甘藷定溫加熱過程澱粉糖化研究

Abstract

甘藷是台灣用途廣泛的糧食作物之一，在甘藷在加熱過程中甜度會有所增加，這是由於甘藷烘烤過程中甘藷內澱粉被轉化為醣類的結果。透過烘烤加熱加工處理程序後之甘藷所含糖分較生藷為高，此現象並非取決於甘藷本身澱粉及可溶性糖含量多寡，而是由甘藷內β-澱粉酶(β-amylase)活性高低之差異所影響。本研究為甘藷烘烤加工過程之研究提供一反應迅速之溫度控制系統，此溫度控制系統主要分為溫度感測與升溫控制兩個部分，利用熱電偶量測甘藷樣品於烘烤時之升溫狀況，並將升溫狀況輸入至電腦Labview程式進行PID控制運算，在將訊號輸出至電源控制晶片，利用電源控制晶片控制電流來控制致冷晶片的加熱與散熱，以此方式定溫控制。用熱傳導公式輔以實驗數據推算甘藷熱傳導係數，推算之熱擴散係數為1.00308*10-7，同時以電腦軟體COMSOL 5.0進行熱傳模擬，模擬甘藷於烘烤過程中升溫狀況。利用上述溫度控制系統以定溫烘烤的方式，對甘藷進行不同烘烤溫度(50~90°C)及不同烘烤時間(10~50分鐘)之試驗，檢測在不同試驗條件下甘藷水分、澱粉及可溶性糖之含量，結果顯示於80°C時甘藷內糖份含量上升最高，由80°C加熱50分鐘的結果顯示甘藷含糖量上升至約25%。

During the process of baking, sugar content of sweet potato is increasing. As a result sweetness of the sweet potato is increasing. This phenomenon called Saccharification is not determined by the original starch content of the sweet potato and sugar content of the sweet potato, either. It is determined by the activity of β-amylase in sweet potato. The activity of β-amylase is affect by the baking temperature. This study provides a temperature control system. The baking temperature is monitored by the temperature control system and the temperature signal will be calculated by PID controller which is written in Labview software. Then the computer will deliver the result signal to the current-controlling chip which is used to control the thermoelectric cooling module. The thermoelectric cooling module is applied to control the baking temperature at constant temperature. The heat transfer equation is applied with experiment data to calculate the thermal diffusivity of the sweet potato. The calculated thermal diffusivity is 1.00308*10-7. A heat transfer simulation is built by COMSOL Multiphysics to simulate the change of temperature. The temperature control system is applied to perform the experiments with different baking temperature at the range of 60~90°C and length of time from 10 ~50min. The water, starch and sugar content of the sweet potato are examined in each experiment. The result reveals that when the temperature is controlled at 80°C, the sugar content of the sweet potato will increase more. In the condition at 80°C and baking 50min, the sugar content of the sweet potato will increase to about 25%.