Quality of chilled and frozen starch gels as affected by starch type, highly concentrated sucrose and coconut milk

Abstract This research aimed to evaluate effects of starch source, sucrose at high concentration and coconut milk on physical properties of chilled and frozen starch gels, considered as traditional Thai dessert models. Gel containing 15% w/w of starch was prepared from rice starch, tapioca starch or blended rice starch/tapioca starch (1:0.85 w/w) mixed with water, 45oBx sucrose solution or coconut milk. The result showed that rice starch gel stored at 4oC had highest hardness, degree of syneresis and melting enthalpy of the retrograded structure (ΔHret). Degree of syneresis of frozen rice starch gels subjected to several freezing-thawing cycles was also highest. Under chilled temperature storage, starch gels containing sucrose or coconut milk had higher hardness and denser gel structure, comparing to the starch gels in water. This textural change was due to greater degree of starch retrogradation, sucrose recrystallization and/or formation of amylose-lipid complex crystallites shown in X-ray diffractograms. However, addition of highly concentrated sucrose or coconut milk increased freeze-thaw stability of the frozen starch gels, as shown by decreasing degree of syneresis. Results from this study could be applied to formulate starch-based dessert with improved quality during chilled or frozen storage.