發芽及熟化處理對國產豆類機能性成分之影響

Abstract

本研究針對國產的豆類，欲探討發芽及熟化的處理對其機能性成分以及澱粉消化性質的影響，藉此評估國產豆類品種用於保健食材的潛力。試驗結果發現，在9種國產豆類品種中，大豆以蛋白質所佔比例較高，而紅豆及綠豆以碳水化合物為主，且所有品種之膳食纖維皆約為20%。9種豆類品中中僅有6種品種可以發芽，且最多經過3天後發芽率便可達100%。具有色種皮的黑豆TN3及紅豆AKS8、AKS9的抗氧化特性最佳，且豆類在經由浸泡及發芽處理後，能顯著提升抗氧化特性，所有處理中，以GTN5發芽3天具有最佳的DPPH自由基清除率，這可能和其高維生素C含量有關。黃豆KS10及黑豆TN3之總大豆異黃酮及總配醣體含量皆以發芽3天最高；紅豆AKS8及AKS9在經過35°C、5小時浸泡過後，GABA含量便有很顯著的上升；綠豆GTN5及TS95-03M分別經過3及2天的發芽後可以得到最高的維生素C含量。大豆經過加熱處理後，異黃酮會有形式的轉變或者是降解的反應所進行，經乾熱處理有從malonylglucoside轉變成acetylglucoside及glucoside的趨勢；濕熱處理後，malonylglucoside雖也會大量降解，但僅glucoside顯著上升。黃豆KS10經由5小時浸泡後濕熱30分鐘後、黑豆TN3經由發芽3天後做210°C乾熱處理，可以保留最高的總大豆異黃酮及總配糖體含量。紅豆中的GABA耐熱穩定性高，經由濕熱處理並不會造成GABA含量顯著性的下降，但乾熱處理後紅豆的GABA則會下降至為處理前之20-30%。維生素C為熱敏感之物質，易受熱影響而破壞，但綠豆芽菜經過高溫短時間殺菁並凍乾後仍能維持60%之維生素C含量。成熟紅豆及綠豆之RS含量皆高達約50%以上且RDS均小於20%，以紅豆AKS8有最高的RS，綠豆GTN5有最低的RDS。乾熱處理後，RDS含量會有顯著的上升，且RS含量下降。在酵素處理中，若以SDS及RS為生產指標，則以40-60 ASPU/g之酵素劑量、12-24 hr水解且於4°C回凝24小時為最佳條件。

The objective of this study was to investigate the effects of germination and heating treatments on the bioactive compounds and starch digestibility in domestic grown legumes, and to assess the potential of the using for healthy food ingredients. In 9 domestic legume varieties, protein was the major component in soybeans, and carbohydrates in azuki beans and mung beans. All varieties composed about 20% dietary fiber. Only 6 of 9 domestic legume varieties could germinate, and all of the 6 varieties germinated completely in 3 days. The dark-coat seeds, black soybean TN3, and azuki bean AKS8 and AKS9 had the highest antioxidant properties. After soaking and germination, antioxidant properties of legumes could significantly improved. In all treatments, the 3-day’s germinated mung bean GTN5 had the best DPPH scavenging abilities, this could be related to the high vitamin C content in mung bean. Soybean KS10 and black soybean TN3 had the highest contents of total isoflavones and total aglycones after 3-day’s germination. After soaking, GABA contents in azuki bean AKS8 and AKS9 had significantly increased. Vitamin C contents in mung bean GTN5 and TS95-03M reached the highest after germinated 3 and 2 days, respectively. During heat process, isoflavones in soybeans might be converted to another form or degraded. The malonylglucosides decreased dramatically corresponding with the increases of glucosides and acetylglucosides after dry-heating treatments, but only increased of glucosides after moist-heating treatments. Soybean KS10 remained the highest contents of total isoflavones and aglycones after soaking and 30-min moist-heating treatment, while black soybean TN3 had the highest contents of total isoflavones and aglycones after 3-day’s germination and 210°C dry-heating treatment. GABA in azuki beans was thermal stable, and they wouldn’t decreased after moist-heating treatments. But in dry-heating treatments, GABA decreased to about 20-30% of the non-treated sample. Vitamin C was a heat-sensitive compound, and it would be decomposed by heat treatments. Applying the blanching treatment (100℃/10 sec) before freeze-drying, there was still 60% of vitamin C left compared to non-blanching samples. RS contents were higher than 50 % and RDS contents were lower than 20 % in all matured azuki beans and mung beans. Dry-heating raised the percentages of rapid digestible starch (RDS) in azuki and mung beans, while decreased the percentage of resistant starch (RS). For the purpose of production of SDS and RS, the best enzyme hydrolysis condition was 40-60 ASPU/g enzyme dosages, 12-24 hr hydrolyzation time, and 24 hr retrogradation.