Stability of yam starch gels during processing

Abstract

To evaluate their aptitude to be used as functional ingredients, twenty one varieties of yam starches of Côte d'Ivoire were submitted to different technological stress such as high temperature treatment, long term freezing and refrigeration, high speed shearing and acidic treatment, in comparison with commercial modified starches. The gel of “kangba” starch (D. Cayenensis-rotundata) is the most stable during thermal processing. The cultivar “Daminangba” (D. alata) which present the clearest gel (63 % of clarity) is also the most stable during refrigeration with a low syneresis (26%) at 4°C.The “Esculenta 7” cultivar (D. esculenta) shows the weakest value of syneresis at -20°C. The gel of D. dumetorum species is the strongest under acidic condition with 8% of viscosity decrease from pH 7 to pH 3, whereas the “Bodo” cultivar (D. alata) gel shows good resistance to shearing with 31% fall of viscosity from 160 rpm to 900 rpm on the RVA. The “Sopèrè”, “Lopka” and Kponan cultivars (D. Cayenensis–rotundata) present the strongest viscosities in all the technological treatments.

Key Words: Yam starch, modified starch, functional properties, gel stability.

African Journal of Biotechnology Vol.4(1) 2005: 94-101