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INNOVATIVE COLD PLASMA-ASSISTED EXTRACTION FOR BIOACTIVE COMPOUNDS FROM AGRICULTURAL BYPRODUCTS
Fruits play a necessary role in the human diet, and their cultivation is important to the prosperity of any country worldwide. However, fruit waste generated in large quantities in agricultural value chain is normally used to feed animals or directly disposed to landfill, ending up with low economic value and a heavy environmental burden. Agricultural waste that contains significant amounts of bioactive compounds can be utilized as byproducts and valorized through bioactives recovery. Conventional bioactive compounds extraction includes intensive uses of organic solvents and also has relatively low efficiency. Therefore, an environment-friendly alternative with higher extraction efficiency is needed. Cold plasma can convert gaseous medium to a highly reacting state with low energy cost, generating reactive species that are able to disrupt cell structures as well as modify material surfaces. This study has developed an innovative cold plasma-assisted extraction technology to enhance the recovery of bioactive compounds from fruit processing byproducts. The objectives of this study are to examine the effects of dielectric barrier discharge plasma on fruit pomaces, in terms of (i) surface microstructure and properties, (ii) extraction efficiency of their bioactive compounds, and (iii) bioactives composition and nutritional value of their extracts.
High voltage atmospheric cold plasmas (HVACP) generated with different working gases (air, argon, helium and nitrogen) were applied on tomato pomace (TP). In addition to creating ruptures on TP epidermal cells, HVACP treatments were found to decrease the water contact angles of tomato peels and accelerate the drying of tomato fruits, indicating the formation of more hydrophilic surfaces. Helium and nitrogen plasmas-treated TP showed increased PC extraction yields by 10%, and all HVACP-treated samples exhibited higher AA and changes in their phenolic compositions.
Grape pomace (GP) from red wine production was treated by helium-HVACP for different time periods (5, 10 and 15 min). Similar cell structure disruption and surface hydrophilicity enhancement were observed, and the effects became more significant as treatment extended. HVACP treatment also increased the total phenolic content in GP extracts, by 10.9−22.8%, which contained a higher anthocyanin concentration and showed an improved AA (16.7−34.7%). Furthermore, competitive effects of HVACP treatment on PC extractability enhancement and their degradation were observed.
The results of this study have proved that HVACP-assisted extraction successfully improved the extraction efficiency of bioactive compounds from fruit pomace and enhanced the nutritional quality of their extracts. This novel technology is a promising method for valorizing different agriculture byproducts into functional food ingredients and nutraceuticals with high nutritional values, which thus can bring significant economic benefits to the agricultural, food and nutraceutical industries.