Changes Of Thermal Properties And Quality Properties Of Cold Sensitive Under Low Temperature Stress

Temperature is one of most important factors affect the physiological changes in postharvest fruit storage, the low temperature storage is also thought to be the most effective way to storage of fresh fruit fresh keeping, but sensitive type fruit above the freezing point of low temperature storage is associated with metabolic disorders and physical injury within the fruit. Cucumber is a kind of typical sensitive fruits and vegetables, is one of the world’s ten biggest vegetables. Eggplant, zucchini, cucumbers, sensitive fruits stored at low temperature conditions of the physiological metabolic disorder and the membrane structure damage, i.e. the chilling injury. Predecessors to sensitive fruits fruit during storage under low temperature adversity, the membrane permeability and protein enzyme activity of the fruit, etc. A lot of research on physiological and biochemical characteristics, but for Sensitive fruit under low temperature adversity less study the change rule of its thermal properties. This study selected the eggplant, zucchini, cucumbers, sensitive fruit as the research object, such as to determine its freezing point, soluble solids, thermal conductivity, specific heat and other characteristic parameters as the basis, to find low temperature stress affect Sensitive thermal characteristic parameters of fruit, proven Sensitive fruit chilling injury occurred in the process of dynamic change law of characteristic parameters of heat transfer for the next Sensitive thermal characteristic parameters in the process of chilling injury and fruit tissue cell membrane permeability and cell morphology and Sensitive fruit low-temperature chilling injury index of the relationship between research provides theoretical and experimental basis. The main results were as follows: the fruit postharvest storage temperature is affect the physiological changes in one of the important factors, the low temperature storage is also thought to be the most effective way to storage of fresh fruit fresh keeping, but sensitive type fruit above the freezing temperature of cryogenic storage easy to cause the fruit internal metabolic disorders and physical injury. Cucumber is a kind of typical sensitive and vegetables, is one of the world’s ten biggest vegetables. Eggplant, zucchini, cucumbers, sensitive stored at low temperature conditions of the physiological metabolic disorder and the membrane structure damage, i.e. the chilling injury. Predecessors to sensitive fruits fruit during storage under low temperature adversity, the membrane permeability and protein enzyme activity of the fruit, etc. A lot of research on physiological and biochemical characteristics, but for Sensitive fruit under low temperature adversity less study the change rule of its thermal properties. This study selected the eggplant, zucchini, cucumbers, Sensitive fruit as the research object, such as to determine its freezing point, soluble solids, thermal conductivity, specific heat and other characteristic parameters as the basis, to find low temperature stress affect Sensitive thermal characteristic parameters of fruit, proven Sensitive fruit chilling injury occurred in the process of dynamic change law of characteristic parameters of heat transfer for the next Sensitive thermal characteristic parameters in the process of chilling injury and fruit tissue cell membrane permeability and cell morphology and sensitive fruits low-temperature chilling injury index of the relationship between research provides theoretical and experimental basis. The main results were as follows:1、Low temperature conditions, the thermal characteristics of different kinds Sensitive fruit parameters and quality parameters change research, the eggplant, zucchini, and cucumber fruits of thermal conductivity, specific heat, freezing point, soluble solids content, water content and other parameters are determined. Under the low temperature storage, the moisture content of three kinds of sensitive fruit will be as the storage time prolonged due to the reason of the evaporative water loss decreases; Intimidation of fruit internal physiology, fruit will rapidly aging, the pulp of fruit soluble solids content will have corresponding change tendency; The freezing point of three kinds of fruit because affected by the change in the total soluble solids and rising trend. Three kinds of fruits and vegetables obvious differences in thermal conductivity, thermal conductivity of eggplant, and thermal conductivity of cucumber biggest; Fresh eggplant, zucchini, cucumbers, thermal conductivity were 0.219, 0.447, 0.533 W/(m K), 2 days in storage of eggplant thermal conductivity in the peak of 0.254 W/(m K), on the fourth day of squash and cucumber storage thermal conductivity in the peak were 0.451, 0.540 W/(m K);Then a downward trend, until 10 days, were reduced to 0.215, 0.421, 0.215 W/(m K).2 、 Different varieties of the same maturity sensitive thermal characteristic parameters of fruit under low temperature adversity and quality characteristic parameters change research, the result of the flowering after five days, ten days, 15 days of green cucumber fruits of thermal conductivity, specific heat, freezing point, soluble solids content, water content and other parameters are determined. Cucumber and cucumber in 2 ℃ storage appeared a chilling injury, the first 2 days of cucumber chilling injury in storage after 4 days. To the end of the experiment, the small, medium and large cucumber, the weightlessness rate of those two groups were 3.27%, 3. 60, 4.86%.In low temperature conditions, three kinds of cucumber as the extension of storage time its soluble solids will reduce gradually, for fruit and vegetable freezing point and its soluble solids are positive correlation, so may result in the experiment of the freezing point of cucumber fruits as the storage time increased. Small, medium and large heat capacity of the fresh cucumber is 3.96, 3.93 and 3.93 k J/(kg * K).The heat capacity of the different maturity cucumber is a trend of declining, down the proportion of 3.47%, 3.60% and 4.86%, respectively. New small, medium and large cucumber thermal conductivity is 0.526, 0.533, 0.544 W/(m K), to 10 days of its thermal conductivity and finally were 0.518, 0.528, 0.522 W/(m K).First chilling injury in cucumber in the turning point of the thermal conductivity and its time is relatively consistent, before, during and after the reason may be that the cucumber fruit under chilling injury tissue cells of the phase transformation in the biofilm, membrane lipid from liquid state to gel state, membrane lipid phase change also led to the plasma flow stops, thus lead to the organizational structure of the cucumber has changed, changed caused the heat transfer ability.3、Under different low temperature adversity Sensitive the thermal characteristic parameters and the quality of the fruit characteristics parameters of experimental research, the red and green cucumber fruits of thermal conductivity, specific heat, freezing point, soluble solids content, water content and other parameters are determined. Cucumber in 2, 5, 8 ℃ low temperature storage were chilling under adversity, the initial onset of chilling injury of 1 day, 4 and 8 days respectively, and under the critical temperature of 11 ℃, there was no chilling injury of cucumber. Under different low temperature adversity, cucumber as the extension of storage time its soluble solids will reduce gradually, the experiment of cucumber fruits of freezing point as the storage time increased. Under the same relative humidity, the weightlessness rate of cucumber fruit under different low temperature adversity with the increase of storage temperature and storage time increased with the extension of reason, 10 days after 2, 5, 8, 11 ℃ between groups of weightlessness rate were 3.17%, 3.6%, 4.26% and 3.6% respectively. The heat capacity of the fresh cucumber is 3.93 k J/kg * K), due to the influence of cucumber continuous water loss during storage, the heat capacity of the cucumber has a tendency to gradually reduce, to the end of the experiment 2, 5, 8, 11 ℃ between groups of specific heat were 3.81, 3.79 and 3.79 k J / * K(kg) and 3.73 k J/(kg * K), the lower the storage temperature fall of specific heat capacity is smaller. Cucumber fruit thermal conductivity under different low temperature adversity will change with the extension of storage time, fresh cucumber thermal conductivity is 0.53 W/(m K), to the end of the experiment, 2, 5, 8, 11 ℃ storage under the cucumber thermal conductivity were 0.45, 0.46, 0.45, 0.54 W/(m K).4 、 Low temperature conditions after temperature lift Sensitive fruit thermal characteristic parameters and quality parameters before and after the change research, the eggplant, zucchini, cucumbers, fruit under low temperature adversity after temperature before and after the lifting of thermal conductivity, specific heat, freezing point, parameters such as soluble solids content, moisture content were determined.3 fruitcake is thawing 2 d after its moisture content will fall further, and the magnitude of the decrease significantly faster than at low temperature, in 10 days, the moisture content of eggplant, zucchini, cucumbers, after thawing was 91.23, 90.24, 93.45%, weight loss rate of 3.03, 4.95, 4.44% respectively. After thawing the soluble solids content of the three kinds of fruits fall further; The freezing point, after wen appeared rising trend.10 days of the eggplant, zucchini, cucumbers, soluble solids were 4.51, 4.82, 5.07%, freezing point, respectively 0.62, 0.29, 0.76 ℃.The 10 th day after thawing eggplant, zucchini, cucumbers, specific heat capacity were 3.75, 3.78 and 3.78 k J/kg *(K), thermal conductivity were 0.321, 0.465, 0.552 W/(m K).