Effect Of Different Coating Treatment On Shelf Life Quality Of Candy Apple Before Storage

The unique advantages of Aksu,such as sufficient sunlight,large temperature difference between day and night,and irrigation with alpine snow water,give the’Red Fuji’apple a unique taste.The flesh around the vascular bundle of the’Red Fuji’apple is semi transparent in the later stage of maturity,resembling a’sugar heart’.Apples are respiratory climacteric fruits.Aksu ice candy heart apples are stored in cold storage and placed at room temperature for sale.Due to temperature changes,browning of the sugar heart may occur.It is very important to maintain the quality of the apples and maintain their commercial value after a certain period of refrigeration.In this experiment,in order to maintain the freshness and excellent quality of Aksu"rock sugar heart"apples during the shelf life after refrigeration,and to delay or reduce the phenomenon of apple browning or decay during the shelf life after refrigeration,Fuji apples from Aksu production area in Xinjiang were used as test materials.Fuji apples were coated with calcium chloride,ascorbic acid,oxalic acid,and citric acid to determine the changes in fruit quality during the normal temperature shelf life after being processed and refrigerated,To explore storage plans to extend the shelf life of refrigerated sugar heart apples,and to provide theoretical basis for providing high-quality Aksu"ice sugar heart apples"to consumers in production.The results were as follows:（1）After cold storage,the water loss rate,solid acid ratio,browning index,total phenol content,and the activity of poly galactose uronase（PG）of the fruits showed an upward trend;Hardness,sugar heart rate,sugar Cardiac index,titratable acid content,soluble sugar content,vitamin C（VC）content,sensory appearance,sensory smell,sensory taste,and sensory texture showed a downward trend;The changes in soluble solids were not significant;The flavonoid content,phenylalanine ammonia lyase（PAL）activity,and polyphenol oxidase（PPO）activity showed a trend of first increasing and then decreasing.（2）Through the determination of various quality indicators of apple fruit,7%Ca Cl₂,2%citric acid,6%ascorbic acid and 1%oxalic acid were screened as the optimal concentrations of each coating film.（3）Through principal component analysis of the effects of the best concentration of each treatment on the intrinsic quality,sensory quality,and browning of fruits during shelf life,it is preliminarily speculated that7%Ca Cl₂ and 2%citric acid coating treatment can improve the intrinsic quality of fruits during shelf life;Coating with 7%Ca Cl₂ and 2%citric acid can improve the sensory quality of fruits during shelf life,with 2%citric acid having the best effect;The coating treatments of 7%Ca Cl₂,2%citric acid,6%ascorbic acid,and1%oxalic acid have significant inhibitory effects on the browning of apple fruits during shelf life.Different coating treatments have varying degrees of impact on the quality,browning,and sensory evaluation of apple fruits during shelf life.The highest score is achieved under the 7%Ca Cl₂treatment.The 7%Ca Cl₂ treatment has the best effect on improving the quality of apple fruits during shelf life,enhancing sensory performance,and inhibiting browning;2%citric acid treatment has the best effect on improving the sensory properties of fruits during shelf life.Therefore,in actual production,7%Ca Cl₂ is recommended as the best coating treatment for apple storage,followed by 2%citric acid coating treatment.（4）The best comprehensive reagent 7%Ca Cl₂ was selected for validation after repeated treatment in the second year.The results showed that the 7%Ca Cl₂ coating treatment significantly reduced the water loss rate,solid acid ratio,total phenol content,PPO,PAL,and PG enzyme activity of fruits during shelf life after refrigeration compared to the control;The sugar heart rate and sugar Cardiac index of fruit were significantly increased;The contents of titratable acid,soluble sugar,VC and flavone in fruits during shelf life were significantly increased;Significantly improved the appearance,odor,taste,and texture of fruit sensory quality during shelf life;Further validated the effect of 7%Ca Cl₂ as the optimal coating agent.