جستجوی مقالات مرتبط با کلیدواژه "free radical scavenging" در نشریات گروه "صنایع غذایی"

Tea has a variety of fermented, non-fermentable and white tea.Tea contains compounds such as polyphenols, proteins, amino acids and organic acids.In this study, differences in the composition of black, green and white tea were investigated.Total phenols, flavonoid, flavonol, tannin, catechin, epigallocatechin gallate, caffeine, theaflavin, thearubigin, theaborunin, vitamin C, vitamin E contents, free radical scavenging and IC50 levels were measured.White and green tea had higher total phenols and tannin than black tea.The amount of flavonoid and flavonol (38.4 and 29.35 mg/g DW), catechin and epigallocatechin (96.81 and 65.41 mg/g) in white tea were higher than the other two types of tea.Black tea had higher caffeine content (5.25mg/g) than the other two types of tea.Theaflavin, thearubigine and theaborunin were found only in black tea. This showed that the phenolic compounds of black tea change as a result of fermentation.Green tea had the highest (13.39 µg/g) vitamin C and (33.18 µg/g) vitamin E.White and green tea were able to free radical scavenging at 36.89% and 56.87%, respectively. The amount of bioactive compounds present in the three types of tea is different and is related to its processing steps. However, all three forms of tea have compounds that have high antioxidant properties.

In the present study, the optimization process of phenolic compounds extraction and antioxidant activity (DPPH radical-scavenging assay, FRAP test, and oxidative stability index) of Pistacia khinjuk fruits was evaluated using ultrasound waves through response surface methodology (RSM). To optimize the extraction process from the central composite design with three independent variables including time (5, 27.5 and 50 minutes), temperature (25, 45 and 65 ° C) and ethanol ratio in water-ethanol solvent (0, 50 and 100% ) was used. Significant effects of independent variables on the extraction of phenol compound, DPPH radical scavenging power, FRAP test and OSI of P.khinjuk fruit extract, with the regression coefficients of 97.65, 98.09, 98.62 and 98.38 %, respectively, were noted. Among the independent parameters, ethanol concentration was the most effective parameter because two effects of quadratic and linear were observed in the proposed models of different tests. The interaction effect between different paprameters was not observed in the models of this study, too. It was also the strongest model for the phenolic compounds extraction test; because in this test, in addition to the linear effect of independent parameters that were common to all tests, a quadratic effect was also observed in the parameters of time and ethanol concentration. Also, the best antioxidant activity of P.khinjuk fruit was obtained by using the ultrasonic wave for 50 minutes at 65 ºC and with 57.7% v/v ethanol/water solution. Finally, it was found that the results of experimental tests were close to the values predicted by the response level method.

The objective of this study was to investigate the antioxidant and antimicrobial activities of the ethanol (EE), methanol (ME), and water (AE) extracts from the leaf of Pistacia atlantica subspecies mutica which naturally grown in Iran. The total phenol content and antioxidant activity of extracts were determined using spectrometric method according to the Folin–Ciocalteu phenol reagent and scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals. The extracts were evaluated for their antimicrobial activity against three Gram-positive, three Gram-negative bacteria and one yeast by assay for minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) using disc diffusion method. Results showed that the water extract had the highest total phenol content. But EC50 of water extract was 5.87 compared with BHT as synthetic antioxidant (3.94 mg/ml). The water extract with higher level phenolic compounds and scavenging DPPH showed the highest antioxidant and antibacterial effects, in comparison with the other extracts. It was found to be effective against all the test organisms with Gram positive strains being more sensitive than Gram negative strains. Also, the water extract were the most effective against the examined bacteria and yeast species, based on its higher content of phenolic compounds. Among the examined microorganisms, Streptococcus faecium and Candida albicans were found to be the most sensitive and resistant, respectively. According to finding of this study, water extract of Pistacia atlantica leaf could be used as a natural preservative in the food industry.