糯性米穀粉及預糊化處理對麵糰性質及饅頭品質之影響

Effects of Waxy Rice Flour and Pregelatinized Wheat Flour on the Dough Property and Quality of Steam Bread

劉仲華(Chung-Hua Liu)

指導教授 ： 賴喜美

國立臺灣大學/生物資源暨農學院/農業化學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.02187

摘要

本試驗主要分為將糯性米穀粉及麵粉混合為組合性麵粉以製備饅頭，以及將部分麵粉預糊化以製備饅頭兩大部分，糯性米穀粉對麵粉之取代量及預糊化之麵粉比例同樣設定為10、20及30%。以糯性米穀粉取代部分麵粉可以降低組合麵粉中直鏈澱粉含量，但會稀釋麵筋蛋白含量；而麵粉預糊化處理則會造成澱粉及麵筋蛋白性質改變。以上兩種原料處理方式皆會改變麵糰拉伸性質，造成饅頭外觀品質下降，經以RSM試驗設計法尋找出最適之配方組合，並依此進行加水量及活性麵筋添加量的適當調整後，饅頭外觀品質可提升至與100%麵粉所製之饅頭接近，甚至更佳。將以最適配方製得之饅頭分別於室溫、冷藏及冷凍-解凍循環條件下進行貯存試驗，結果顯示，饅頭硬度上升速率與澱粉回凝速率有相關性存在，並受貯存條件影響；此外，於室溫貯存期間，20%或30%麵粉預糊化處理之饅頭，即使無法檢測出澱粉回凝的現象、水分含量亦無明顯變化，其饅頭的硬度仍持續上升。以組合麵粉或部分預糊化麵粉製得之饅頭，其起始硬度及貯存後之最終硬度均低於100%麵粉所製得者。於室溫貯存下，降低直鏈澱粉含量及麵粉預糊化處理均能有效降低饅頭起始硬度及澱粉回凝速率，但在冷藏或冷凍-解凍循環貯存下，效果則較不顯著。其中，20%糯性米穀粉取代之組合麵粉或20%麵粉預糊化製得之饅頭其外觀品質與以100%麵粉製得者接近，且具有良好的貯存品質。而品評試驗結果指出，品評員對此二組饅頭之整體接受度皆顯著高於以100%麵粉製得之饅頭，除此之外，此二組饅頭即使於室溫貯存一天，品評員對其接受度仍相同於、甚至優於以100%麵粉製得之新鮮饅頭。由此可知，只要將配方做適當之調整，以糯性米穀粉取代部分麵粉或將部分麵粉預糊化之方式製備饅頭，皆能顯著提高饅頭外觀及其貯存品質。

關鍵字

預糊化 ； 回凝 ； 老化 ； 糯性米穀粉 ； 饅頭

並列摘要

There are two major parts of this study. In the first part, the composite flour, a mixture of waxy rice flour and wheat flour was used for steam bread making and the effects of waxy rice flour on the properties of dough and steam bread were investigated. In the second part, some wheat flour was pregelatinized before the sponge dough prepared and the effect on pregelatinized wheat flour on the properties of dough and steam bread were investigated. The amounts of wheat flour substituted by waxy rice flour in the composite flour and the ratio of pregelatinized wheat flour used were 10%、20% and 30%. The substitution of waxy rice flour in composite flour reduced in reducing its amylose content, and diluting its gluten content. The changes of pasting and gluten properties of dough, which was prepared with some of pregelatinized wheat flour, were observed. The changes of compositions of flour and pregelatinization treatment resulted in the significant changes of extensibility of dough, furthermore, the appearance and storage quality of steam bread was undesirable. The optimal formulations were able to produce the good appearance and storage quality of steam bread by adjusting the water absorption and vital gluten addition according to the results of the RSM experimental design. The steam breads made by the optimal formulations were then stored under three conditions (i.e. room temperature, refrigeration and freeze-thaw cycle) and the moisture content, hardness and enthalpy of steam bread crumb were determined during the storage periods. The results showed that the hardness of steam bread increased with increasing storage time in all three storage conditions, but with different rates. The moisture content of steam breads were different because the formulations but the moisture content did not change in each steam bread during storage. The retrogradation rate of starch was influenced by the formulation and storage condition. That is, the steam bread made with high water absorption was soft at fresh, but the degree of retrogradation during storage varied after storage. The steam bread made with 20% or 30% pregelatinized wheat flour before sponge preparation, no starch retrogradation was observed by the DSC determination although the hardness of crumb increased under the storage at room temperature. The steam bread made with the optimal formulations for composite flour (wheat:waxy rice＝8:2) and 20% pregelatinized wheat flour had the great acceptability when evaluated by sensory tests. The steam bread made with composite flour (wheat:waxy rice＝8:2) maintained the softer crumb texture after 1 day storage at room temperature than the steam bread made with 100% wheat flour. Such conclusion can be made that the proper adjustments of formulation is the requirements to make good appearance, eating and storage qualities of steam bread when waxy rice flour or pregelatinized wheat flour was applied. The waxy rice flour and pregelatinized wheat flour did improve the storage quality of steam bread stored at room temperature, which was attributed majority to the high moisture content of steam bread and/or to the weak starch gelation strength due to reduce the amylose content in composite flour.

並列關鍵字

staling ； retrogradation ； pregelatinization ； steam bread ； waxy rice flour

參考文獻

AACC. 2000. Approved Method of the American Association of Cereal Chemist. 10th ed. Minnesota:AACC.

Bhattacharya M, Erazo-Castrej SV, Doehlert DC and McMullen MS. 2001. Staling of bread as affected by waxy wheat flour blends. Cereal chem. 79:178-182.

Biliaderis CG, Page CM, Maurice TJ and Juliano BO. 1986. Thermal characterization of rice starches : a polymeric approach to phase transitions of granular starch. J. Agric. Food Chem. 34:6-14.

Cisneros-Zevallos L, Saltveit ME and Krochta JM. 1997. Hydroscopic coatings control surface white discoloration of peeled (minimally processed) carrots during storage. J. Food Sci. 62:363-366.

Collado LS and Corke H. 1999. Heat-moisture treatment effects on sweetpotato starches differing in amylose content. Food Chem. 65:339-346.