Effects Of Calcium Chloride Treatment On Preservation And Softening Of Red Raspberry Fruit During Low-temperature Storage

Red raspberries have a high metabolism rate after harvest,its tissue is delicate and easy to soften and rot,which is the main limit to its storage and transportation.Softening is the characteristic feature during ripening of red raspberry fruit,which is unavoidable even when stored at low temperature.Calcium chloride?CaCl₂?is a commonly used chemical preservative,which is easy to operate and can effectively maintain the quality of fruit storage,especially in the aspect of delaying softenin.Until now,the softening of red raspberry fruit after CaCl₂ treatment is not determined,and the effects of low temperature combined with CaCl₂ treatment on the quality and softening of red raspberry berries have not been clarified.In this paper,‘Australian Red'red raspberry was used as material to study the effects of different concentrations of CaCl₂ treatment on the quality and softening of red raspberry during low temperature?0??storage.The main results showed as follows:?1?Postharvest red raspberries were immersed in different concentrations of CaCl₂solutions?0,1%,2%,and 4%?for 3 minutes,and then stored at low temperature after natural air-drying.The results showed that 1%and 2%CaCl₂ treatment reduced the respiration rate of fruit during storage,slowed down the decrease in fruit firmness,titritable acidity?TA?content,soluble solids?TSS?content,ascorbic acid?AsA?content and total phenolic content,and the increase in malondialdehyde?MDA?content,inhibited the polyphenol oxidase?PPO?activity,and simultaneously promoted the peroxide peroxidase?POD?activity and catalase?CAT?activity,whereas the 4%CaCl₂ treatment had the opposite effect.Therefore,the suitable concentration of CaCl₂ treatment could effectively maintain the storage quality of the postharvest red raspberry fruit,and the effect of the 2%CaCl₂ treatment was the best.?2?The red raspberry fruit were immersed in 2%CaCl₂ for 3 minutes,and then stored at low temperature after natural air-drying.The results showed that compared with the control,2%CaCl₂ treatment can significantly delay the decrease of the protopectin content,cellulose content and starch content,inhibit the increase of soluble pectin content,and simultaneously inhibit the activities of polygalacturonic acid?PG?,pectin methylesterase?PME?,?-galactosidase??-gal?,cellulase?Cx?and amylase?AM?of the red raspberry fruit during low-temperature storage.Therefore,postharvest calcium chloride treatment could delay the softening of red raspberry fruit during low-temperature storage by delaying cell wall degradation and starch hydrolysis.In summary,the appropriate concentration of CaCl₂ treatment can delay the softening,effectively maintain the storage quality,and delay the ripening and senecence of red raspberry fruit,thus prolonging its storage life.