Extraction, characterization and gelling ability of pectins from Araçá (Psidium cattleianum Sabine) fruits. (December 2021)

• Record Type: Journal Article
• Authors: da Costa Amaral, Sarah; Roux, Denis; Caton, François; Rinaudo, Marguerite; Barbieri, Shayla Fernanda; Meira Silveira, Joana Léa
• Is Part Of: Food hydrocolloids. Volume 121(2021)
• Publication Date: 2021-12
• Subjects: Araçá -- Pectin -- Molecular structure -- De-esterification -- Gelation -- Rheology; Hydrocolloids -- Periodicals; Food additives -- Periodicals; Colloïdes -- Périodiques; Aliments -- Additifs -- Périodiques; Colloids; Food additives; Periodicals; Electronic journals; 664.06
• DOI: 10.1016/j.foodhyd.2021.106845
• Languages: English
• ISSNs: 0268-005X

Abstract

Abstract: Pectins from Araçá ( Psidium cattleianum Sabine) fruit pulp were extracted, purified and isolated, obtaining the Araçá Purified Pectin (APP) under its sodium form. Yield was found 3.5% w/w of the initial dried material. From titration, monosaccharide analysis after total hydrolysis and 1 H and HSQC NMR analyses, it was established that the pectins are formed of long galacturonic acid blocks (HG) partially methylated (degree of methyl-esterification – DM = 55.9 mol%) and acetylated (2 mol%) and RG-I blocks with side chains containing mainly arabinose and galactose. No gelation was observed in presence of calcium for the unmodified APP. Then, pectins were treated in alkaline conditions to de-esterify progressively the initial sample down to DM = 0 after 60 min of treatment. Each sample obtained was characterized by SEC and NMR demonstrating the stability of the main chains, where Rha, GalA and M w remained unchanged independently of the length of alkaline treatment. One of this sample (APP-15) was selected to test the gelling ability and rheological behavior. The gel was formed by dialysis against 1 mol L −1 CaCl2 and its rheological study allows to conclude that a homogeneous physical gel is formed stabilized by cooperative GalA − -Ca +2 junctions. Graphical abstract: Image 1 Highlights: Fine structure of Araçá pectin is established for the first time . De-esterification is performed in alkaline conditions without any change in Mw. Initially, it is non gelling pectin (DM ~ 60%) in acid and calcium excesses. The critical gelation concentration (~2 g L −1 ) is determined when DM decreases. Demethylated pectin form a strong gel as shown by rheological measurements.