Heat and moisture
Water content is an important factor that affects formation of RS.
Repeated heat/moisture treatment is associated with a decrease in
the hydrolysis limit of pancreatic -amylase and increased formation
of RS. Maximum RS yield was obtained at a starch:water ratio
of 1: 3.5 (w/w) (Sievert and Pomeranz 1989b) and a heat treatment
at 18% moisture gave increased levels of the degree of crystallinity
of normal and waxy starches and thus reduced enzyme susceptibility.
However, at 27% moisture, starch degradation to some
extent made areas of starch more accessible to enzyme attack.
Thus, proper heat treatment could be used as a method of preparation
of RS (Franco and others 1995). In addition, higher temperature
and less water results in type A configuration, whereas lower
temperature and high water content results in type B configuration
(Wu and Sarko 1978).