EFFECTS OF LOW‐ AND ULTRALOW‐TEMPERATURE FREEZING ON RETROGRADATION AND TEXTURAL PROPERTIES OF RICE STARCH GEL DURING STORAGE

Abstract

ABSTRACTIn the current research, rice starch gel was frozen by low temperature (−20, −30 and −60C) or ultralow temperature (−100C), and then stored at 4C for 21 days or −18C for up to 5 months to evaluate the retrogradation and textural properties. Retrogradation enthalpy (ΔHr) of rice starch was determined by a differential scanning calorimetry, and textural properties were determined by a texture analyzer. The results showed that low‐temperature and ultralow‐temperature freezing can effectively retard starch retrogradation during freezing process, while the freezing process has no significant influence on the thermal properties of rice amylose‐lipid complex during storage. On the other hand, retrogradation and textural properties of rice starch gel were related to amylose and amylopectin ratio when stored. Therefore, the amylose and amylopectin properties and freezing process have a synergistic effect on retrogradation and textural properties of rice starch gel during storage.PRACTICAL APPLICATIONSStarch retrogradation is an unavoidable phenomenon for the texture of many ready meals, which is a major problem for industry to produce high‐quality starch‐based ready‐to‐eat meals. The low‐ and ultralow‐temperature freezing combined with frozen storage can effectively retard rice starch retrogradation and maintain the textural properties of rice starch gel for at least 5 months, and this optimum method is very useful for food industry to produce high‐quality starchy foods.