提升百香果殼中γ-胺基丁酸含量之研究

百香果 (Passiflora edulis)，為熱帶美洲的一種本土植物，常種植於熱帶或亞熱帶氣候區，人們通常取之內部種子與內果皮作食用，但食用後留下的大量果殼對於環境會造成影響。γ-胺基丁酸 (Gamma-aminobutyric acid, GABA)，為哺乳動物中樞神經系統中，最主要的抑制性神經傳導物質，可調控食慾以及調節免疫，同時具有抗憂鬱和抗焦慮之功效。許多研究發現，以逆境給予植物壓力，能使GABA生成量大幅增加，本研究使用百香果殼「台農1號」進行缺氧逆境處理，提升其GABA含量。將百香果殼進行真空處理、真空後填充CO2處理以及真空後填充N2處理，三者在不同時間點皆能提升GABA之含量，並以真空處理靜置4天之百香果殼有最高含量之GABA含量。逆境處理改以40℃作為風乾百香果殼之溫度，較以20℃及60℃有更高的GABA含量，另外，考量經濟效益及方便性，續以真空處理進行試驗，並探討百香果殼在經過真空處理下不同貯藏天數其GABA變化與其生化作用機制。以未真空處理百香果殼並於冷藏靜置3天會顯著生成1683.36±143.36 mg·100 g-1之GABA，與Control組相比提升28.80%；以真空處理百香果殼並於冷藏靜置4天會顯著生成更高的GABA含量，可達2139.25±26.69 mg·100 g-1，與Control組相比提升63.68%。經過未真空處理及真空處理後，Glutamic acid含量分別下降40.49%及66.70%，GAD活性也同樣於第3天 (0.0233±0.0040 U·mg-1) 及第4天 (0.1351±0.0025 U·mg-1) 有高活性。使GABA含量下降可能是由於GABA-T之作用，未真空處理及真空處理之GABA-T (Ala) 及GABA (Glu) 活性皆會從第1天上升至第5天，另外，未真空處理及真空處理之多胺含量，會於GABA含量生成最多的前一天 (即第2天及第3天) 有最多的多胺含量，而氧化多胺形成GABA的DAO酵素則分別在第3天 (0.0005 U·mg-1) 及第4天 (0.0037 U·mg-1) 有最高的活性。在本研究中，未真空處理組主要透過DAO氧化多胺生成GABA，而真空處理組除了透過DAO作用外，同時也透過GAD轉化Glutamic acid生成GABA。總結所述，真空處理具有提高百香果殼中GABA含量之效果，進而成為具有機能性之水果副產物，期望能提供百香果殼副產物更多利用價值。

關鍵字

百香果殼； γ-胺基丁酸；真空處理；麩胺酸脫羧酶；二胺氧化酶

並列摘要

Passion fruit (Passiflora edulis), a native plant in tropical America, is often planted in tropical or subtropical climates. People usually take the inner seeds and endocarp for food, but the large amount of husk left after eating will affect the environment. Gamma-aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the central nervous system of mammals. It can regulate appetite and regulate immunity, as well as anti-depression and anti-anxiety effects. Many studies have found that stressing plants under adversity can greatly increase GABA production. In this study, passion fruit "Tainong No. 1" was used for anaerobic stress treatment to increase its GABA content. Using 40℃ as the temperature for drying passion fruit peels has a higher GABA content than 20℃ and 60℃. In addition, the passion fruit is subjected to vacuum treatment, post-vacuum carbon dioxide treatment, and post-vacuum nitrogen treatment. The three are at different time points, the GABA content can be increased. Considering the economic benefits and convenience, the experiment was continued with vacuum treatment, and the biochemical mechanism of the passion fruit peel under vacuum treatment was discussed. Passion fruit peels are non-vacuum-treated and placed in cold storage for three days, which will significantly generate 1683.36±143.36 mg·100 g-1 of GABA, which is an increase of 28.80% compared with the control group. Passion fruit peels are vacuum-treated and placed in cold storage. After four days, it will produce significantly higher GABA content, which can reach 2139.25±26.69 mg·100 g-1, which is an increase of 63.68% compared with the control group. After non-vacuum treatment and vacuum treatment, the content of glutamic acid decreased by 40.49% and 66.70%, respectively. GAD activity was also the same on the third day (0.0233±0.0040 U·mg-1) and the fourth day (0.1351±0.0025 U·mg-1) has high activity. The decrease in GABA content may be due to the effect of GABA-T. The activities of GABA-T (Ala) and GABA (Glu) with non-vacuum treatment and vacuum treatment will increase from day 1 to day 5. In addition, with non-vacuum treatment and the polyamine content of the vacuum treatment will have the most polyamine content on the day before the maximum GABA content generation (i.e. the 2nd day and the 3rd day), while the DAO enzyme that oxidizes polyamine to form GABA will have the most polyamine content on the 3rd day (0.0005 U·mg-1) and the 4th day (0.0037 U·mg-1) have the highest activity. in this research, the non-vacuum treatment group mainly generates GABA through the oxidation of polyamines by DAO, while the vacuum treatment group also converts Glutamic acid to GABA through GAD in addition to the effect of DAO. In summary, the vacuum treatment has the effect of increasing the GABA content in the passion fruit peel, and then becomes a functional fruit by-product. It is hoped that it can provide a solution to the excess of passion fruit peel waste.