The effect of processing of pomegranate juice on antioxidant activity and its relationship with total phenols

The antioxidant activity of pomegranate juices extracted by two methods was determined using three methods: β- carotene, Linoleic acid emulsion, and DiPhenel Picryl Hydrazyl (DPPH). The juice was extracted by separation arils from fruits and squeezed using Cyclone machine (T-1), while the second extraction method included squeezing the whole halve fruit with previous machine, (T-2). The potential compounds were determined using ethanol in a comparison with Butylated hydroxyl Anisole (BHA) as reference antioxidant. There were significant differences (P<0.05) in the antioxidant activity between the treatments in all measuring methods. The means of antioxidant activity amounted to 82.66% in T-1, 86.82% in T-2 and 86.98% in BHA. There was significant relationship between total phenols and antioxidant activity in all treatments.

The impact of processing the strawberry jam on indices of some chemicals and biologically active compounds

The research was carried out in the laboratories of food science department at Faculty of Agriculture, Damascus University during the year 2012 to compare some chemical parameters (moisture،ash, sugars, fat, fibe, protein) and biological active compounds (total phenols, vitamin C) in fresh strawberry fruits and strawberry jam. Statistical analysis showed a significant reduction (p<0.05) in moisture, ash, fat and protein in strawperry jam comparing to fresh fruits. Total phenols was decreased significantly (P< 0.05) from 2078 mg/100 g DM in fresh strawberries to 1070 and 962 mg /100 g DM in homemade and commercial strawberry jam respectively. Also the amount of vitamine c was decreased from 346 mg /100 gram dry matter in fresh fruits to 45 mg/100 gram dry matter in locall made jam ،while it was 30 mg/ 100 gram dry matter in commercial strawberry jam. These were reflected on anthocyanins which was decreased from 1080 mg/ 100 g DM during processing to 132 and 105 mg/ 100 g DM in homemade jam and commercial strawberry jam respectively. These changes reflected in a significant (P< 0.05) decline in the antioxidant activity.

The effect of sulphur dioxide (SO2) and drying methods in chemical and bioactive indicators and antioxidant activity in local yellowish Baladi grape

This study was carried out in the laboratories of the Faculty of Agriculture, Damascus University in 2012 season. Clusters of local yellowish baladi grape exposed to the concentration (2000 Ppm) of gas SO2 for 3 hours were dried to moisture content not exceeded 18% by different drying methods (sun drying, heat drying, solar energy-green house) in the aim of determining their effect on some chemical indices (total sugar, pH, acidity, solid soluble, non enzymatic browning), some antioxidants (vitamin C, total phenols) and antioxidant activity according to 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The results showed superiority (p<0.05) of the way solar drying of the fruits of the grape-treatment with gas SO2 to maintain vitamin C (7.17 mg/ 100 g dry weight) while outperformed the fruits of grapes dried with heat treatment and gas SO2 in content of phenols (7.24 mg acid Gaelic/ 100 g dry weight). Results also showed that samples of grapes dried solar and non-treated with gas SO2 noticeable increase in its activity in the antioxidant, which amounted to 82.42%. The results confirmed that the importance of treatment with gas SO2 prior to the fruits of grapes in reducing (p<0.05) the time required to complete the drying process, especially in the way of thermal drying to (137 hours) compared with other transactions.

Biological active compounds and antioxidant activity of main Syrian orange cultivars

The main properties(yield of juice, total soluble solid, pH, total acidity, total sugars), some antioxisant compounds as (vitamin C, carotenoids, total phenol, anthocyanins), and antioxidant activity measured by DPPH method for some main Syrian orange cultivars (navel, valancia, blood orange, and shamouti) were investigated. The results showed that valancia was the highest in juice yield (55.16%), while navel had the highest content of carotenoids(8.68mg/100g) and the lowest one of vitamin C(31.53mg/100g). Whereas, blood orange was superior in its content of total phenolic (295.73 mg gallic acid100/g) and antioxidant activity, (74.833%) among the studied cultivars.

Evaluation of Antioxidant Activity of Some Natural Extracts and Propyl Gallate in Refined Palm Oil

Some local natural sources of antioxidant such as orange peel extract (Citrus sinensis), pomegranate peel extract (Punica granatum) and ginger extract (Zingiber officinale L.) were evaluated during 5 days storage of refined palm oil at 63°C as compared to the synthetic antioxidant such as propyl gallate. The above extracts were obtained with ethanol and oil (palm oil). Those extracts were added to the oil at two different levels (100 ppm and 200 ppm). Antioxidant activity of natural extracts, synthetic antioxidant and the control treatment without antioxidant under thermal treatment (Schaal test) was assessed by measuring acid value (AV), peroxide value (PV), iodine value (IV) and refractive index (RI) during 6 days storage of refined palm oil at temperature mentioned above. Antioxidant activity also measured by studying the stability of oil by the use of rancimat method. All treatments exhibited antioxidant activity. Statistical analysis results were shown that the pomegranate peel extract treatment was significantly (P<0.05) superior than the orange peel extract and ginger extract treatments whereas, it was not significant difference about propyl gallate treatment.

Extraction of phenolic compounds from (Hops,grape seeds ) and study its antioxidant activity

The phenolic compounds were extracted from leaves and flowers of Hops and grape seeds from local production by soaking with different solvents (Methanol-ethanol-alcohol and water mixture) . The polyphenols content in the methanol extracts for 100 g dry matter was 6.31 g for the grape seeds, 2.08 g for Hops leaves and 0.6 g for Hops flowers. Methanol extracts were characterized by an antioxidant activity that appeared by their ability to Reduce ions ferriques Fe+3, at a concentration of 2500 ppm, the Reducing Power was 96.45% , 67.56% for the grape seeds and Hops leaves, respectively. The methanolic extracts of grape seeds and Hops leaves at 80 ppm showed activity in scavenge free radical DPPH. was 82.04% and 40.92% respectively. The methanolic extracts of grape seeds and Hops leaves at 250 ppm gave the ability to protect linoleic acid from the oxidation process of 78.98% and 48.41%, respectively. The antioxidant activity values of the extracts were compared with standard samples of ascorbic acid and BHT.