採收後毛豆預冷之研究

Abstract

毛豆莢之色澤是決定其商品價值之重要要因素。採收後之毛豆莢極易快速黃化，因此有待研究預冷處理方法對不同毛豆莢減緩黃化之方法，以確保毛豆莢之翠綠色澤。試驗之預冷處理有噴水、浸地下水、浸15℃冷水、浸5℃冰水、置於冷藏庫中冷卻、以及對照等5種；供試之品種則有高雄選1號、205、綠光等。由試驗結果顯示未經預冷處理之毛豆，其莢果極易黃化，且亮度之變化較少。經噴水及浸地下水之處理者，其降低毛豆莢黃化之效果較差，莢果經7小時後，黃化程度就會明顯提高。而浸5℃冰水、浸15℃冷水及冷藏處理者，採收後7小時後之莢果色澤不易變黃，亮度之變化較顯著，防止毛豆莢果黃化之效果最佳。因此，在實用及經濟上，減緩毛豆莢黃化之預冷當以浸15℃冷水之處理為最優。 The commercial quality of vegetable soybean was mainly determined by the pod color. Yellowing of pods occurred rapidly after the harvest of vegetable soybean. Hence, studies on the pre-cooling treatment of pods for preservation of bright green color and preventing the yellowing of pod before freezing processing was required. Pre-cooling treatments tested in this experiment were spraying pods with tap water, drenching pods in 15℃ cold water, drenching pods in 5℃ cold water, storing pods in refrigerator, and the control. Vegetable soybean varieties used were Kaohsiung Selection 1,205 and Ryokkoh. Results showed that pod color was easily changed to yellow dramatically and L value was unchanged for the non-treated pods. After 7 hours, treatments of spraying water on pods and drenching pods into tap water can slightly prevent the yellowing of pods. Best pre-cooling effects of pods drenched in 15℃ and 5℃ cold water and stored by refrigerator were found. The bright green color in pods can be maintained and yellowing of pods can be prevented longer than 7 hours and the L values can be reduced by above-mentioned methods. For practical and economical purposes, the best pre-cooling treatment for preventing the yellowing of vegetable soybean pods is by drenching pods into 15℃ cold water after pod threshing and harvesting.