Studies On Storage Technology Of Cassava And Sweet Potato

Tuber vegetable has edible hypertrophy underground stems or roots.It is economic valuable for being used as food and feed,and it is the industrial raw material of starch,sugar and alcohol.But tuber vegetable is sensitive to low temperature,perishable and easy to germinate,which seriously affecting the economic value while storage.In this study,the South China No.5 cassava(Manihot esculenta Crantz)and high line No.14 Sweet Potato(Ipomoea batata Lam)were chosen as test materials,the experiments were conducted under different storage temperatures,pre-cooling,ethanol fumigation and ultraviolet irradiation to study the postharvest physiology,storage quality and preservation effect.It provides the theoretical basis for prolonging the period of storage and transportation,improving the storage quality of cassava and sweet potato.The results are as follows:1.The experiment was conducted under different storage temperatures,including 5℃,10℃,15℃,20℃ and room temperature CK(32℃)to study the effects on postharvest physiology and quality of sweet potato.The results showed that:good fruit rates of CK,treatments 5℃,10℃,15℃ and 20℃ on the 42ed day of sweet potato storage were 40%,35%,40%,70%and 50%,respectively,and the good fruit rate of treatment 15℃ was significantly higher than the others(P<0.05),indicates that fruit quality of sweet potato stored at 15℃ was better compared with the room temperature.The decay rate and germination rate were lower,fruit firmness changed slowly,and the activities of SOD,POD maintained at a high level while content of MDA was minimum.Although starch content,TSS content of sweet potato stored between 5-10℃ changed slowly,but chilling injury occurred after 14 days of storage(symptoms:flesh browning,flesh firmness decreased significantly).It indicates that 15℃ is the storage temperature that helps maintaining the quality of sweet potato,and delays the ripening and senescence of fruit.2.The experiment was conducted under different ways of pre-cooling,including ice water,thermostat under 4℃,water shower and air pre-cooling with fans to study the fruit quality of sweet potato.Results indicated that:L values of CK,ice water pre-cooling,water shower pre-cooling,thermostat under 4℃ pre-cooling and air pre-cooling with fans on the 50th day of sweet potato storage were 73.04,76.92,75.42,77.48 and 77.74,respectively,all the L values of pre-cooling treatments were significantly higher than CK,indicates that compared with the control group,all pre-cooling treatments could effectively delay the fruit rotting,sprouting and softing,inhibit the conversion of starch to soluble sugar,keep the commodity value of sweet potato.Storage in thermostat under 4 ℃ for 12 hours did the best.3.Different concentrations of ethanol,including 250,500,1000,1500μl/L(there was no 1500μl/L conducted on cassava)fumigated on cassava and sweet potato,and the storage physiology and fruit quality were studied.The results showed that:ethanol fumigation could repress the ripping and aging process of cassava and sweet potato compared with the control group,it could effectively inhibit the change of sensory quality and nutritional quality.MDA contents of CK,250,500 and 1000μl/L on the 10th day of cassava storage were 4.26,3.81,3.25 and 3.06μmol/g,respectively,MDA contents of 500μl/L and 1000μl/L were significantly lower than the others(P<0.05).Ethanol concentration of 1000 μl/L did the best in maintaining the fruit quality of cassava,followed by 500 μl/L,and 250 μl/L did the worst;while 500μl/L was the most suitable ethanol concentration for sweet potato.4.The effects of different exposure time in ultraviolet irradiation,including 10,20,30,40min on cassava and sweet potato were studied.Results showed that:Sweet Potato storage through 35 days,10,20,30min and 40 min starch content of fruit processing were higher than the control group,0.88%,4.79%,4.47%and 1.61%,and the starch content of the fruit ultraviolet 20min and 30 min handling large,very significant higher than other treatments(P<0.01).compared with the control,30 min significantly reduced during storage Sweet drop in hardness,postpone changing color of the fruit to maintain starch content,SOD and POD activity at very high levels,inhibit the growth of MDA content and TSS,followed by 20 min,10 min results.And cassava also 30 min irradiation time best.