Postharvest Responses of Chinese Cabbage to High CO2 Treatment or Low O2 Storage1

Abstract

Abstract The outer leaf laminae of Chinese cabbage (Brassica campestris L Pekinensis group) contain higher amounts of ascorbic acid than the outer midribs, inner leaf laminae, or inner midribs. However, the outer leaf laminae lost ascorbic acid at a faster rate than other parts of the Chinese cabbage during storage at 0°C. Quantitative differences in sugars were also found in different parts of the Chinese cabbage. The outer leaf laminae were low in total sugars and had higher amounts of fructose than glucose, whereas outer midribs contained much higher amounts of glucose than fructose. The inner leaf laminae were high in both fructose and glucose and had a higher ratio of glucose to fructose. A similar ratio was also found in inner midribs, but their total sugar content was lower than inner leaf laminae. Relatively low levels of sucrose were found in all parts of Chinese cabbage. Total sugars decreased, but the relative composition of individual sugars did not change during storage. Exposure of Chinese cabbage to 30 or 40% CO2 for 5 or 10 days was detrimental to quality. Short-term exposure to high but noninjurious concentrations of CO2 (10–20%) showed no beneficial effect on quality retention during subsequent storage in air at 0°. However, low O2 (1%) atmosphere was very effective in extending the storage life of Chinese cabbage at 0°. It slowed down the decline of ascorbic acid and sugar contents, delayed the loss of chlorophyll and yellowing of the leaves, and reduced the incidence of decay. The Chinese cabbage was not salable without extensive trimming after 3 months of storage at 0° in air, whereas those in 1% O2 at 0° were still in salable condition after 5 months of storage with only slight trimming. No off-odor, off-flavor, or other symptoms of suboxidation were found at the end of 5 months of storage in 1% O2 at 0°.