酸鹼處理對發芽糙米理化特性之影響及其加工應用

發芽糙米(Germinated brown rice, GBR)為糙米浸泡於水中使其發芽製備而成。在萌發期間，水解酶會被活化，分解澱粉、纖維和蛋白質。此外，萌發過程中會產生各種促進健康的活性化合物，與原生糙米相比，發芽糙米含有更多的維生素、礦物質、纖維和植物化學物質，如植酸，阿魏酸，γ-谷維素和在神經傳遞中具有重要作用的γ-氨基丁酸(Gamma-Amino Butyric Acid, GABA)。因此，發芽糙米常被推薦食用。但由於發芽糙米其質地類似於糙米，不易煮熟且口感較硬，食用上不受歡迎，接受度不佳。為提高發芽糙米的食用率，本研究探討酸鹼處理之發芽糙米其理化特性變化，實驗結果顯示，若糙米經過鹼處理，其發芽率隨著處理時時間長短會有下降的趨勢，此趨勢可經由添加植物激素進行改良，在質地分析上經酸鹼處理之發芽糙米組別在硬度上均有明顯的下降，其中以鹼處理的發芽糙米具較好的表現(27.06 N)，膠質性則以酸處理之組別整體表現較佳(2.17 N)。根據掃描式電子顯微鏡(SEM)觀察結果，酸鹼處理後，表面均有明顯侵蝕軟化之裂痕，以鹼處理最為明顯，酸處理在斷面有較小澱粉顆粒。而經過酸鹼處理後，直鏈澱粉含量均較一般發芽糙米增加，在抗性澱粉上以酸處理的組別增加顯著(6.21%)，而生物活性成分GABA含量鹼處理之發芽糙米與一般發芽糙米含量無顯著差異，而酸處理的部份有明顯的表現量(66.95 mg)。本實驗顯示，酸鹼處理後對發芽糙米質地有軟化的效果以鹼處理效果最明顯，並顯示酸處理的加工方式可增加GABA、直鏈澱粉與抗性澱粉之表現，並在發芽過程中抑制微生物生長具有一定效果。

關鍵字

發芽；糙米； γ-氨基丁酸(GABA) ；酸鹼值；直鏈澱粉；抗性澱粉；質地分析

並列摘要

Germinated brown rice (GBR) is produced by steeping the brown rice grains in water and allowing them to bud. During germination, hydrolytic enzymes activate, breaking down starch, fibers and proteins. Moreover, germination generates various bioactive compounds of health-promoting activities through the enzymatic actions. Compared to native brown rice, GBR contains more vitamins, minerals, fibers, and phytochemicals such as phytic acid, ferulic acid, gamma-oryzanol and gamma-amino butyric acid (GABA), which has a significant role in neurotransmission. Therefore, the GBR has been suggested to be utilized as a healthy ingredient in a variety of foods. In spite of these benefits, GBR is under-utilized due to its poor cooking properties. It similar to brown rice, is difficult to cook and gives unfavorably hard texture of cooked rice. Of this study was to explore the germination of acid and alkali treatment of its physicochemical properties, the experiment results show that if the brown rice after alkali treatment, its germination rate decreasese with soaking time, and the trend can be improved by adding gibberellic acid. On the texture analysis, acid-alkali treatment on the hardness of the germinated brown rice group have obvious reduce,which with alkali treatment bester performance (27.06 N), gummines with acid treatment had better performance (2.17 N). According to Scanning Electron Microscope (SEM), after the acid-alkali treatment, the surface has the obvious erosion softening of crack, and the alkali treatment is obviously, besides the section with small starch kernel in acid treatment. After the acid-alkali treatment, the amylose content increased compared with the normal germinated brown rice, and the acid treatment of GBR on the resistant starch increased significantly (6.21%), the GBR and alkali treatment of GBR of the bioactive compound GABA was no significant difference, in addition, there was a significant expression (66.95 mg) after acid treatment. The experiment showed that the acid-alkali treatment can soften the GBR texture, after alkali treatment are most in evidence, and the processing by acid treatment can increase the value of GABA, amylose and resistant starch, and inhibit the microbial growth in germinated processing.