Study On The Changes Of Nutrient Quality And Fresh-keeping Methods Of Postharvest Cerasus Humilis

In this experiment,the 'Mongolian' series of Cerasus humilis fruit were used as the test material.The changes of storage effect,nutritional quality of Cerasus humilis after harvest under normal temperature and low temperature and the effects of different fresh-keeping measures on the preservation effect of Cerasus humilis were studied.The purpose of the experiment was to explore the changes of nutritional quality,suitable storage temperature and preservation measures after harvest,and to provide the basis for storage after harvest of Cerasus humilis.The main results of this study were as follows:1.Cerasus humilis fruit can be stored for 10 d under normal temperature,for 30 d under low temperature;the storage time of Cerasus humilis fruit was significantly prolonged under low temperature.2.Under normal temperature,the content of soluble solids and soluble sugar increased first and then decreased,sucrose showed a decreased-increased-decreased trend,glucose and fructose contents showed a increased-decreased-increased trend overall,sorbitol increased overall;at the end of storage the contents of various sugars were higher than those before storage.Under low temperature,the content of soluble solids,soluble sugar,sucrose and fructose increased first and then decreased,the content of glucose and fructose increased first and then decreased,sorbitol increased overall;at the end of storage the contents of soluble solids and sucrose were slightly lower than those before storage,and the contents of other sugars were higher than those before storage.Under normal temperature,the contents of acid,malic acid and shikimic acid increased first and then decreased,the contents of citric acid and quinic acid decreased first and then increased,the contents of tartaric acid showed a increased-decreased-increased trend,and the contents of succinic acid increased;at the end of storage the content of malic acid was lower than that before storage,and the content of other acids were higher at the end of storage than those before storage.Under low temperature,the contents of acid,malic acid,tartaric acid,succinic acid and shikimic acid increased first and then decreased overall,while the contents of quinic acid increased overall and the contents of citric acid showed a decreased-increased-decreased-increased trend;the contents of titratable acid,malic acid,citric acid and shikimic acid were slightly lower at the end of storage than those before storage,and the contents of other acids were higher than those before storage.The variation range of sugar and acid content under low temperature were slower than those under normal temperature.3.Under normal temperature,the total calcium,effective calcium,alcohol calcium and water calcium content increased,the calcium content of pectin decreased,calcium phosphate,calcium oxalate and residual calcium increased first and then decreased;the contents of calcium oxalate and residual calcium were lower at the end of storage than those before storage,and the contents of other calcium were higher at the end of storage than those before storage.Under low temperature,the total calcium and calcium content of pectin decreased,the effective calcium,alcohol calcium and water calcium increased,calcium phosphate,calcium oxalate and residual calcium increased first and then decreased;the effective calcium,water soluble calcium and alcohol soluble calcium content were higher at the end of storage than those before storage,and the other calcium content were lower at the end of storage than those before storage.The variation range of calcium content under low temperature slower than that those under normal temperature.4.Under normal temperature,the contents of total phenol and proanthocyanidins increased,the contents of total flavonoids,total anthocyanins and flavonols increased first and then decreased,the contents of phenolic substances were higher at the end of storage than those before storage;under low temperature,the content of phenolic substances increased first and then decreased,the total phenol content was slightly lower at the end of storage than that before storage,and the content of other phenolic substances were higher at the end of storage than those before storage.The variation range of the content of various phenolic substances under low temperature were slower than those under normal temperature.5.Under normal temperature,the post-harvest storage period was short,the water loss was serious,the content of each nutrient substance changed more violently,can not maintain higher quality for a long time;under low temperature,the fruit preservation time was long,the nutrient content changed slowly,can maintain higher quality for a long time.6.Under low temperature conditions,the hardness of the control fruits decreased obviously after 30 d of storage,and the weight loss rate increased rapidly after 40 d and began to rot.Compared with the control,different concentrations of calcium chloride,sodium nitroprusside,salicylic acid,chitosan treatment and heat treatment at different temperatures all had certain preservation effect.Of these,0.5 mmol/L and 1.0 mmol/L salicylic acid treatment,1.0%and 1.5%chitosan treatment,40? or 45 heat treatment,the fruit hardness obviously decreased and the fruit began to rot 5?10 later than the control,the weight loss rate of the fruit was lower than that of the control,and it had a good effect of keeping fresh.