Fig. 3

Temperature cycling affects aronia berry polyphenols. Aronia berry was subjected to repeated frozen temperature cycling and analyzed for (A) extractable total phenols by Folin–Ciocalteu method as gallic acid equivalents (GAE); (B) extractable monomeric anthocyanins by pH differential method as cyandin-3-glucoside equivalents (C3GE); (C) extractable proanthocyanins by 4-dimethylaminocinnamaldehyde (DMAC) method as catechin equivalents (CE); (D) extractable polyphenol oxidase (PPO) activity; (E) juice °Brix, (F) juice titratable acidity; (G) juice pH; and (E) juice °Brix: acid ratio. Week 0 represents analysis of unfrozen fresh berries picked within 6 h. A unit of PPO activity is a 0.001 change in absorbance per min (△A420/ min). Data are means ± standard deviation of n = 4 aliquots aronia plants, with triplicates for each plant. Data were analyzed by one-way ANOVA with Tukey’s multiple comparison test vs. the fresh sample, * P < 0.05 vs. cycle 0