預冷與貯藏溫度對蘆筍嫩莖呼吸率、品質及保鮮之影響

Effects of Precooling and Storage Temperature on the Respiration, Quality and Shelf-Life of Asparagus Spears

蘆筍嫩莖，一旦離開母體因受採收後生理及生化之變化所影響，則發生內部纖維、木質素及酸分含量之增加，而全固形物、維生素丙及其有機物質之相對減少之現象。為了防止或抑制採收後蘆筍嫩莖之劣變，本研究採用水冷法，依照水冷圖標調節噴洒預冷頗收功效。經此水冷之嫩莖再以5°C、相對濕度之室內貯藏，其呼吸率較20°C 85%相對濕度者約降低四倍。其保鮮效果甚佳，綠蘆筍有三天，白蘆筍有一天之品質保持與採收當天者相近。但是冷凍白蘆筍之品質言，若以此處理與冷藏三天，則無法防止其中粗纖維及木質素之增加而老化。貯藏之溫度對嫩莖之色澤變化之影響較濕度為大。貯藏一天後，綠蘆筍之光亮度（L 值）及綠色（-b值）及白蘆筍之暗化程度受貯藏溫度之影響頗大。葉綠素之減退亦與貯藏於5°C時間成正相關，即貯藏剛開始之頭二天，蘆筍嫩莖基部之葉綠素消退較尖部為快，而以後則以近尖端部消退為快。

After being harvested the asparagus spears will increase its fiber content very rapidly accompanying with the physiological and biochemical changes at the room temperature within a few days. Results obtained from this experiment indicated that contents of total soluble solids, ascorbic acid, and other organic constituents decreased in the stored spears. In order to prevent or inhibit the quality lowering and deterioration of the postharvest asparagus spears caused by the environmental factors, a hydrocooling nomograph was applied. The spears were kept fresh and had a better shelf-life in the cold room under 5°C and 95% relative humidity for three days to the green asparagus while for one day to the white asparagus. However, for the freezing purpose, the above mentioned method could not be applied to the white asparagus due to the fact that more cellulose could bs converted into fiber and lignin very quickly and more roughness would present in the white spears as revealed in this study. The experiment also indicated that during stored under low temperature and high humidity conditions, a higher respiration rate revealed in the white asparagus spears than that in the green asparagus spears. The chlorophyll content in the green asparagus spears reduced obviously in the first two days in their batt part, but the reduction showed evident at the tip part in the following days.