Yeast fermentation of apple and grape pomaces affects subsequent aqueous pectin extraction: Composition, structure, functional and antioxidant properties of pectins. (December 2022)

• Record Type: Journal Article
• Authors: Xu, Fangzhou; Zhang, Shikai; Waterhouse, Geoffrey I.N.; Zhou, Tao; Du, Yuyi; Sun-Waterhouse, Dongxiao; Wu, Peng
• Is Part Of: Food hydrocolloids. Volume 133(2022)
• Publication Date: 2022-12
• Subjects: Fermentation -- Aqueous extraction -- Green processing -- Emulsifier -- Methoxylation; Hydrocolloids -- Periodicals; Food additives -- Periodicals; Colloïdes -- Périodiques; Aliments -- Additifs -- Périodiques; Colloids; Food additives; Periodicals; Electronic journals; 664.06
• DOI: 10.1016/j.foodhyd.2022.107945
• Languages: English
• ISSNs: 0268-005X

Abstract

Abstract: Fruit waste valorisation to generate value-added pectin products is an active research area. In this study, pectin products from unfermented apple/grape pomace (AP/GP) and from fermented apple/grape pomace (FAP/FGP) were prepared via extraction with aqueous citric acid at 60 °C. Fermented apple/grape pomace was produced via yeast fermentation. Compared with GP, AP had a higher pectin yield, GalA and protein contents, amounts of HG and RG-I, Mw, branching degree and size of neutral side chains, but lower degree of methoxylation (DM), linearity of pectin and phenolic/anthocyanin content. AP, FAP and GP had a DM higher than 50%, whilst FGP had a DM lower than 50%. Fermentation decreased pectin's yield, DM and contents of phenolics and anthocyanins, while altering significantly the monosaccharide profiles of the pectins. Fermentation yielded pectins with smoother surfaces and more amorphous structures. Fermentation of apple pomace decreased HG by 58% and caused a 2.39-fold increase in RG-I, whereas, fermentation of grape pomace decreased HG and increased RG-I to a lesser extent. All these fermentation-induced changes caused differences in shear-thinning behavior, thermal stability, viscoelasticity and antioxidant activities between AP/GP and FAP/FGP. FAP and FGP aqueous dispersions (2.0–5.0%) had lower viscosities than AP and GP dispersions. All pectin samples can be used as emulsifiers, gelling agents and rheology modifiers. FAP and FGP were the most and least effective emulsifiers, respectively, at concentrations of 1.0–2.0% w/v. All pectin samples possessed significant antioxidant activities. GP had the highest antioxidant capacity (at 20 or 30 mg/mL exhibiting comparable activity to vitamin C). Graphical abstract: Image 1 Highlights: Pectins were isolated from fermented/unfermented apple and grape pomaces. All the pectins are emulsifiers and rheology modifiers with varied gelling capacities. Fermentation yielded pectins with smoother surfaces and more amorphous structures. Unfermented grape pomace pectin had the highest antioxidant activity. Fermentation greatly improved the emulsifying properties of apple pomace pectin.