Effects of Maturity, Harvest Date, and Storage Time on Postharvest Quality of Red Raspberry Fruit

Abstract

Abstract ‘Meeker’ red raspberry (Rubus idaeus L.) fruit harvested at three maturity stages [inception (IN), red ripe (RR), and processing ripe (PR)] on four harvest dates at weekly intervals were held 0, 3, 6, and 9 days at 0°C and 90-95% RH. Fruit retention strength, firmness, and titratable acidity decreased with increasing maturity, while berry weight, total anthocyanin concentration, pH, and postharvest rot incidence increased. Fruit were darker visually with increasing maturity when compared to color standards. Soluble solids differences among stages of maturity were not consistent for all harvest dates. During storage, fruit at all stages of maturity increased in pH, total anthocyanin concentration, and postharvest rot incidence, but decreased in titratable acidity and darkened visually. The rate of increase in anthocyanin concentration and visual darkening was greater for IN and RR fruit than PR fruit. Total anthocyanin concentration accounted for 85% of the variation in visual darkness. Changes in red hues during storage, and differences in red hues among stages of maturity, were not consistent for all harvests and were not related to total anthocyanin concentration. Firmness increased during storage for the first harvest date, but decreased for the remaining three harvests. Berry weight, firmness, and titratable acidity decreased for all stages of maturity with later harvest dates, while postharvest rot incidence increased. This decrease in berry weight was greater for RR fruit than IN or PR fruit. Harvest date affected pH and rate of weight loss of all maturity stages and fruit retention strength of IN and RR fruit, but not PR fruit. Total anthocyanin concentration increased with later harvest dates of PR fruit, but did not change in IN or RR fruit. Soluble solids decreased linearly with harvest date in IN and PR fruit, but changed nonlinearly in RR fruit.