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Abstract: Gelatinized waxy and normal corn starches at various concentrations (20–50%) in water were stored under temperature cycles of 4°C and 30°C (each for 1 day) up to 7 cycles or at a constant temperature of 4°C for 14 days to investigate the effects of temperature cycling on the retrogradation of both starches. Compared to starches stored only at 4°C, both starches stored under the 4/30°C temperature cycles exhibited smaller melting enthalpy for retrogradation (ΔH r), higher onset temperature (T o), and lower melting temperature range (T r) regardless of the starch concentration tested. Fewer crystallites might be formed under the temperature cycles compared to the isothermal storage, but the crystallites formed under temperature cycling appeared more homogeneous than those under the isothermal storage. The effect of starch content on the retrogradation was greater when the starch gels were stored under cycled temperatures. The reduction in ΔH r and the increase in conclusion temperature (T c) by retrogradation under 4/30°C temperature cycles became more apparent when the starch concentration was lower (20 or 30%). Degree of retrogradation based on melting enthalpy was greater in normal corn starch than in waxy corn starch when starch content was low. [Copyright &y& Elsevier]

Abstract: Waxy maize starch gels prepared from 40% starch solids were retrograded, either isothermally at 4°C or at cycles of 4°C and 30°C (2 days each), for 16 days. The properties of retrograded starch gels were determined by differential scanning calorimetry (DSC), X-ray diffraction patterns, textural properties, and in vitro digestibility. The starch crystals formed in the gel stored under the 4/30°C cycled conditions melted at a higher onset temperature with a narrower endothermic peak and a lower enthalpy than those formed under constant temperature storage at 4°C. No differences between the two storage conditions were observed in the X-ray diffraction patterns of retrograded starch. The glass transition temperature increased and the ice melting enthalpy decreased throughout the retrogradation process regardless of the temperature cycle. The starch gel stored under the cycled temperature conditions exhibited slightly lower and greater ice melting enthalpy than those stored under the constant 4°C. The starch gel retrograded at the cycled temperature conditions remained softer than those stored under constant temperature with similar springiness. The cycled temperature storage induced a greater amount of resistant starch and reduced the in vitro glycemic index more effectively than the isothermal storage condition. [Copyright &y& Elsevier]

We investigated both the distribution of protein, ash and starch in legume (chickpeas, smooth and wrinkled peas) cotyledons, and the soaking and cooking characteristics, including gelatinization and retrogradation, of the starch. There were large differences in composition between different types of legumes and also between the outer and inner parts of legume cotyledons. Wrinkled peas exhibited much higher water absorption during prolonged soaking and there were higher hardness value determined for cooked seeds compared with chickpeas and smooth peas. While the hardness of cooked seeds decreased continuously as cooking time increased to 110 min, all legume starch was fully gelatinized after cooking for 70 min. [ABSTRACT FROM AUTHOR]