Novel pectin present in new olive mill wastewater with similar emulsifying and better biological properties than citrus pectin

Abstract

Alperujo, a semi-solid by-product from the olive oil industry, is currently subjected to a novel industrial treatment, which consisted of gentle heating at 50–80 °C for 1–2 h, followed by a new three-phase centrifugation system that gave alperujo oil, olive pomace and aqueous by-products. This process is a prerequisite to reduce the humidity of the resulting solid to enable its use as biomass, and allows for the recovery of a new olive mill wastewater, which was used in this work for the isolation of water-soluble polysaccharides. Two polysaccharide-enriched extracts were obtained by ethyl alcohol precipitation with 40 and 80% (v/v) EtOH from the new aqueous by-product and purified. The pectic material presented a high molecular size and a low percentage of methyl esterification and acetylation. In comparison with commercial pectins, the extracts had better oil holding capacity and similar emulsifying activity to that of citrus pectin. For the first time, bile-acid binding and glucose retardation activity were considered for the pectic material isolated from olive by-products, which showed better results than commercial pectins. In addition, the antioxidant activities of these extracts were investigated using various in vitro assays and the two raw polysaccharide extracts, rich in associated polyphenol compounds, exhibited a stronger antioxidant activity than that observed for citrus and apple pectins. Thus, polysaccharide-enriched extracts from gentle heat treated alperujo have suitable emulsifying properties for commercial uses and the important bioactive properties of antioxidant dietary fiber.