高壓技術與其他富化處理提升豆科種子中γ-胺基丁酸含量之研究

Abstract

γ-胺基丁酸 (gamma-aminobutyric acid, GABA)，普遍存在於動、植物體內，是重要的四碳游離胺基酸。藉由攝取 GABA 可降血壓、抗憂鬱、減緩疼痛與舒緩焦慮。一般高等植物組織中GABA含量低，約0.3 - 20 mg/100g，但使用GABA富化技術能在短時間內促進GABA的累積。本研究以高壓 (High pressure process, HPP) 處理高蛋白質含量之豆科種子與豆仁，提高其GABA含量，並與其他處理比較，找出最適GABA富化條件。以 PITC (phenylisothiocyanate) 試劑衍生化GABA建立分析方法，五重複檢測值之R.S.D為4.83%，樣品添加0.938 mg GABA衍生化後回收率為105.25%，標準曲線線性RSQ值為0.9994，確立檢測方法後進行各種處理之分析。在不影響豆科種子加工應用狀況下，紅豆以浸水12小時獲得最高GABA含量20.99 ± 5.19 mg/100g，為對照組的四倍；黃豆、黑豆浸泡22小時後高壓處理靜置0.5天和四天，綠豆浸泡4小時後高壓處理靜置四天，可提升最多GABA累積，分別為60.34 ± 1.01、70.15 ± 2.34與136.12 ± 6.56 mg/100g，相較對照組增加約8.5至41倍。新鮮毛豆仁、豌豆仁、皇帝豆與帶殼毛豆經相同高壓條件處理後靜置0.5天，GABA含量增加至248.81 ± 44.30、173.97±6.54、121.92 ± 19.01、431.95 ± 20.42 mg/100g，提升二至七倍。高壓處理促進黃豆中GmGAD1, GmGAD2, GmGAD4, GmGAD5的表現量，顯示高壓處理增加豆科種子與新鮮豆仁中GABA含量，可能與促進GmGAD mRNA的表現量、合成新的GAD蛋白質有關。各種豆科種子與豆仁最適富化處理不同，依照不同作物選取合適的處理方法，可以方便、簡單獲得健康的食品原料。

γ-aminobutyric acid, also known as GABA, is an important four-carbon free amino acid to both plants and animals. GABA is widely found in human central nervous system. By consumption of GABA-enriched food, people can get the benefit of decreasing blood pressure and inhibition of neurotransmitters in the central nervous system to decrease pain and anxiety. In this study, GABA contents in legume seeds were increased by using different enrichment treatments, including soaking, germination and high pressure processing. After the treatments, amino acids extracted from seeds were derived with phenylisothiocyanate (PITC) and analyzed by high performance liquid chromatography. The main idea aims at finding out the best treatment for the highest GABA contents in red beans, soybeans, black beans, mung beans, green soybeans, peas and lima beans. Red beans, black beans and soybeans reached the highest GABA contents after germination six days which are 37.21 ± 1.82, 93.29 ± 4.15 and 292.79 ± 2.96 mg/100g (7.2 to 155 times as the control). Soybeans soaked in water for 22 hours and high pressure processed gained 60.34 ± 1.01 mg/100g GABA contents within the first standing day. Mung beans soaked in water for 4 hours and high pressure processed displayed 136.12 ± 6.56 mg/100g GABA contents on the fourth standing day. Even though the GABA contents of HPP-green soybeans, peas and lima beans increased significantly, the fresh beans resulted bad smell and appearance after the first standing day. Besides, the expression of GmGAD1, GmGAD2, GmGAD4, GmGAD5 of HPP-soybean indicated that high pressure induced GAD mRNA expression and possibly facilitate GAD synthesis. In conclusion, by using proper GABA-enriched treatment would significantly increase GABA contents in red beans, soybeans, black beans, mung beans, green soybeans, peas and lima beans.