Catechins and flavonol glycosides were extracted from green tea with methanol, ethanol and water. Crude extracts derived from green tea were then fractionated using ethyl acetate. After investigation of tea extracts, the following four catechins and three flavonol glycosides were well separated and determined with HPLC analysis i.e., (-)-epigallocatechingallate, (-)-epigallocatechin, (-)-epicatechingallate, (-)epicatechin, quercetin-3-rhamnosylglucoside, kaempferol-3-rhamnosylglucoside and quercetin-3-glucoside. The content of catechins and flavonol glycosides in green tea extracts varied from 4.27 to 65.46 and 0.06 to 1.66 mg g -1 dry weight tea, respectively, depending on the solvent used. Water was confirmed to be most effective solvent for extracting catechins and flavonol glycosides from green tea.
In this study, the effect of pretreatments (hot water blanching, microwave blanching and ohmic heating) on drying kinetics and quality characteristics of green bell pepper dried at 60, 70 and 80 °C was investigated. Four mathematical models were fitted to experimental data and Logarithmic model was found to be the best for all the samples. Rehydration ability of only ohmic heating pretreated peppers was higher than untreated ones. Total polyphenol (TP) content and antioxidant capacity (AC) of dried peppers varied between 3.21-5.08 mg gallic acid equivalent (GAE)/g dry matter (DM) and 1037.57–2407.40 mmol AAE/100 g DM, respectively. The content of ascorbic acid (AA) in dried samples was in the range of 187.25–722.55 µg/g DM. The bioaccessibility of TP after in-vitro digestion varied from 79.44 to 97.73%. Losses of chlorophyll a and b were very high in all samples compared to fresh ones but the most in control samples.
The purpose of this study was to optimize ohmic heating (OH) conditions using response surface methodology (RSM) for maximum recovery of polyphenols from industrial chestnut peel waste. Box-Behnken design (BBD) was applied to investigate the effects of three independent variables, namely electric field (V/cm), heating time (sec) and salt concentration (%). From RSM, optimum pretreatment conditions were obtained as 20 V/cm, 100 sec and salt concentration of 0.32%. Three chestnut peels were pretreated by these optimal conditions and their polyphenols were extracted using different solvents. Polyphenol contents and antioxidant capacities of peel extracts were dependent on the variety and extraction solvents used. HPLC analyses showed that ellagic acid was the most abundant phenolic compound in all varieties. OH pretreatment had a positive effect on extraction. Additionally, alcoholic extraction had a better recovery effect compared to water. The peel waste of Kiraz variety was found to be a good source for polyphenols.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.