Optimization of the extraction procedure of polyphenols from red Pinot Noir grape seeds

Department of Biotechnology, “Prof. Dr Assen Zlatarov” University, Burgas, Bulgaria

^* Corresponding author: qvor_burgas@abv.bg

Abstract

Grape seed extract (GSE) in the last years is commercialized as a valuable ingredient in the food industry. The aims of this study are to optimize the extraction procedure of polyphenols from seeds of red Pinot Noir grape and to evaluate the phenolic content, antioxidant and antimicrobial potential of the obtained extract. Two conventional methods (with shaker and magnetic stirrer) and two non-conventional methods (with ultrasonic bath and microwave oven) were used for the extraction of the polyphenols from seeds. The optimal conditions for the production of GSE were - magnetic stirrer, 70% aqueous ethanol, 3 h, room temperature. The extraction yield and total phenol content of the obtained extract were 12% and 111.22 mg gallic acid/g dry weight, respectively. The contents of total flavonoids (TF), procyanidins (PC), total anthocyanins and ascorbic acid of the GSE were determined. The obtained GSE was rich in TF (51.50 mg quercetin/g) and PC (170.45 mg catechin/g). Antioxidant capacities of the extract were evaluated by 2,2-diphenyl-1-picrylhydrazyl (579.33 μM Trolox/g) and 2,2′-azino-bis (3ethylbenzothiazoline-6-sulfonic acid) assays (2203.50 μM Trolox/g). The extract has a high antimicrobial effect against B. cereus and B. subtilis. The obtained Pinot Noir GSE will be suitable additive for food products.