以國產稻米取代麵粉製作麵包之研究

Abstract

本研究包含米穀粉磨粉性質探討以及米穀粉或米飯取代麵粉製作米麵包(35% (烘焙百分比)米穀粉取代)兩大部分。原料選用市售台稉9號兩批(TK9及TK9II)、市售台稉9號白粒米(TK9IIc)、市售糯米(CW)、市售一般白米兩批(CR及CRII)、市售白粒米(CCR)、市售高直鏈米(CHA)、市售碎米(BR)、脆稈秈米(IR64)十種國產稻米，配合三台磨粉機(MA、MB及MC)五種磨粉條件(MA1、MA2、MB1、MB2、MB3及MC)進行試驗。分別探討米種、米粒調濕處理與磨粉設定對米穀粉糊液黏度性質、粒徑分布及破損澱粉含量之影響。並選用CW、CR、CCR、CHA及IR64米穀粉進行一系列之烘焙試驗：(1)比較不同米種以相同製程製作、(2) 比較不同米種製作相同比體積之麵包、(3)以糯米及高直鏈米配製序列直鏈澱粉含量之米穀粉、(4) 以糯米、白米及高直鏈米配製序列直鏈澱粉含量之米穀粉、及(5)由米飯取代生米穀粉，分別用以製作35%米穀粉及35%米飯(烘焙百分比)取代之米麵包，再以質地剖面分析法(texture profile analysis, TPA)評估新鮮麵包及其儲藏後之品質。實驗結果顯示，磨粉機MA所製米穀粉，具有低破損澱粉含量(3.96–6.73%)但粒徑較粗(148.4–225.7 μm)之特性；MB所製米穀粉之破損澱粉含量最高(13.52–38.37 %)，粒徑大小居中(58.6 – 114.1 μm)；MC所製米穀粉特性為破損澱粉含量居中(12.77–25.70%)，但平均粒徑最小(47.1-53.8 μm)。不同米種中以CW具有最高之破損澱粉含量，CHA破損澱粉含量最低；而粒徑大小則與米種無一定之趨勢。調濕處理可改變磨粉機MB之磨粉性質，降低米粒水分含量可降低米穀粉之破損澱粉含量；但調濕處理則對磨粉機MC所製備米穀粉之破損澱粉含量無影響。烘焙試驗結果顯示，適合製作米麵包之米穀粉應具有低破損澱粉含量且直鏈澱粉含量介於10 – 15%之特性。製作烘焙產品時，破損澱粉含量越高則比體積越小；直鏈澱粉含量和硬度呈現正相關，但不影響比體積。相同製程下，以CCR米穀粉製作之麵包，其硬度及彈性參數與控制組最接近。所有米穀粉麵包經儲藏後硬化速率皆高於控制組，但可藉由配粉控制初始硬度，改善儲藏後米麵包之品質。米飯麵包質地柔軟且富有特殊甜味，但對於米種及製程要求較高。官能品評結果顯示，米穀粉麵包及米飯麵包在所有項目得分皆與控制組相近甚至更高，顯示米穀粉麵包及米飯麵包極具開發潛力。

The objectives of this study included the rice flour milling test for the rice bread making and the rice bread making test with 35% rice flour and cooked rice (on flour basis) substituted. About the rice flour milling test, the effects of different rice varieties, rice tempering and milling conditions on the pasting properties, particle size distribution and damaged starch content of rice flours were investigated. Ten domestic rice (commercial japonica rice, TK9 & TK9II; commercial waxy rice, CW; commercial common rice, CR & CRII; commercial chalky rice, CCR; commercial high amylose rice, CHA; japonica chalky rice, TK9IIc; broken rice, BR; indica rice, IR64) were grounded by three mills (MA, MB and MC) with five settings (MA1, MA2, MB1, MB2, MB3 and MC) were used in this study. CW, CR, CCR, CHA and IR64 rice flours were used for bread making test of 35% rice flour or cooked rice substituted bread. The bread making test included making rice breads (1) with different rice flours by the same processes, (2) with different rice flours and keeping the same specific volume, (3) with different amylose content rice flours blending with CW and CHA, (4) with different amylose content rice flours blending with CW, CR and CHA, and (5) with cooked rice. The quality of fresh made and aged breads were evaluated by texture profile analysis (TPA). The results of milling test indicated that the rice flours milled by MA were low in damaged starch content (3.96–6.73%) with large particle size (148.4–225.7 μm); the rice flours milled by MB were high in damaged starch content (13.52 – 38.37 %) with medium particle size (58.6–114.1 μm); the rice flour milled by MC were medium in damaged starch content (12.77 – 25.70%) with small particle size (47.1-53.8 μm). Compared damaged starch content of rice flours, CW was the highest and CHA was the lowest. There is no correction between rice varieties and particle size. The influence of tempering treatment on the damaged starch content of rice flour was significant on the MB, which the lowest moisture content of rice granules had the lowest damaged starch content of rice flour. While, the damaged starch contents of rice flours milled by MC were not influenced by the tempering. The results of baking test indicated that the ideal rice flours for bread making should contain low damaged starch content and have the amylose content between 10–15%. The higher damaged starch content resulted in the smallest specific volume of rice bread. The amylose content of rice flour was positive with the hardness of rice bread, but no correction with the specific volume of bread. With the same bread making process, the TPA values of CCR bread was the most similar to the control, which was made with wheat flour. Although the hardening rates of all rice breads were higher than the control, blending the rice flour with low amylose content could improve the storage quality of aged rice bread with low initial hardness of rice bread. Cooked rice breads, made with special rice specie by modified processing processes, had soft texture and rich in special sweet taste, which were favored by most panelists. To the results of sensory evaluation, rice breads made with rice flour and cooked rice got close or higher scores on all subjects, indicating that the rice breads made in this studies have great potentials for the marketing.