A Comparative Study between Microwave Hydrodiffusion and Gravity (MHG) and Ultrasound-Assisted Extraction (UAE): Chemical and Biological Characterization of Polyphenol-Enriched Extracts from Aglianico Grape Pomace

Abstract

The wine industry produces large amounts of grape pomace (GP), a waste that needs to be disposed of properly. Bioactive compounds with high added value can be recovered from GP as an interesting strategy to reduce the environmental impact. Here, two different technologies were employed to recover polyphenol compounds from GP: microwave hydrodiffusion and gravity (MHG) and ultrasound-assisted extraction (UAE). The further purification of UAE and MHG extracts was carried out through solid-phase extraction (SPE) to obtain three fractions, F1, F2 and F3. ATR-FTIR analysis confirmed the presence of sugar and polysaccharide components in F1, as well as non-anthocyanin and anthocyanin compounds in F2 and F3, respectively. Also, the chemical profile was determined by HPLC-UV-DAD, identifying the presence of catechin in F2, and malvidin-3-O-glucoside chloride and cyanidin chloride derivative as the main anthocyanin compounds in F3. The fractions and their parental extracts were characterized for total phenolic content (TPC) and scavenger activity by in vitro assays. We found that F2-MHG and F3-MHG contained phenol contents 6.5 and 8.5 times higher than those of the parental non-fractionated extracts. Finally, F3-MHG (100 μg/mL, w/v) was shown to reduce the proliferation of HT-29 cells.

Physico-Chemical and Microbiological Profile of Wine Lees of Red Wines from Local Grapes Varieties

“…It is considered to be the main byproduct of winemaking [7]. It represents a material with added value and is used in various industrial processes, including as an additive in food products, beneficially influencing the physico-chemical, functional and sensory parameters of new products [8]. Another waste from winemaking are grape seeds, which contain approximately 40% fiber, 10% -20% lipids, 10% protein, and the rest are sugars, polyphenolic compounds and minerals [8] [9].…”

“…It represents a material with added value and is used in various industrial processes, including as an additive in food products, beneficially influencing the physico-chemical, functional and sensory parameters of new products [8]. Another waste from winemaking are grape seeds, which contain approximately 40% fiber, 10% -20% lipids, 10% protein, and the rest are sugars, polyphenolic compounds and minerals [8] [9]. Residual yeast is another by-product that, according to European Regulation 491/2009 of 25 May 2009, represents the sediment that settles in winemaking tanks after fermentation, during storage, or after authorized treatment, or that is obtained after filtration or centrifugation of wine.…”