Abstract:

The color of apple has a direct impact on its quality and storability. We used apples with a percentage of red color
area no less than 80% or no more than 20% to analyze their quality parameters, polyphenols and related enzyme activities
during low-temperature storage. The quantitative analysis of polyphenols was performed by HPLC. The physicochemical
analyses showed that a constant decrease in fruit firmness was observed, whereas soluble solids content and pH increased
continuously during storage. The changes in total polyphenol and mono-phenol contents consistently followed a decreaseincrease-
decrease trend and reached peaks after 100 days of storage. Concurrently, the activity of phenylalnine ammonialyase
(PAL) attained a peak. However, the activities of polyphenol oxidase (PPO) and peroxidase (POD) reached their peaks after
50 and 150 days of storage, respectively. All of the three enzyme activities were closely related with polyphenols content in apple.
All of the above results demonstrate that apple has the maximum nutritional value when the storage period is 100 days.

Key words: apple, low-temperature storage, physicochemical indicators, enzyme activity, polyphenols