Australian studies on storage and packaging of Asian leafy vegetables, Chinese waterchestnut, and Kabocha pumpkin

摘要

Recent investment in postharvest research programs has provided substantial improvements in the quality and supply of Asian vegetables in Australia. Development of product descriptors, and optimum postharvest handling and packaging protocols, have improved quality and reduced wastage. Crops like pak choi (Brassica rapa var. chinensis) and gai lum (Brassica oleracea var. alboglabra) are now a permanent part of the vegetables on offer at mainstream supermarkets throughout Australia. Modified atmosphere (MA) packaging has been developed for many Asian leafy vegetables and herbs in conjunction with the investigation of appropriate cool storage temperatures to maintain quality and avoid chilling injuries. Quality following storage of 11 leafy Asian vegetables was demonstrated to be better from MA packaging than from 'high humidity' packaging that maintained an air atmosphere. Atmospheres high in CO_2 and low in O_2 generally helped to reduce leaf yellowing and the proliferation of rots. Research to optimise postharvest quality has also extended to biochemical analysis. Six varieties of 'Kabocha' pumpkins (Cucurbita maxima X C. moschata) grown for export to Japan were analysed for sugar content and carotenoid levels to help select product that best met market requirements. The colour of the flesh was also considered along with skin colour and skin blemishes. The Australian market demands quality Chinese waterchestnuts (Eleocharis dulcis) with a high level of sweetness in association with plump, crisp, and turgid corms. To minimise weight loss in stored corms and to promote sweetness, different packaging materials, storage temperatures, and storage durations were investigated. Over a 5-month storage period at either 1 or 9 deg C, weight loss of corms was acceptably low (i.e. less than 10 percent) if stored in either snap-lock bags made of low density polyethylene (LDPE) film, or 'Longlife' vegetable bags (microperforated LDPE film). Higher storage temperatures were associated with a decrease in sugar content and increase in sprouting.