engleski

Crosslinking and acetylation of wheat and potato starches

Starch is widely used in the food and non-food industry due to unique chemical, physical and structural properties. Native starch has limitations in food industry applications such as high tendency toward retrogradation, low thermal resistance and shear resistance. Therefore, starch is often modified in different ways (chemical, physical or enzymatic) to change and improve its performance. The aims of this research were: (a) to isolate native starch from two sorts of wheat, (b) to obtain different modified starches (wheat and commercial starch of potato) through acetylation and cross-linking (c) to explore rheological and thermophysical properties of native and the obtained modified starches with the purpose of defining the possible application. Rheological and thermophysical properties were measured with Brabender Micro-Visco-Amylograph and Differential Scanning Calorimeter. The measurement results showed that wheat and potato starches acetylated with an 8% acetanhydride had lower gelatinization and enthalpy temperatures, as well as retrogradation enthalpies (after 7 and 14 days of storage) than native starches. Pastes of acetylated potato starch had lower viscosity levels compared to native starch at 50ºC, whereas pastes of acetylated wheat starches at the same temperature had higher levels in relation to the native ones. Cross-linking of potato starch with sodium tripolyphosphate (2, 5 and 5% STPP) resulted in decrease of gelatinization temperature and enthalpies as compared to native starches, where a 2, 5% STPP modification had greater effect. Cross-linking of wheat and potato starches lowered the retrogradation enthalpy of all sampless after 7 and 14 days of storage, and raised the viscosity levels of all samples.

starch; acetylation; cross-linking; STPP; rheological properties; thermophysical properties

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