Proceedings of International Congress on Bioactive Compounds and International Workshop on Bioactive Compounds
Proceedings of 2nd International Congress on Bioactive Compounds and 3rd International Workshop on Bioactive Compounds

The growing demand for healthy products that generate less impact on natural resources has driven the development of new ingredients and processes. The use of green technologies and solvents to obtain natural compounds from agro-industrial waste is an alternative to a circular economy capable of containing the advance of environmental changes, promoting better use of plant matrices, reducing waste disposal, and generating products of high added value. Each country focuses typically on waste from its local agro-industry; however, Brazil has immense and diversified agro-industrial production with different residues that can be exploited in each region, as is the case for grape pomace (GP) in the southern region of Brazil. GP is the main solid residue generated during the industrial processing of grapes and is composed mainly of skin and seeds, representing approximately 30% of the total mass of the fruit. Therefore, this study aimed to evaluate the recovery of anthocyanins, sugars, and organic acids from black grape pomace ('BRS Vitória') through a new automated system (PHWE/SubCWH-SPE × HPLC-PDA/RI) based on the coupling of pressurized hot water extraction (PHWE) and sequential subcritical water hydrolysis (SubCWH) with in-line purification by solid phase extraction (SPE) and on-line analysis by high-performance liquid chromatography (HPLC) using photodiode array (PDA) and refractive index (RI) detectors. A sample of 5 g of GP was loaded into the extraction cell, and the SPE column was packed with PoraPak™ Rxn adsorbent. The adsorbent was activated through bypass with 30 mL of ethanol and conditioning with 30 mL of water at 2 mL min-1. Next, PHWE was performed at 60 °C, 10 MPa, and 2 mL min-1 of ultrapure water (pH 2.0) acidified with phosphoric acid for 30 min. After extraction, adsorbent desorption was started using the bypass and applying 0.25 mL min-1 of 50% ethanol (v v-1) as eluent for 60 min. After desorption, SubCWH was performed at 180 °C, 15 MPa, and 5 mL min-1 of ultrapure water for 60 min. Twelve peaks of anthocyanin compounds were identified, and the extraction yield obtained by HPWE was 47.60 ± 0.69 milligrams of cyanidin-3-glycoside equivalent per gram of dried black grape pomace (mgC3G gDBGP-1). Through SubCWH, 6 organic acids (citric acid, succinic acid, lactic acid, acetic acid, propionic acid, and isobutyric acid) and 5 sugars (cellobiose, glucose, mannose, fructose, and arabinose) were identified and quantified. Lactic acid represented 43% of the total organic acids and mannose 52% of the total sugars. Therefore, the newly developed method proved viable for performing HPWE and SubCWH of GP with SPE purification and on-line HPLC analysis of different classes of natural compounds. In this way, GP can be applied in the manufacture of various products, food, cosmetics, and drugs, adding antioxidant elements and bioactive compounds that can help improve the quality of life and the nutritional quality of food.