後熟作用與厭氧發酵對三種栽培諾麗果機能性成分及生物活性之影響

Abstract

諾麗即檄樹，學名為Morinda citrifolia L.，為常綠小喬木或灌木，果實未成熟時呈綠色，熟成後呈黃色或乳白色，果肉軟且具有異味。生長分布於大溪地、印度尼西亞、臺灣等南太平洋群島及東南亞地區。 在臺灣作為經濟栽培之諾麗主要有印尼種、臺灣種及大溪地種三種。研究已知諾麗果實具有抗氧化、抗菌、抗發炎、抗癌、調節血糖、保肝等生物活性。然此類研究多取材於諾麗發酵果汁，對諾麗果本身之研究反較缺乏。因此，本研究將臺灣現有栽培經後熟或不經後熟之諾麗果實，用水或乙醇溶液萃取後，測定諾麗果實生物活性，利用厭氧發酵果汁作為對照參考，調查其功能性成分含量、抗氧化活性、抗菌活性及對肝細胞的毒性。此外，並探討後熟與厭氧發酵，對諾麗果機能性成分含量及生物活性之影響。 由機能性成分分析結果可知，後熟作用能提高諾麗果酚類化合物及東茛菪素(scopoletin)等機能性成分含量，亦會降低類黃酮含量。如使用80%乙醇萃取之諾麗果，後熟作用會使總酚含量由8.28 mg GAE/g ~ 10.76 mg GAE/g上升到14.83 mg GAE/g ~ 17.65 mg GAE/g；東茛菪素含量由136.70 μg/g ~ 217.58 μg/g上升至356.87 μg/g ~ 1696.88 μg/g；總黃酮類含量則由2.42 mg QE/g ~3.85 mg QE/g下降至0.88 mg QE/g ~ 2.09 mg QE/g。此外，厭氧發酵作用亦能使總酚含量顯著提升至25.96 mg GAE/g ~ 34.83 mg GAE/g。由抗氧化力實驗中可發現，諾麗抗氧化之有效成分主要為醇溶性物質。後熟作用能提高ABTS自由基清除率、FRAP還原力等抗氧化能力。抗菌實驗中則發現，未後熟果對轉糖鏈球菌的抗菌活性佳，且具抑制生物膜形成之能力；發酵作用則有助於提升諾麗果對大腸桿菌之抗菌力。 本文可知臺灣三栽培種諾麗果的抗氧化活性、抗菌活性及抑制細菌生物膜形成之能力，具有開發成抗氧化、抗菌商品之潛力，期望將來能應用於保健食品中。

Noni (Morinda citrifolia L.) is a small evergreen tree or shrub, native to Pacific islands and Southeast Asia, such as Tahiti, Indonesia and Taiwan, while the unripen fruit is green, hard and odorless. After ripening, color of fruit will change to yellow or pale creamy white with soft flesh and pungent odor. In Taiwan, the three major cultivated noni are described as Indonesia, Taiwan and Tahiti. Researches of noni fruit concern antioxidant, anti-bacterial, anti-inflammatory, anti-cancer, regulating blood sugar, hepatoprotective, and other biological activity. However, their results are major from fermented juice, and seldom from fruit itself. Therefore, this study prepared water or ethanol extraction of fruit, and tested their biological activity, using noni fermented juice as a cross-reference, then investigated the functional components, antioxidant activity, antimicrobial activity and toxicity of the liver cells. In addition, the effects of ripening and anaerobic fermentation on functional components and bioactivity of noni fruits are explored. According to the functional component analysis, the ripening can enhance noni production of phenolic compounds and scopoletin, but some components reduced, such as flavonoids. For example, after ripening, the content of total phenolics and scopoletin of 80% ethanol extract from noni fruit would rise from 8.28 - 10.76 mg GAE / g to 14.83 - 17.65 mg GAE / g and 136.70 - 217.58 μg / g to 356.87 - 1696.88 μg / g, respectively. And total flavonoid content decreased from 2.42 mg - 3.85 mg QE / g to 0.88 - 2.09 mg QE / g. Anaerobic fermentation also makes the total phenolics increased significantly to 25.96 mg GAE / g - 34.83 mg GAE / g. By the results of antioxidant activity test, the main active ingredients of noni antioxidant are alcohol-soluble substances. Ripening can improve ABTS radical scavenging and FRAP reducing power. Anti-bacterial activity of unripen noni fruit is good for Streptococcus mutans in an anti-bacterial test and in inhibition test of biofilm formation. The fermentation process of noni contributes to anti-bacterial activity against Escherichia coli. The antioxidant activity, anti-bacterial activity and inhibition of biofilm formation of three noni fruits cultivated in Taiwan shows the potential for antioxidant and anti-bacterial product in this study. We expect some product of noni fruit in Taiwan can be applied in health food business in the future.