Extraction and Characterization of Highly Gelling Low Methoxy Pectin from Cashew Apple Pomace

Investigation on the pectic substances of cashew (Anacardium occidentale L.) apple under different acid-extraction conditions (pH 1.0, 1.5, and 2.0) showed that more than 10%-25% of A. occidentale pectins (AOP) could be extracted, depending on the extractant strength. The extracted AOP contained high amounts of galacturonic acid (GalA: 69.9%-84.5%) with some neutral sugars of which rhamnose (Rha: 1.3%-2.5%), arabinose (Ara: 2.6%-5.4%), and galactose (Gal: 4.7%-8.6%) were the main constituents. The degree of methoxylation (DM) was in the range of 28%-46% and was only slightly affected by the extractant strength, thereby indicating isolation of naturally low methoxy pectins (LMP). In terms of gelling capability, AOP yielded firmer Ca2+-mediated LMP gels than commercial citrus LMP with comparable DM. Cashew apple pomace, therefore, appears to be a potentially viable source for possible production of "non-chemically or enzymatically-tailored" LMP.