Study On Storage Of Postharvest Chinese Cabbage With Humidcool And Ozone

Brassica chinensis var.Tsai-tai has high nutritional value because it is rich in nutrition,such as cellulose,vitamins,calcium,zinc,essential amino acids and some flavonoids.Consumers of Guangdong province almost eat it each meal.At present,the shelf life is very short(3~4 days)and it is difficult to meet the demand of the market and long distance exporting sales and transportation need.The experimental study and report on its postharvest storage are also little,so the current situation that due to the short shelf life that caused Brassica chinensis var.Tsai-tai been spoilaged and suffered large numbers of losses should be solved quickly.Therefore,it has an important practical significance to study postharvest storage characteristics of Brassica chinensis var.Tsai-tai.In order to provide basis for the longe time and safety storage for postharvest Brassica chinensis var.Tsai-tai,the study took the lv he 80days late Brassica chinensis var.Tsai-tai as materials and discussed storage quality and physiological changes of postharvest Brassica chinensis var.Tsai-tai by different pre-cooling mode,ozone gas concentrations and storage methods.The results are as follows:1.Pre-cooling treatment could reduce etiolation and decay rate of Brassica chinensis var.Tsai-tai and kept the hardness unchanged.Among them,the sensory quality by pre-cooling without humidification treatment was best.After six days of room temperature storage,the Brassica chinensis var.Tsai-tai had a sensory score of14,weight loss rate of 20.13%,yellowing rate of 31.40%,decay rate of 39.40%and the hardness value of 2.89kg.2.In the same humidicool conditions(temperature for 2 to 3 degrees,relative humidity for 90~95%),different ozone gas concentrations(2.14mg/m~3,4.28mg/m~3,6.42mg/m~3,8.56mg/m~3,10.72mg/m~3)treatment could inhibit flava and decay rate of Brassica chinensis var.Tsai-tai.But high concentrations(more than 6.42mg/m~3)would accelerate water losing rate and produce toxic effects on blades,It had the best sensory quality by 4.28mg/m~3 ozone treatment and a sensory score of 30,weight loss rate of 0.41%,yellowing rate of 0.78%and decay rate of 1.41%after 10 days of storage.3.In the same humidicool conditions,low ozone gas concentrations could reduce the V_C oxidation and decomposition rate,but the high concentrations(more than6.42mg/m~3)would accelerate the degradation of V_C.A certain ozone gas concentration could inhibit the protein decreased,but it had little effect on soluble solids and soluble sugar.The 4.28mg/m~3 ozone treatment kept the nutritional components`s loss least.It had a soluble solids of 2.44%,soluble sugar of 4.19mg/g,soluble protein of 94.58mg/100g and V_C of 52.16?g/g after 10 days storage4.In the same humidicool conditions,ozone gas that less than 6.42mg/m~3 could inhibit the reduce of chlorophyll a,chlorophyll b,total chlorophyll and kept the leaves original luminance,red and green value,saturation and chroma angle,thus reducing color change and keeping products good color.High ozone concentrations(more than8.56mg/m~3)could accelerate the degradation of chlorophyll and change of color.In this experiment,4.28mg/m~3 ozone gas kept the leaves color best.5.In the same humidicool conditions,ozone gas had a good sterilization ability on the surface bacteria,mould and yeast of Brassica chinensis var.Tsai-tai,and its sterilization ability gradually increased with the increasing of ozone gas concentrations.2.14~10.72mg/m~3 ozone treatment could reduce the total number of bacteria by 2 to 3 orders of magnitude,yeast and mold counts by 1 to 2 orders of magnitude.6.Ozone and humidicool storage could inhibit Brassica chinensis var.Tsai-tai leaf yellowing,weight losing,rotting and petiole hardness decreasing.At the end of ozone and humidicool storage,the Brassica chinensis var.Tsai-tai had a weight loss rate of6.37%,etiolation rate of 5.51%,decay rate of 3.07%and hardness value of 4.38kg.It had a huge significant difference with room temperature storage.7.Low temperature(2~3?)could delay the peak time of soluble solids and reduce the degradation rate of soluble sugar,protein and V_C.It had a significant difference with room temperature storage.Brassica chinensis var.Tsai-tai remains the nutrient content highest,wich had the soluble solid of 2.53%,soluble sugar of 4.57mg/g,soluble protein of 85.94mg/100g and V_C of 63.35?g/g,at the end of ozone and humidicool storage,8.At the end of the ozone and humidicool storage,the surface bacteria,yeast and mold of Brassica chinensis var.Tsai-tai respectively was 4.70×10~4,5.43×10~2,2.11×10~3.It decreased by 97.59%,98.47%and 96.11%compared with the beginning.It had great difference with other storage methods.9.Ozone and humidicool storage had reduced respiration intensity of Brassica chinensis var.Tsai-tai.At the end of the storage,the respiratory intensity of Brassica chinensis var.Tsai-tai decreased by 36.81%compared with room temperature storage.10.Ozone and room temperature storage could improve the SOD and CAT activity of Brassica chinensis var.Tsai-tai,but it had no significant effect on POD enzyme activity.At the end of the storage,the POD,CAT and SOD activity respectively was2853.93 U/gFW·min,322.88U/gFW·min,287.24 U/gFW·h,which was significantly higher than that of other storages.