Changes in fruit quality in black chokeberry (Aronia melanocarpa) during maturation

Summary

Black chokeberry fruits are rich in anthocyanins and can be used as a raw material for the production of natural food colourants. Fruit quality was studied during maturation in three true black chokeberry cultivars and in three cultivars derived through hybridization between chokeberry and rowans (Sorbus spp.). For each trait studied, the three black chokeberry cultivars were very similar. The three hybrid cultivars differed however from the black chokeberry cultivars for some traits in both timing and size of the response which indicates that cultivar selection for improvement of fruit quality can hardly be done among the true black chokeberry genotypes but may be efficient when the hybrid cultivars are also included. For the black chokeberry cultivars, maximum berry weight was reached already by the 22 August. Anthocyanin content increased by 180% during the period mid-August to mid-September. Meanwhile, the content of undesirable brown compounds increased by 100%. The content of malic acid remained unchanged whereas total acidity decreased in the initial part of the study period. Variation among sampling dates in total acidity was negatively correlated with variation in berry weight which suggests that dilution by water uptake affects total acidity. For the true black chokeberry cultivars, optimal harvest date was determined to be 8 September for this trial, when both mean berry weight and anthocyanin content had reached their maximum. By harvesting one week earlier browning was reduced by 32% but with a simultaneous decrease in anthocyanin content of 20%.