Rapid Estimation of Fruit Starch and Soluble Sugar Concentrations in Kiwifruit

Abstract

Experiments investigating kiwifruit [Actinidia deliciosa (A. Chev) C.F. Liang et A.R. Ferguson var. deliciosa] maturation were undertaken requiring the determination of total soluble sugar (TSS) and starch concentrations in numerous fruit samples. The phenol-sulfuric acid assay was judged to he a convenient method for determining TSS from tissue extracts and gave results similar to those obtained by high-pressure liquid chromatography. The starch procedure adopted involved gelatinizing fruit tissue using hot water and a thermostable α -amylase (Termamyl); hydrolizing starch using amyloglucosidase; and determining glucose using glucose oxidase. The methods enabled one person to analyze up to 40 kiwifruit samples for TSS and starch concentrations during 9 hours and likely will be applicable to research concerning fruit development and maturation.