檄樹（諾麗）果實自然發酵過程中果汁與乾燥果肉所含 酚類化合物之變化

Abstract

檄樹 (Morinda citrifolia L.) 也稱為諾麗 (noni)，原產於東南亞至澳洲一帶，主要加工產品為諾麗果汁，但果汁發酵時間各家不同，未有統一的製程。故本實驗以酚類化合物含量變化為評估基準，作為建立諾麗果最佳發酵時間的依據，並比較諾麗果發酵期間離心汁與自流汁，以及冷凍乾燥和熱風乾燥所得諾麗果肉粉末成分的差異。實驗結果顯示，諾麗果汁的總榨汁率隨發酵時間由25% (unripe) 增加至53% (第168天)；總酚與類黃酮含量則隨發酵時間延長而降低 (總酚由1.6mg/mL降至1.0mg/mL gallic acid (GA) equivalent左右，類黃酮則由37.5μg/mL降至約6.0μg/mL quercetin equivalent)；果汁中縮合單寧含量在第2週時達到0.23mg/mL catechin equivalent之最高量，且離心汁與自流汁之間差異不大。冷凍乾燥果肉研磨之粉末經50倍之甲醇萃取後之總酚含量，較熱風乾燥之樣品高，水萃取部分則沒有明顯差異，其中發酵初期以甲醇萃取之果肉粉末約在10.9mg/g GA equivalent，隨發酵時間下降至6.0mg/g GA equivalent，而甲醇萃取之熱風乾燥粉末則穩定維持在5.5-6.0mg/g equivalent；水萃取之熱風乾燥粉末類黃酮含量較冷凍乾燥處理者多，由356μg/g隨發酵時間下降至24週時約179μg/g quercetin equivalent；甲醇及水萃取粉末之縮合單寧含量隨發酵時間增長而降低。整體來說，冷凍乾燥處理之粉末較熱風乾燥處理者稍佳。以HPLC分析樣品中rutin、scopoletin及quercetin含量，隨發酵時間延長，果汁樣品rutin由42μg/mL降至0；scopoletin由56μg/mL降至27μg/mL；quercetin含量較少，最多只有1.84μg/mL。甲醇萃取之冷凍乾燥粉末所含這3種成分均較熱風乾燥為佳，含量變化則相似，除quercetin隨時間而增加外，rutin及scopoletin皆隨發酵時間而下降，可能由於發酵過程rutin降解為quercetin所致。此外，甲醇萃取之果肉粉末三種機能性成分含量均較果汁中含量高數倍。整體而論，諾麗果發酵時間以2-4週為宜，且諾麗果榨汁後果肉脫水製成之粉末中亦含機能性成分，可進一步加工利用。

Morinda citrifolia L., also called “noni”, is native from Southeast Asia to Australia. The main product is noni juice, but the fermentation time and procedure for making juice are different from manufacturers and yet to be optimized. This study attempts to establish the best fermentation time for noni fruit, based on the changes of phenolic compounds, the components difference between centrifugal juice and free run juice, and noni pulp powder made from freeze dried and hot air dried during fermentation. The results show that total juice yield is increasing from 25% (unripe) to 53% (day 168) during fermentation. Total phenols and flavonoids are decreasing with fermentation (1.6mg/mL down to 1.0mg/mL gallic acid (GA) equivalent, 37.5μg/mL down to 6.0μg/mL quercetin equivalent, respectively). Condensed tannins attain maximum value 0.23mg/mL catechin equivalent on the second week, and the difference between centrifugal juice and free run juice are not significant. Pulp powder extractes (with 100% methanol extraction ratio to powder of 50:1) have better yield from freeze dried is better than hot-air dried in total phenols. The samples extracted with H2O are not significant difference from freeze dried methanol extract. On the early fermentation period, the total phenols of pulp powder that is extracted with methanol is about 10.9mg/g GA equivalent and is decreasing to 6.0mg/g during fermentation. The hot-air dried powder is stable at 5.5-6.0mg/g GA equivalent. However, hot-air dried pulp powder extracted with H2O has more flavonoids than freeze-dried pulp powder, and its content is decreasing from 356μg/g to 179μg/g (24 weeks) quercetin equivalent. The condensed tannins, both from pulp powder extracted with methanol and H2O are decreasing with fermentation. The freeze-dried extract is a little better than hot-air dried in general. The rutin, scopoletin and quercetin in noni juice are quantitated by HPLC. Results show that rutin and scopoletin are decreasing from 42μg/mL to 0 and 56μg/mL to 27μg/mL respectively. And the contents of quercetin presents much less than others, maximum value is 1.84μg/mL. Freeze-dried pulp powder extracted with methanol is better than hot-air dried pulp powder on these three compounds, however, the changes are similar. Except for quercetin, rutin and scopoletin are decreasing with fermentation, and perhaps because rutin degrades into quercetin. Moreover, pulp powder extracted with methanol have more three functional compounds times than the juice. In whole, 2-4 weeks is the best noni fermentation time. And the noni pulp powder made from juice residual presents many functional components, it worths further study and utilization.