The Effect of Solutes on the Gelatinization Temperature Range of Potato Starch

Abstract

The gelatinization behaviour of potato starch in an excess of water or solutions of sugars, other organic hydroxy compounds, or various inorganic salts was studied. The distribution of water and solutes between the external phase and the starch granules was measured by refractometry and a dye exclusion technique. When the limited water uptake of native starch granules is taken into account, the cooperative nature of gelatinization and the effect of water content on gelatinization behaviour can be explained solely on the basis of the Flory theory of polymer melting. Following the same argument, the effect of many solutes can be approximately described by the derived relationship between initial gelatinization temperature, water activity of the system and volume fraction of water in the granules.

Gelatinization and Solubility of Corn Starch during Heating in Excess Water: New Insights

“…The changes that take place during gelatinization have been attributed to water availability (9), crystal stability within granules (25), differences between amorphous and crystalline regions (26), and glass transition related progressive melting (27). However, aspects of these explanations are contradictory, and it is believed that enthalpic transitions during gelatinization represent numerous changes in starch granules (6).…”

The impact of heat-moisture treatment on the molecular structure and physicochemical properties of normal and waxy potato starches

“…Starch gives a biphasic endotherm during gelatinization at low moisture levels (water:starch volume fractions less than 0.45) (Donovan, 1979;Evans and Haisman, 1982;Nakazava et al• 1984). Donovan (1979) suggested that in the presence of less water, theendothermic transition is characterized as a solvent-aided melting of crystallites in the starch granules.…”

“…When excess water is present, the high temperature transition disappears (Donovan, 1979). Evans and Haisman (1982) proposed the "cooperative melting theory", which explains the bi-phasic endotherm as a result of crystallite stability within the granules. The granules containing the least stable crystallites start to change first upon heating.…”

“…This cooperative process happens quickly when there is sufficient water and gives a nan·ow or single DSC endotherm. At low moisture content,there is insufficient water for cooperative melting to take place (Evans and Haisman, 1982).…”

“…Several gelatinization mechanisms have been proposed to describe the changes occurring during heating of starch granules in excess water (Biliaderis, etaf., 1986;Blanshard, 1987;Donovan, 1979;Evans and Haisman, 1982;Liu et af., 2002;Marchant and Blanshard, 1978;Waigh et af., 2000b). Donovan (1979) proposed a model for gelatinization in excess water whereby the swelling of the amorphous regions of the granule facilitated the "stripping" of starch chains from the surface of crystallites, thereby disrupting crystalline order.…”