不同預冷方法對葉菜類的品質及保鮮期之影響

Abstract

葉菜類採收後，在25℃高溫時，呼吸率高，小白菜達l03 mg CO2/kg • hr，韭菜達471.4 mg CO2/kg • hr；以不同預冷方法，使降溫到5℃，水冷需5~6分鐘，強風壓差預冷需20~25分鐘，真空預冷需4~5分鐘，預冷後，以塑膠袋包裝，貯藏於5℃，可以保存良好品質，且可貯藏約6天，若貯於20℃，貯藏壽命則仍短，品質下降快。預冷者之葉色、全糖含量，纖維含量顯示比不做預冷處理的品質保存效果好。 蔬菜採收後應盡量減少受傷，再做預冷處理，對品質及保鮮期會有好的效果；韭菜適合以強風壓差預冷或真空預冷，不適以水冷。小白菜以三種預冷方法均可，視運輸距離及設備費用而定，近郊葉菜類，以水冷及強風壓差預冷較經濟。 The respiratory rate of some leafy vegetables is high at 25℃, with 103mg CO2/kg.hr for Pak-choi and 471.4 mg CO2/kg.hr for Chinese leek. The time required to cool down to 5℃ by different cooling method are : 5~6 minutes by hydrocooling, 20~25 minutes by forced air cooling and 4~5 minutes by vacuum cooling. By packaging with plastic film and stored under 5℃ after precooling, the vegetables could be kept in good quality for 6 days. The storage period will be shortened and the quality will be changed if they were stored at 20℃. The precooled vegetables had better overall quality, higher total sugar content and lower fiber content than that of the non -precooled control. Precooling treatment could keep the vegetables in good quality and prolong its storage period. Both vacuum cooling and forced air cooling are suitable for Chinese leek, however hydrocooling is not suitable. All the three methods are suitable for Pak-choi. For suburb leafy vegetables, both hydrocooling and forced air cooling are suitable, the choice depends on the distance of transportation and the cost of feasility.