Study On Key Technologies For Preservation In Cold Chain Logistics Of Zizania Latifolia

Zizania latifolia, a aquatic vegetable grown uniquely in China,is one of popular vegetables which has full of amino acids, minerals, tender texture, delicious flavor and medicinal value. Zizania latifolia has a short shelf life of 3-5 days at room temperature, after that browning and lignification will show, commercial and edible value will reduced rapidly. This experiment selects Zizania latifolia as objects, studys the key links in cold chain logistics such as pre-cooling, transportation, packing and sales, and explores comprehensive evaluation of Zizania latifolia in order to provide a theoretical basis for cold chain logistics of Zizania latifolia. The main conclusions are as follows:(1)The effect of three pre-cooling methods on Zizania latifolia was studied. The results showed that, the central temperatures of Zizania latifolia with ice water pre-cooling,cold room pre-cooling and ice water+cold room pre-cooling were decreased from room temperature to 4℃,the pre-cooling time was 330 min,540min and 300 min respectively. Weight loss was negligible when Zizania latifolia were pre-cooling with the method of ice water pre-cooling and ice water+cold room pre-cooling, while weight loss of Zizania latifolia with cold room pre-cooling was up to 5.125%.(2) The effect of different packing on the quality of Zizania latifolia during the cold chain transportation was studied. The results showed that, the reduction in weight loss was higher in Zizania latifolia that were packaged in PE bags with 0.03 mm than the weight loss from Zizania latifolia samples that were packaged in 0.01 mm and 0.02 mm PE bags. POD activity only increased by 35.89% in 7 days when Zizania latifolia were wrapped in 0.03 mm PE bags which had benefit to inhibit respiration, delay enzymatic browning and reduce the increase of lignin. Weight loss, POD activity, PPO activity were significantly inhibited when Zizania latifolia were packaged in vacuum packaging and modified atmosphere packaging, which slowed down the rate of metabolism and had the effect of anti-aging. Comprehensive evaluation scores of seven kinds of packaging were got by the methods of principal component analysis and factor analysis. The scores showed that the best quality of Zizania latifolia were stored in vacuum packaging after 7 days, followed by modified atmosphere packaging and 0.03 mm PE bags packaging.(3) The effect of three transportation methods on the quality of Zizania latifolia was studied. The results showed that, no significant differences of sensory evaluation were observed among three transportation methods in 48 hours, so transportation method was selected arbitrarily. On the third day, sensory evaluation scores of Zizania latifolia transported in polystyrene case with ice placed in normal temperature and carton with PE bag placed in normal temperature were 3.8 and 2.96 respectively. Respiration rate was restrained and browning was inhibited when Zizania latifolia were transported in polystyrene case with ice placed in normal temperature, so this method could be used in the situation of transporting in 48-72 hours. When Zizania latifolia were transported in carton with PE bag placed in 1℃ refrigerating cabinet, PPO activity and POD activity were restrained, the synthesis of cellulose and lignin were inhibited, weight loss was only 0.583% after 7days. In conclusion, this method was better than other two methods on long-term transportation. So it was appropriate to select cold temperature transportation if transportation time was longer than 72 hours.(4) The effect of four sales methods on the quality of Zizania latifolia was studied. The results showed that, Zizania latifolia, placed in PE shrinkable film, had low weight loss and little browning because water evaporation was decreased. Otherwise, fibrosis and lignification were inhibited and the content of Vc was reserved extremely. When Zizania latifolia were selled at 4℃,freshness could be better maintained and sensory evaluation score was higher. The loss of soluble solids was reduced,water evaporation and Vc were further reduced.Thus, Zizania latifolia with PE shrinkable film at 4℃ were best and increased commercial and edible value.