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This study was performed to investigate the enhanced antioxidant effects of citrus pomace (CP) extracts processed by super-heated steam (SHS). CP extracts were obtained using a closed SHS system at three different temperatures (100, 200, and 300 °C) with an extraction time of 10 or 20 min. These extracts were evaluated for their antioxidant activities by measuring their DPPH, alkyl, and hydroxyl radical scavenging activity using Electron Spin Resonance (ESR) spectroscopy and for their protective effects against H 2 O 2 -induced oxidative stress in Vero cells. All extracts exhibited strong radical scavenging activities and protective effects against H 2 O 2 -induced Vero cell damage. Especially, the SHS-CP extracts obtained at 300 °C with extraction times of both 10 min and 20 min exhibited antioxidant activities that were significantly higher than those of ethanol extracts and SHS-CP extracts obtained at other temperatures. The total phenolic and flavonoid contents of SHS-CP extracts and their antioxidant activities were found to be increased with elevated processing temperatures. Moreover, gas chromatography/mass spectrometry (GC/MS) in the presence of a methylating reagent revealed that some characteristic polyphenols and polyhydroxycyclohexanes were present in the SHS-CP extracts. Thus, this study demonstrated that SHS extraction is an efficient and environmentally friendly method for extracting antioxidants from CP. [ABSTRACT FROM AUTHOR]

The presence of phenolic compounds, possessing outstanding antioxidant activity corresponding to ascorbic acid, in wasted acorn shells was revealed by means of thermochemolysis-gas chromatography/mass spectrometry (thermochemolysis-GC/MS) in the presence of organic alkalis. The chromatogram of intact acorn shell samples obtained by thermochemolysis-GC/MS using tetramethylammonium hydroxide (TMAH) showed a strong peak of 3,4,5-trimethoxybenzoic acid methyl ester. This product was also clearly observed on the chromatograms of the methanol and water extracts from the acorn shells, indicating that 3,4,5-trimethoxybenzoic acid methyl ester was derived from free and/or esterified gallic acids through the thermochemolysis reaction. Based on the peak intensities, the contents of gallic acid components were determined as ca. 27 wt% for the both extracts. Furthermore, the content of free gallic acid was selectively estimated with discriminating from its esterified counterpart by using tetramethylammonium acetate (TMAAc) as a methylating reagent. These results were also correlated with high antioxidant activity of the acorn shell extracts evaluated by a DPPH radical scavenging method. [ABSTRACT FROM AUTHOR]