Polyphenoloxidase (PPO) activity and polyphenol concentrations decreased during maturation and remained relatively constant during cold storage. However, there was no set pattern of changes in degree of browning during maturation and cold storage. Not all cultivars showed the same relationship between degree of browning and enzyme activity. In some cultivars (Classic Delicious, RI Greening, McIntosh and Cortland), PPO activity was directly related to degree of browning while in others (Empire, Rome and Golden Delicious), degree of browning was related more to phenolic concentration. High performance liquid chromatography analysis of the phenolics in apples showed that the types of phenolic compounds in all cultivars were similar and that no one particular compound could account for the differences observed in browning.

Twelve cultivars were prepared as slices and stored 12 days at 2°C. Changes in respiration and quality factors were compared. Initial respiration rates among cultivars varied from 3.5 mL CO&g/hr in Delicious to 7.6 mL CO&$hr in Monroe and decreased rapidly during the first 3 days. Idared, McIntosh, Delicious, and Rome showed relatively low respiration throughout storage. Firmness of slices during storage decreased gradually for 7 days and more rapidly thereafter. Empire, Golden Delicious, and Idared apples showed minimum changes in &miess. Change in color of slices was rapid during the first 3 davs. Cortland. Emuire. Golden Delicious. New York 674. and Deliious showed-least'brc&ing. Titratable acidity, pH, soluble solids, and weight changes during storage were small and varied by cultivar. NY674, Cortland, Golden Delicious, Empire, and Delicious showed more desirable attributes for minimal processing.

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