Effects of harvest timing on maturity, fruit quality, and consumer acceptance of ‘WA 38’ apples

Timing of harvest is a critical decision for orchard management – premature or overdue picking dates can negatively affect quality traits, sensory attributes, and consumer eating experiences. Therefore, cultivars require fine-tuning in determining the optimal harvest window to guarantee the best-selling product. ‘WA 38’ is a recently released apple cultivar from Washington State University that is highly valued for its appearance, exceptional eating quality, and storage life. To ensure consumers receive high-quality fruit, it is necessary to characterize the optimal harvest time for this new cultivar. This trial focused on understanding the impacts of picking date on ‘WA 38’ maturity, pack-out, fruit quality, and consumer acceptance. A ‘WA 38’/M9-T337 block was planted in Quincy (WA, USA) in 2008 (3,036 trees ha^-1). Eight trees were harvested weekly for six consecutive weeks from September 17 to October 22, 2019. The harvest window began when the starch index averaged = 1.5 on a 1-6 scale. Yield, apple size, non-destructive maturity index (I_AD), and incidence of cull vs. marketable fruit of harvested trees were measured at each pick. Representative fruit samples were allocated for 1) instrumental fruit quality following harvest, 2) quality after 30 days of storage, 3) post-storage quality with 1 and 7 days of shelf-life, and 4) post-storage sensorial analysis for consumer preference with 1 and 7 days of shelf-life. Harvest date impacted average fruit weight, proportion of cullage, and fruit maturity (predicted by I_AD) – all parameters increased with later picks. Apple maturity across the six harvest dates was more accurately characterized by I_AD compared to starch index. The earliest picking date showed less acceptable fruit quality at harvest. The best consumer liking score at a post-storage “commercial selling date” + 7 days of shelf-life was found in apples from the second harvest (September 24, starch index 2.2 out of 6, I_AD equals 0.65).