Detection of Phenylalanine Ammonia‐Lyase in the Skin of Blueberry and Cranberry Fruits

Phenylalanine ammonia‐lyase (PAL) was extracted from the skin of individual berries and assayed spectrophotometrically under conditions minimizing interference from co‐extracted constituents. Analyses for total anthocyanin (TAcy), soluble solids (SS), and titratable acidity (A) were performed on the same berries. In blueberry fruits, PAL activity was present at all maturity levels examined. Cultivar differences in anthocyanin accumulation were unrelated to PAL activity. PAL activity in cranberry fruit was unrelated to harvest date, cultivar differences in anthocyanin accumulation, or values of TAcy and SS/A in individual berries. Activity was retained in cranberries during 4 wk of refrigerated storage.