The effect of concentration and botanical source on the gelation and retrogradation of starch

Abstract

A BS TRA CTThe changes in shear modulus of pea, wheat, maize and potato starch gels with time, at concentrations between 10 and 40% w/w, were followed. In this range, the cooling of gelatinised dispersions of starch resulted in turbid, elastic gels. The initial rate of development of stiffness of the gels followed the order: pea>maize>wheat>potato, and was related to the amount of amylose solubilised during gelatinisation. The initial gelation was not reversed on heating to 100°C. There was also a long-term increase in gel stiffness, which was thermally reversible. This long-term increase, linked to a crystallisation involving amylopectin, followed the order: pea>potato>maize> wheat. With increasing starch concentration this latter process becomes more important.

The effect of hydroxypropylation on the structure and physicochemical properties of native, defatted and heat-moisture treated potato starches

“…(Orford at a/., 1987) observed for 30% starch gels from various botanical sources followed the order: pea> maize> wheat> potato. The dependence of initial rate of increase of the modulus on the botanical sourcecan be accounted for by the different amounts of amylose that are solubilized during gelatinization.…”

“…Despite the numerous investigations that have been carried out to study retrogradation, the exact mechanism of retrogradation, particularfyatthe molecular level still remains unclear. The rate and extent of retrogradation is influenced by many factors such as botanical source (Orford at al., 1987;Jacobson et al, 1997), chain length of amylose and amylopectin (Gidley & Bulpin, 1989;Clark et al, 1989), water content in gel (longton & leGrys, 1981;, cooking and cooling conditions (Kimetal., 1993), storage temperature (Jankowski & Rha, 1986;Jang & Pyun, 1997) and the presence of solutes such as sugars, lipids and salts (Russell & Oliver, 1989;Katsuta et al, 1992a,b;Huang & White, 1993;Conde-Petit & Escher, 1994).…”

Influence of glycerol and water content on the structure and properties of extruded starch plastic sheets during aging

“…[19][20][21][22][23][24] temperatures during usage and storage. This Glycerol containing starch plastics were shown to leads to differences in water content and to differrecrystallize into various crystal structures deences in properties such as crystallization behavpending on processing as well as storage condiior.…”

Physico-chemical characterisation of sago starch

“…All starches are made up of these two polysaccharides. The ratio varies with the starch source but is typically 20 : 80 amylose to amylopectin (Orford et al, 1987). For example corn starch has approximately 28% amylose; genetically manipulated high amylose corn starch can contain about 70% amylose while genetically modified waxy corn contains 90%-100% amylopectin (Kennedy et al, 1983;Cowburn, 1989).…”