Effect of Packaging on Storage Quality of Water Bamboo

Water bamboo (Zizania latifolia Turcz.) possesses fresh and tender tissue and its quality deteriorates rapidly after harvest due to high respiration. In addition to temperature, packaging method was considered as another important factor that will affect the deterioration rate. In this study, the effect of packaging on the quality of water bamboo during storage at 5℃ was investigated. The results showed that water bamboo packed in vacuum packages maintained its appearance as good as freshly harvested. On the other hand, water bamboo packed in sealed package and tied package showed shrunk appearance as the storage time increased, and there were hollowness and cracking within the tissue. For the unpacked treatment, its sheath leaf wilted after 3 days and its body shrank after 7 days with the appearance of bacteria contamination, and became totally unsalable. With respect to the effect of packing methods on quality changes during storage, the vacuum package showed least change in all the quality factors observed, including yellowing of sheath leaf, browning of cut end, hardness, water loss and total soluble sugar contents. It is followed by sealed and tied package, and the unpacked showed the worst changes.
Since the vacuum package showed the better result in maintaining the quality of water bamboo during cold storage, the conditions of vacuum package were further studies. When water bamboo was vacuum-sealed in LDPE bags of different thickness, most of the quality factors were not affected during cold storage. The only difference was the ethanol concentration inside the tissue, with 0,05 mm bags having lower ethanol than the 0.08 mm bags, indicating less anaerobic respiration. The degree of vacuum, which was controlled by the length of vacuum pumping, also affected the gas contents within the bag. The longer pumping time, the greater changes in oxygen reduction and carbon dioxide increase inside the bag. Twelve second pumping, which resulted minus 755 mmHg vacuum, was considered too long; because it results a rapid anaerobic condition and the accumulation of more anaerobic metabolites.
The results of this study indicated that the optimum vacuum package condition for water bamboo were: using 0.05 mm LDPE bags and vacuum packed with 6 second pumping to minus 680 mmHg vacuum, and stored at 5℃. The water bamboo will have a storage life of 4 weeks in good quality before the appearance of anaerobic off flavor.