Influence of Tea Brewing Parameters on the Antioxidant Potential of Infusions and Extracts Depending on the Degree of Processing of the Leaves of Camellia sinensis.

The polyphenol content of tea depends on the growing region, harvest date, the production process used, and the brewing parameters. In this study, research was undertaken that included an analysis of the influence of the brewing process parameters on the content of total polyphenols (Folin-Ciocalteu), epigallocatechin gallate (HPLC), and antioxidant activity (against DPPH radicals) of fresh tea shrub leaves grown from Taiwan and of teas obtained from them (oolong, green in bags, and green loose from the spring and autumn harvest). The antioxidant potential was determined in the methanol and aqueous extracts, as well as in infusions that were obtained by using water at 65 or 100 °C and infusing the tea for 5 or 10 min. The highest content of total polyphenols and epigallocatechin gallate was found in green tea extracts from the spring harvest. However, in the case of infusions, the highest content of these compounds was found in green tea in bags. Steaming at 100 °C for 10 min, turned out to be the most favourable condition for the extraction. Oolong tea, brewed at 100 °C for 5 min was characterised by the highest antioxidant activity against stable DPPH radicals.

Quality assessment of cold-pressed strawberry, raspberry and blackberry seed oils intended for cosmetic purposes.

BACKGROUND: Cold-pressed berry seed oils are used for consumption and other applications including skin and hair care. They are natural products which gain the attention of customers. In this study, strawberry, raspberry and blackberry seed oils used for cosmetic purposes, purchased from three different European producers, were analyzed. The aim of the study was to assess the quality and oxidative stability of the berry fruit oils, thus they were analyzed after purchase and after 4 and 8 weeks of storage at room temperature. METHODS: Acid and peroxide values were determined in the tested oils, as was oxidative stability, which was measured using pressure differential scanning calorimetry (PDSC). Additionally, fatty acid profiles and thei. RESULTS: nd. Cold-pressed berry seed oils are used for consumption and other applications including skin and hair care. They are natural products which gain the attention of customers. In this study, strawberry, raspberry and blackberry seed oils used for cosmetic purposes, purchased from three different European producers, were analyzed. The aim of the study was to assess the quality and oxidative stability of the berry fruit oils, thus they were analyzed after purchase and after 4 and 8 weeks of storage at room temperature. Materials and methods. Acid and peroxide values were determined in the tested oils, as was oxidative stability, which was measured using pressure differential scanning calorimetry (PDSC). Additionally, fatty acid profiles and their distribution at sn-1,3 and sn-2 positions of triacylglycerols were characterized. Results, principal. Most of the fatty acids of the tested berry seed oils are polyunsaturated fatty acids (67.04-74.95%). The results show the low quality of the tested oils in terms of oxidative stability (high peroxide values: 21.9-249.6 mEq O2/kg oil). CONCLUSIONS: Based on this study, it is necessary to evaluate the effects of these products on the body. Moreover, standards clarifying the oxidation of cosmetic oils should be set internationally.