2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

The well known increase of the starch gelatinisation temperature in the presence of sugars can be partly explained using the food polymer science approach involving the non-equilibrium aspect of the gelatinisation process and the role of the glass-rubber transition (Slade and Levine, 1987). In this theory, the role of sugar is understood in terms of the decrease of the plasticising properties of the aqueous phase and the subsequent increase of the glass transition temperature (T(g)). However the location of the T(g) of the amorphous part of starch and the extent to which it controls gelatinisation is not fully understood. The purpose of this study is to use annealing to assess the role of the glass-transition in controlling gelatinisation and to verify the antiplasticising effect of sucrose as a mechanism for increased gelatinisation temperature using differential scanning calorimetry (DSC). The results obtained on wheat starch-water in excess water content conditions (1g of water per g of starch) and stored at different temperatures below that of the onset of gelatinisation for 24h, showed that annealing occurred only above 25 C. When sucrose was added to the system, the minimum temperature at which annealing occurred was increased. This increase was related to the concentration of sucrose and was reduced when sucrose was replaced by fructose. Over this timescale, we defined the minimum temperature at which annealing occurred as T(g). This approach provided a useful insight into the role of the glass-transition in controlling gelatinisation and the antiplasticising effect of sugars as a mechanism for increased gelatinisation temperature.