1 week, 4 days ago

Nothing is absolute, so is this sentence. 

No matter what kind of fruit, it has its best storage temperature, for example, the best storage temperature of mango is 10 ℃ ~ 13 ℃. When storing fruit, if the temperature is higher than the optimal storage temperature, the fruit is easy to deteriorate and rot, and lower than the optimal storage temperature, the fruit is vulnerable to chilling injury. Chilling injury refers to the damage of fruits caused by low temperature storage above freezing point. Common chilling damage phenomena include banana and mango which are easy to turn black when stored at low temperature, apples and pears are prone to water stains when stored at low temperature, kiwifruit will suffer from skin browning, lignification and so on. 


 
 kiwifruit chilling injury performance. The image is from Jiangtao Suo et al. Characteristics of killing induced alignment in kiwi fruit with different sensitivities to low temperatures [J]. Postharvest biology and technology, 2018, Therefore, 
 whether it is tropical fruit or not, as long as the storage temperature is not within the optimal storage temperature range, it is not suitable. 


The subject mentioned that the mango stored in the southern weather above 35 ℃ for 2 days has been far beyond the optimal storage temperature, and it is not surprising that the deterioration occurs. After that, the author put the mango in the refrigerator (0 ~ 4 ℃) for a week. Although it was not in the optimal storage temperature range, the result was "almost perfect". Is mango immune to chilling injury? 

Of course not. From the experiments conducted by the subject, we can see that: 1. Compared with the spoilage caused by high temperature storage, chilling injury is at most a "slight injury" to fruits; 2. The damage caused by chilling injury to fruits takes a certain time, and the effect of chilling injury on fruits is not obvious in a few days or even a week or two. 


 people who put forward the idea that "tropical fruits can't be put in the refrigerator" should have considered the results of low temperature damage, but they have ignored the phenomenon that high temperature storage will accelerate the deterioration of tropical fruits. From this point of view, the saying "tropical fruits can't be put in the refrigerator" is actually questionable. 


Generally speaking, the best storage temperature of tropical fruits is about 5 ~ 15 ℃, which is higher than the refrigeration temperature of refrigerator. If the room temperature at home is more than 30 degrees, then let "tropical fruits can not be put in the refrigerator" to hell, and quickly put the fruits in the refrigerator; but if the room temperature at home is more than 10 degrees, it is better to put the fruits in a cool indoor place than in the refrigerator. In addition, 
 immature fruits are more sensitive to low temperature and are more vulnerable to chilling injury, while fruits with high maturity have stronger cold resistance. 
 therefore, the refrigerator is only suitable for storing mature fruits, and it is better to put the fruits without maturity outside the refrigerator. 


 
 peach chilling injury. The picture is from Susan Lurie et al. Chilling injury in peach and nectarine [J]. Postharvest biology and technology, 2005, 37:195-208. 
 
 
 to solve the problem, let's see how to store fruits more scientifically. Before analyzing, let's understand two concepts. 


 from the perspective of mature physiological characteristics, fruits can be divided into respiratory climacteric type and non respiratory climacteric type 
. The so-called 
 respiratory climacteric fruit 
 refers to the fruit with rapid increase of respiration rate and a large amount of ethylene production at the same time. Their fruits have obvious stages in development and maturity, which often give people the feeling of "suddenly ripe". The common respiratory climacteric fruits are 
 banana, kiwi fruit, mango, persimmon, tomato, apple, pear, peach 
 and so on. 


 non climacteric fruits 
 refer to the fruits without obvious respiratory rate peak and ethylene peak during fruit ripening, and their fruits have no obvious stages in development and maturity, basically synchronous, that is, the process of ripening is relatively gentle without sudden changes. The common non climacteric fruits are 
 grape, orange, strawberry, cherry 
 and so on. 


 
 the picture is from Baidu entry 
 
 
 to distinguish whether a fruit is respiratory climacteric or non respiratory climacteric, the relatively simple method is to see whether it can be ripened after picking. For example, the respiratory climacteric fruit banana, even if picked is green and hard, not fully mature fruit, but put in the house for a few days or with ethylene to urge, can also become sweet and delicious ripe fruit. But grapes, oranges and other non climacteric fruits are not the same. If their fruits are picked when they are not ripe, that is, no matter how high the concentration of ethylene is used, they can not be accelerated to ripen. The sour ones are still sour, the ones that should be tasteless are still tasteless, and they will not ripen and become sweet after a long time, but will only deteriorate and rotten. 


 this means that respiratory climacteric fruits can be picked before the fruits are fully mature, while non climacteric fruits can only be picked after they mature on the fruit branches. 
 this tells us that climacteric fruits will have a longer "life" because we can put immature fruits in the house and let them mature slowly, while non climacteric fruits are mature when they are bought back and will soon be damaged if they are not eaten in time, so the shelf life is relatively short. 

So, before we use fruit storage, we need to think about the types of fruit a little bit. 

If it is respiratory climacteric fruit, generally speaking, it is more sensitive to cold (especially in tropical areas). No matter whether it is mature or not, as long as the temperature at home is not too high, it is not necessary to put it in the refrigerator; if the temperature at home is too high (room temperature in summer), the ripe fruit can be put into the refrigerator, and the immature fruit should not be put in the refrigerator, because For the immature fruit is more vulnerable to chilling injury, not only will lead to quality decline, and even can make it lose the ability to ripen, it is recommended to put it into the refrigerator after ripening. 

If it is a non climacteric fruit, generally speaking, it is more tolerant to cold, and it is mature when it is bought back. It is recommended to put it in the refrigerator in time to reduce the respiration of the fruit and prolong its shelf life.

Comment

No Comment Yet.