (R2 Wide edge= 0.9738– RMSE Wide edge=0.3419- MAE Wide edge =0.268) and for thin edge loading (4 neuron-RBF) was (R2Thin edge = 0.9946– RMSE Thin edge =0.170977- MAE Thin edge =0.133), also for dynamic loading (8 neuron-RBF) was (R2 Dynamic loading = 0.9933– RMSE Dynamic loading =0.230- MAE Dynamic loading= 0.187).

Central composite design response surface methodology was used to optimize polysaccharide extraction from olive leaves. Effect of three independent variables [extraction time (3- 7 hours), extraction temperature (60- 100°C) and water-to-raw material ratio (5-25 mL/g)] on extraction yield were studied. Extracted polysaccharide was evaluated for antioxidant properties, total phenolic and flavonoid content and its structure and functional groups were studied using FTIR. Rheological properties and flow behavior of polysaccharide were determined by fitting to power law model. The most important parameter in experimental ranges was temperature and the lowest effect was seen in extraction time. Highest extraction yield was obtained at extraction time of 2 hours, extraction temperature of 80.96°C and water-to-raw material ratio of 17.94 mL/g. Antioxidant properties of extracted polysaccharide were measured using DPPH radical at 517 nm that showed notable antioxidant properties. Rheological property of extracted polysaccharide was studied at 1, 2.5 and 5% concentration. Results showed that at high concentration, polysaccharide shows shear thinning behavior. One of the most important obstacles in native polysaccharide applications is their extraction yield. Extract of olive leaf polysaccharide is highly affected by extraction temperature. Extracted polysaccharide showed good antioxidant properties comparing to BHT and phenolic extract of olive leaf. Moreover it could be used for increasing solution viscosity at higher concentrations.

Discerning the expiration status (non-rejected and rejected) of edible vegetable oils is very significant because of the hazardous primary and secondary oxidation products. Therefore, it is of outmost importance to monitor the quality and safety of these oils. Based on previous literature, reports and experimental observation, the oil color changes during oxidation. Thus, the present study investigates the use of image processing and linear discriminant analysis (LDA) for the classification of non-rejected and rejected edible vegetable oils during oxidation process at 85°C, with respect to the induced period in both primary and secondary oxidation of four oil type (Olive, Sunflower, Palm and Soybean). The purpose of this study was to find less costly and quicker methods with environmental protection, by using the color spaces (RGB, HSI, L*a*b* with Grayscale) instead of chemical analyses to determine the expiration status of edible vegetable oils. Results of this study indicated that the best classification for expiration status of known oils according to induced period of peroxide value in  each color space, was achieved with LDA model were for palm with 100% (HSI and Grayscale), olive with 84.61% (L*a*b* and RGB), soybean with 95% (Grayscale) and sunflower with 100% (RGB and HSI), also in induced period of carbonyl value test, the best classification performance was achieved in palm with 100% (L*a*b*), olive with 100% (L*a*b*), soybean with 89.47% and sunflower with 95% (HSI).