Innovations in Mechanical Harvest for Cider Apples

Cider apples are predominantly harvested by hand in the U.S., and in Washington hand harvest accounts for 38%-46% of the total annual variable costs when a cider orchard is in full production. In the U.K., which is the world’s largest producer of cider, cider apples are almost exclusively harvested by machine, utilizing a shake-and-sweep system. A proof of concept study was carried out at Washington State University NWREC in Mount Vernon, to evaluate the suitability of mechanically harvesting ‘Brown Snout’ specialty cider apples utilizing a shake-and-catch system. The study assessed the impacts of harvest method and storage time on yield, fruit integrity, and juice quality characteristics. In 2011 and 2012 the harvested fruit were cold stored (0 °C) for up to 4 weeks, and in 2014 and 2015 the harvested fruit were ambient stored (average of 14 °C) for up to 4 weeks, ‘sweated’. For 2014 and 2015, the average yield (kg/ha) of the mechanical harvester was 74% that of the hand harvest yield for fruit retained by the machine and 81% when fruit that fell out of the machine were included. Under barn storage conditions, the percent of fruit lost to rot was greater for machine harvest than for hand harvest, and increased for both methods over time; percent rot doubled from 2 weeks to 4 weeks storage for machine harvest (from 22% to 41%) and while negligible, tripled during the same period for hand harvest (from 0.7% to 2.1%). The percent fruit bruised and cut were greater for machine harvest (97.5% and 25.5%, respectively) than for hand harvest (47% and 0.5%, respectively), on average for 2014 and 2015. Juice quality characteristics did not differ due to harvest method, but did differ due to storage time. Soluble solids concentration (SSC, °Brix) and specific gravity (SG) did not change due to storage in 2014, but in 2015 both were greater after storage (15.00 and 1.062 on average, respectively) than at harvest (13.31 and 1.056, respectively). pH increased in 2014 from 4.04 at harvest to 4.11 on average after storage, but there was no difference in pH in 2015. Titratable acidity (TA, malic acid g/L) decreased in 2014 from 2.98 at harvest to 2.70 on average after storage, but did not differ due to storage in 2015. Both years tannin (tannic acid %) tended to increase after storage, and on average was 0.14 at harvest and 0.16 after storage.