Identification of glucomannan and oxalate content in the dasheen-type taro tuber ( Colocasia esculenta var esculenta) during post harvest storage

Abstract

Taro has a starchy root as an energy source due to the complex carbohydrates and a valuable source of essential nutrients. Glucomannan is a potential non-starch polysaccharide found in taro tubers; however, it also contains oxalate, an antinutrient that causes itching. The presented study aimed to investigate the degradation of glucomannan and oxalate in the taro tuber during post-harvest storage. The experiments were conducted in a randomized complete block design with two factors and three replications. The first factor was the source of the taro tuber, consisting of two cultivars from three fields of harvested taro. The second factor was storage duration, namely 2, 4, 6, 8, 10, 14, 12, and 16 days after harvesting. The determined glucomannan content followed the gravimetric method, whereas the spectrophotometric approach was used to analyse the oxalate. The result indicated that the origin of the taro tuber and the storage duration significantly influenced the oxalate content, whereas glucomannan was affected only by the location of the tuber harvested. The contents appeared degraded during 16 days of storage. The glucomannan in the taro tuber slightly declined but was slower than the oxalate reduction.