國產高直鏈澱粉玉米之機能性穀粉研發

Abstract

以農試所新育種並安全生產 (good agriculture practice, GAP) 之高直鏈澱粉玉米(ae-mutant) 為試驗原料，建立高直鏈澱粉玉米之玉米全穀粉研磨技術。經由玉米全穀粉之理化性質測定與分析結果，建立高直鏈澱粉玉米之全穀粉規格，並進行玉米全穀粉貯存穩定性之評估。結果顯示，最適玉米籽粒研磨條件為，調適水分含量為13%，但經濕熱處理後之玉米籽粒由於種皮變韌，第一次研磨後，仍有許多較粗粉粒殘留在磨粉機底層，因此，為達穀粉之粒徑範圍 (小於212 μm)，必須將此部分再次研磨，以提高全穀粉之收率。相較於對照組 (未經熱處理者)，先以乾熱及濕熱處理玉米籽粒後，再行磨粉所製得之全穀粉，在40℃加速儲藏12 週後，全穀粉酸價僅些微上升，顯示磨粉前熱處理確實可抑制籽粒內之氧化酵素活性，使研磨後全穀粉內之油脂不至於快速氧化酸敗。而糊液黏度性質結果顯示，濕熱處理並不會造成糊液黏度的差異，但乾熱處理則會使全穀粉黏度大幅下降。外觀及氣味上，濕熱處理並不會造成穀粉顏色及風味的改變，而乾熱處理者則會使全穀粉色澤呈深褐色且有烤焙香味。濕熱處理對研磨樣品之一般成分上則沒有明顯之改變，細微的差異可能與磨粉過程中部分粉體的損失有關。機能性成分分析結果顯示，濕熱處理會使總黃色色素及總酚類化合物含量下降，而葉黃素及玉米黃素含量上升。消化率分析結果顯示，高直鏈澱粉玉米全穀粉之抗性澱粉含量較硬質玉米全穀粉為高且具有較低的eGI 值，顯示前者可供作低升糖指數產品之開發應用。 Corn (Maize) is the most important cereal crop in the world. The health benefits of whole grains heve been scientifically proven and widely repoted, thus the development of the whole grain products have gained much high attention in the food industry. The dry milling corn priducts served as main dishes and used for snack-making have a long histroy. While most of these corn-based produscts are prepared from the degermed and debraned corns. The crucial problem of the milled whole grain products is to prevent them from the rancidity. Therefore, the objective of this study is to evaluate the effects od dry- and wet- heating treatments before milling process on the storage stability and psyciochemical properties of whole grain products. In the experiment, tempering the corn kernels to moisture content of 13% could obtained the most homogeneous and finest whole corn flour. In addition, both dry- and wet- heating pretreatments are able to produce the storage stable whole corn flour resulting from low aw and acid value durng 12 weeks of storage at 40℃. Nevertheless, dry-heating pretreatment would decease pasting viscosity and developing brown color. The wet- pretreatment would not change the properties of whole corn flours, similar to the properties of whole corn flour without pretreatment. After the dry miling, there are no significant differences in the chemical compositions between whole corn flours with and without pretreatment. However, the contents of total yellow pigment of whole corn flour milled from the pretreated kernels are slightly decreased. The in vitro digestibility of the whole corn flour reveals that the whole high amylose corn flours have high content of resistant starch with low eGI value compared with normal corn variety TNG 1. Base on the results mentioned above, high amylose corn has great potentials of ingredients for development of the functional food products.