Acid hydrolysis of corn starch genotypes. II. Impact on functional properties

Abstract

The impact of the acid modification on the molecular properties of two corn starch genotypes (high amylose corn starch: HACS, amylose (AM) content about 70% w/w; waxy corn starch: WxCS, AM content < 2% w/w) was reported comprehensively in a previous study. Based on that, the data referring to the solution and the gel properties, which are important attributes for the application in e.g. gelled sweets, were presented in the present study. Polydisperse solutions were prepared by pressure cooking. The hot paste viscosity (η) of the concentrated native HACS solution was significantly higher compared to WxCS. The reduction of the weight average molar mass (Mw) due to acid-thinning reduced η by trend (WxCS). Native HACS tends to form very stable gels. However, acid-thinning reduced the stability of the gel system slightly. The non-gelling character of the WxCS wasn't changed either by the modification. Furthermore, the light transmittance differed strongly depending on the type of starch variety. Independent of the state, i.e. either the freshly prepared solution or the corresponding cold stored product, the HACS samples were generally turbid and the WxCS samples of high clarity. The specificity of the functionality in blends basically behaved according to the mixing ratio of the two genotypes. However, increasing relative portions of amylopectin (AP) reduced the ability to inter-chain associations and resulting gel hardness disproportionally on the one hand, but the light transmittance didn't increase adequately on the other hand.