engleski

Influence of solvent polarity on total antioxidant capacity of high hydrostatic pressure extracted grape skins

High-pressure processing is novel technology that have the potential to enhance extraction yield of bioactive compounds. It could especially be useful as extraction technology from food waste, with minimal ecological impact, low power and solvent consumption. Investigation of high-pressure processing and solvent polarity on extraction yield of bioactive compounds from grape skins (without seeds) was conducted. Processing pressure parameters were optimized using the design of the experiment and set at 400 and 500 MPa during 6.5 and 10 min. Extraction was carried out using distilled water and ethanol (30 %, 50 %, and 70 %) as solvents, at room temperature. Total antioxidant capacity and FRAP of extracts were measured and statistically analyzed using ANOVA and posthoc tests. Obtained results show that rise in solvent concentration increases total antioxidant capacity and antioxidant power of extracts. This result is expected, however, the increase of polarity over 50 % did not increase total antioxidant capacity values of extracts, which are maximized at 400 MPa. TOAC also increased with an increase in time and pressure. Still, pressures over 400 MPa further increase TOAC for only 4 % at lowest solvent polarity and even decrease antioxidant capacity at higher solvent polarities. Pressures over 400 MPa could be considered as excessive and not necessary to maximize antioxidant capacity, especially as FRAP also had optimal value at 400 MPa. Comparison of results with water extracts not surprisingly show lower TOAC and FRAP values. However, maximal investigated high pressure and processing time significantly increased extraction yield. Using water, despite lower yields, could be viable cheaper, ecologically more acceptable and safer alternative to using organic solvents.

high pressure processing; food waste; grape skins; extraction

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