依脂氧化酶活性及其異構酵素型態探討冷凍毛豆適宜的加工品種及採收時間

SELECTION OF SUITABLE VARIETY AND HARVESTING TIME FOR FROZEN VEGETABLE SOYBEANS BASED ON LIPOXYGENASE ISOZYME PATTERNS

毛豆為臺灣重要的泠凍蔬葉之一，本研究室已探討出脂氧化酶（Iipoxygenase）應較過氧化酶（peroxidase）為毛豆適宜的殺菁指標，因此以臺灣三個主要毛豆品種（#205，綠光和高雄選一號即AGS292）為材料，觀察生長期間一般成份、脂氧化酶活性和異構酵素之變化，以找出其最適宜之加工品種及採收時間。三個品種毛豆生長期間一般成份變化相似，脂氧化酶活性均隨生長漸增，而以高雄選一號活性最低及綠光品種最高，三個品種毛豆在毛豆期均只含二種脂氧化酶異構酵素（L-1 & L-2），而到達黃豆期前，只有#205及綠光品種出現第三種脂氧化酶異構酵素（L-3），基於一般成份分析、脂氧化酶活性和異構酵素出現型態的觀點，高雄選一號應為較適宜之泠凍加工毛豆品種，而毛豆期前後共一星期間為最適宜之採收時間。

Vegetable soybeans are one of the most important frozen vegetables in Taiwan. Our previous studies showed that lipoxygenase (LIP) was more suitable than peroxidase as the blanching index for frozen vegetable soybeans. For choosing the best vegetable soybean variety among three major varieties ('#205', 'Ryokkoh' and 'AGS 292') in Taiwan and the harvesting time, LIP activity and LIP isozyme patterns for the three varieties of vegetable soybeans during growth were investigated. And their proximate compositions during growth were also determined. The changes in proximate compositions of these three vegetable soybean varieties were similar during growth. Their LIP activities increased with growth. 'AGS 292' had the lowest LIP activity, while 'Ryokkoh' had the highest LIP activity. The three varieties had only two LIP isozymes (L-1 & L-2) at the vegetable soybean stage. Varieties '#205' and 'Ryokkoh' had the third UP isozyme (L-3) before soybean maturation, but 'AGS 292' did not have it even at fully mature stage. Based on the LIP activity, LIP isozyme patterns and proximate composition, we suggested that 'AGS 292' was the most suitable vegetable soybean variety for freezing and the period between one week before and after the vegetable soybean stage of growth was the most suitable harvesting time.