| 摘要: | 糙米為稻米去殼後之產物，與脫殼脫糠之白米相比，保留了較多的營養素，故營養價值較高。將糙米發芽後稱為發芽糙米，與糙米相比，發芽的過程中會累積更多營養素，而且口感較糙米柔軟。經過納豆菌發酵後可以產生納豆激酶，此酵素具有溶解纖維蛋白的能力。本研究以台南11號發芽糙米、糙米，以及將糙米脫糠後的白米為樣品，接種納豆菌(Bacillus natto)，於37℃、95 % RH條件下，以150 rpm之迴轉式振盪器進行 60小時培養，分析發酵前後，其一般成分(水分、粗灰分、粗脂肪、粗蛋白)與機能性特性(米糠醇、GABA及游離胺基酸含量、納豆激酶、DPPH自由基清除能力)之變化，目的是期望以糙米或發芽糙米為原料，發酵為手段發展成稻米加工產品之可行性，並探討其機能性。研究結果顯示，經過納豆菌發酵後，稻米樣品中粗灰分與粗脂肪上升，粗蛋白含量降低。總游離胺基酸在發芽糙米及白米是顯著增加。三種米樣品之必需胺基酸總含量皆上升。發酵後之GABA含量(mg/100g DM)呈現下降，其程度在發芽糙米約10%、糙米29 %、白米55 %。發酵後發芽糙米之米糠醇(mg/100g DM)降低約48 %、糙米為56 %、白米為29 %，而DPPH自由基清除率明顯提升，(糙米36.95→ 83.94 %，發芽糙米30.80→83.24 %，白米11.31→86.04 %)，推測因微生物的生化作用而產生其他具有較高抗氧化力的成分。發酵後產生之納豆激酶活性(FU/g)以發芽糙米最高(43.11)，其次為糙米(19.62)，白米最低(12.24)。綜合研究結果顯示在三種米型態中，以納豆菌發酵發芽糙米可增加其製品的營養價值與機能特性，未來研究可針對不同活性及機能性成分來擴大探討納豆菌發酵發芽糙米之最適生長條件。
Brown rice (BR) is a product generated during the process of grain husking, and rich in nutrients, so brown rice has higher nutritive value than refined white rice (WR). Germinated brown rice (GBR) is different from usual brown rice in that it has undergone the process of germination. Compare with BR, the properties of GBR are that the nutritive value is largely raised and texture is tenderer due to germinating. Recent research has shown that nattokinase with fibrinolytic properties is produced after fermented with Bacillus natto. Therefore, the whole grain rice (BR and BGR) were used as the ingredients and were fermented with Bacillus natto in order to develop a functional fermented rice grain product in this study. Tainan 11 variety was selected and three rice types (GBR, BR and WR) were fermented with Bacillus natto at 37℃ for 60hrs. Those rice samples were analyzed for the content of chemical composition (moisture, crude ash, crude lipid, crude protein) and functional properties (γ-oryzanol, GABA, free amino acids, nattokinase, DPPH racdical scavenging). The results have shown that the contents of crude ash and crude fat increased, however, crude protein decreased after fermentation. The contents of total free amino acids in the fermented GBR and WR were significant increases. The total essential amino acids contents of three fermented rice samples increased. And all the fermented samples of GABA contents (mg/100g DM) were reduced: 10 % in GBR, 29 % in BR and 55 % in WR. Also, the γ-oryzanol content (mg/100g DM) decreased after fermentation: 48 % in GBR, 56 % in BR and 29 % in WR. The DPPH radical scavenging of the samples increased after fermentatioin (BR 36.95 %→83.94 %, GBR 30.80 %→ 83.24 %, and WR 11.31 %→86.04 %) and it is suggusted that because of the biochemical metabolism of microorganisms, other more antioxidative components were produced. The fermented GBR possessed the highest activity of nattokinase (43.11 FU/g), followed by BR (19.62 FU/g) and WR (12.24 FU/g). The results indicated that it was a benefit of nutritive value and functional properties from combination of GBR and fermentation with Bacillus natto. Future studies could be aimed at establishment of the optimal conditions for functional propertitis and sensory quality of fermented germinated brown rice. |
