EFFECT OF POLYHYDROXY COMPOUNDS ON STRUCTURE FORMATION IN WAXY MAIZE STARCH GELS - A CALORIMETRIC STUDY

The effects of polyhydroxy compounds (PHCs) on structure formation in ageing waxy maize starch gels were investigated by measuring the retro gradation endotherm (Delta H) using calorimetry. Changes in retrograda tion kinetics observed by addition of PHCs at a weight ratio of starch :PHC:water of 1:0 5:1.5 were solute specific. In the homologous series of glucose oligomers, maltotriose exhibited the largest inhibitory ef fect, while maltooctaose promoted retrogradation. Among various pentos e and hexose sugars, ribose and talose, respectively, were the most ef fective in retarding retrogradation. Fructose led to increased rates o f chain ordering, particularly at high concentrations. The results wer e correlated with literature data of several physicochemical propertie s of PHCs in solution. Strong linear relationships were shown between the effect of sugars on retrogradation endotherm and the hydration cha racteristics of these solutes. It was further suggested that compatibi lity of sugar with the water structure, as governed by the stereochemi stry of the main sugar conformers in solution, is an important determi nant of amylopectin stability in the composite gel matrix; i.e. PHCs w hich disturb very little the hydrogen-bonded network of water are also effective in inhibiting retrogradation.