酸或酶处理对米饭抗性淀粉含量和性质的影响

Effects of Acid Treatment and Enzymatic Treatment on the Content and Properties of Resistant Starch in Boiled Rice

抗性淀粉中第3型抗性淀粉属于回凝性淀粉,可经由各种加工处理提高其含量,以台农71号精白米为材料,研究开发一种直接提高米饭中第3型抗性淀粉含量的制程,直接在米饭内进行酸处理或酶处理,然后检测抗性淀粉含量的变化,并进行微差扫描热分析、X射线衍射以及热稳定性测定。结果显示:直接在米饭内进行酶处理之制程可以使米饭中抗性淀粉的含量由原来的0.4%提高至20%以上;微差扫描热分析结果显示加工后的米饭样品起始糊化温度(To)、相变高峰温度(Tp)和相变焓(ΔH)均高于未经处理米饭样品,显示淀粉结晶结构已经改变;X射线衍射显示高抗性淀粉含量的米饭的淀粉结晶型态改变,已经由Type A转变成Type V淀粉,而热稳定性的测定显示经由此制程提高的抗性淀粉是热稳定的。

Resistant starch is difficult to digest due to its physical characteristics,which can play important roles in blood glucose regulation,body weight control,cancer prevention and other physiological activities.Resistant starch has been classified into four categories depending on resistance causes.Type III resistant starch（RSIII） is a retrograded and non-granular starch that can be generated by various types of processing.In this study,the formation of RSIII in boiled rice was explored based on acid treatment and pullulanase treatment.Both treatments could increase the content of resistant starch in boiled rice.Differential scanning calorimetry analysis revealed increased initial pasting temperature,phase transition peak temperature and phase transition enthalpy of starch in boiled rice due to the increased content of resistant starch.X-ray diffraction showed that crystal structure of resistant starch in boiled rice converted into Type V from Type A.Moreover,the resistant starch achieved by these treatments revealed excellent thermal stability.