Modified over-the-row machine harvesters to improve northern highbush blueberry fresh fruit quality

Authors: WASKO-DEVETTER, LISA - Washington State University; YANG, WEI - Oregon State University; Takeda, Fumiomi; KORTHUIS, SCOTT - Oxbo International Corporation; LI, CHANGYING - University Of Georgia

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2018
Publication Date: 1/8/2019
Citation: Wasko-Devetter, L., Yang, W.Q., Takeda, F., Korthuis, S., Li, C. 2019. Modified over-the-row machine harvesters to improve northern highbush blueberry fresh fruit quality. Agriculture. https://doi.org/10.3390/agriculture9010013.
DOI: https://doi.org/10.3390/agriculture9010013

Interpretive Summary: The blueberry industry needs improved mechanical harvesting (MH) equipment that maintains fresh market quality due to rising labor costs and decreasing availability of workers for harvesting by hand. In this study, we modified a commercial over-the-row (OTR) berry harvester by replacing the hard fruit catching surface with soft materials and by replacing the rotary drum shaker with workers standing on a platform inside the OTR machine to harvest blueberries with a hand-held, air-powered mechanical shaker. Fruit firmness was highest in blueberries captured on the soft catching surface; however, the bruise incidence was higher in fruit harvested by semi-mechanical harvesting equipment. Although the study showed semi-mechanical harvesting system lowered fresh market pack-outs, and slightly increased bruise damage immediately after harvest and after 2-week cold storage, the overall fruit quality was similar to hand-harvested blueberries. The study demonstrated that fresh market quality in highbush blueberry is achievable by semi-mechanical harvesting system. This harvesting system can be developed for small- and medium-size blueberry growers.

Technical Abstract: Improved blueberry mechanical harvesting (MH) equipment that maintains fresh market quality are needed due to rising costs and decreasing availability of laborers for harvesting by hand. In 2017, a modified over-the-row (OTR) blueberry harvester prototype was used in several experiments. Modifications to the OTR harvester included: 1) removal of two rotary drum shakers (in Oregon only), 2) installation of platforms on either side from which workers harvested blueberries using hand-held pneumatic-powered shakers, and 3) on one side of the harvester, the fruit catching surface consisted of experimental soft fruit catch plates and another soft catching surface over the conveyor belt, while the other side consisted of hard, plastic catch plates and a canvas-like sheet was installed over the conveyor belt (abbreviated SCS and HCS for soft- and hard-catch surfaces, respectively). This harvesting system was used to harvest early- and early/mid-season ‘Duke’ and ‘Draper’, respectively, in Oregon, and late-season ‘Elliott’ and ‘Aurora’ in Washington. Harvested fruit were run through commercial packing lines with fresh pack out recorded and bruise incidence or fresh fruit quality evaluated during various lengths of cold storage. In Oregon, the fresh pack out for ‘Duke’ and ‘Draper’ were 83.5% and 73.2%, respectively, and no difference was noted between SCS and HCS. Initial fruit firmness of ‘Duke’ was greatest with MH with SCS followed by MH with HCS. ‘Draper’ fruit firmness was highest with hand harvesting 24 hours after harvest, followed by MH with SCS and HCS having the same firmness. After two to four weeks of cold storage, fruit firmness for both ‘Duke’ and ‘Draper’ decreased in MH fruits. For ‘Elliott’ and ‘Aurora’, fruit firmness was the same across harvesting methods. ‘Aurora’ fruit had similar bruise ratings after 24 hours between hand harvesting and MH with SCS, while ‘Elliott’ fruit showed more bruise damage by MH with both SCS and HCS than hand harvested fruit. Postharvest bruise ratings for ‘Elliott’ were not affected by harvesting method, while the bruise ratings for ‘Aurora’ were lower in hand harvested fruits compared to MH with both SCS and HCS. Although our studies showed slightly lower fresh market blueberry pack-outs, increased bruise damage, and loss of firmness in fruit harvested by the experimental MH system compared to hand harvested fruit, higher quality was achieved using SCS compared to HCS. We demonstrated that fresh market quality in northern highbush blueberry is achievable by using modified OTR harvesters with SCS and fruit removal by either hand-held pneumatic shakers or rotary drum shakers.