The effect of temperature cycling on the amylopectin retrogradation of starches with different amylopectin unit-chain length distribution

Cassava sour starch is a typical food ingredient from some South American countries, produced mainly in Brazil and Colombia and it shows high expansion when baked. It is known that sun-drying fermented starch is essential. Recently degradative oxidation has been considered as possibly related to chemical changes on cassava starch and was evoked as a probable cause for baking property. We produced some chemically oxidized samples presenting baking property to be compared with lactic acidified and sun- or oven-dried ones, as well as with commercial cassava sour starch and native cassava starch. All the samples were analyzed by using FTIR spectroscopy associated with chemometric data processing. Successful prediction of starch expansion value was achieved by partial least square regression of FTIR spectral data. The results of both qualitative and quantitative spectral analyses showed that presence of carboxylate groups (1600 cm-1) on cassava starch as well as some other changes in the region around 1060 cm-1 of mean normalized spectral data are essential for baking property. The degradative oxidation is assumed to take place on the C¯O bond relative to carbon 1 and oxygen 5 of the cyclic part of glucose at 1060 cm-1.