Title: Visual bruise assessment and analysis of mechanical impact measurement in southern highbush blueberry Authors
|Yu, P -|
|Li, C -|
|Krewers, G -|
Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 7, 2013
Publication Date: N/A
Interpretive Summary: The vast majority of the blueberry destined for the fresh market is still hand harvested. Although hand harvesting of blueberries is labor intensive and costly, the growers are not machine harvesting fruit for the fresh market because mechanical harvesters can cause excessive fruit bruising. The industry needs improved machine harvest technology and genotypes for fresh market quality fruit to reduce harvest cost and improve production efficiency. In this study, the bruise susceptibility of crisp-flesh and melting-flesh genotypes were dropped onto soft and hard surfaces from 0.5 and 1.0 m heights and assessed for flesh discoloration. Drop tests were repeated by dropping a miniature impact measurement device. The impact and velocity change data collected by the device were correlated with visual assessment data for dropped fruit. The drop tests showed that melting-flesh genotypes were more susceptible to bruising than the crisp-flesh genotypes. A bruising probability curve for each genotype was developed by correlating the blueberry bruising incidents as determined by visual assessment of dropped fruit with instrument-based measurements of impact and velocity change. The results of this study provided decision support for farmers and breeders for selecting blueberry genotypes with lower probability of developing impact bruise following machine harvest.
Technical Abstract: The United States (U.S.) is the largest blueberry producing country in the world. The majority of the highbush blueberries in the U.S.; however, is still hand-harvested because current commercial mechanical harvesters create excessive bruise damages to blueberries. The development of sensing tools for quantitative evaluation of the harvesters can assist in refining the mechanical harvesting technology. The goal of this study was to use a custom-made instrumented sphere to quantitatively evaluate three types of commercial blueberry mechanical harvesters (rotary, slapper, and sway) for potential impact points in the harvesters and severity of the impacts created by the harvesters. Our results revealed that the slapper and sway harvesters generated not only larger number of impacts but also more severe impacts than the rotary (P less than 0.05). The slapper and sway showed largely similar results in these measures. Our analysis suggested that these disparities were mostly caused by the longer agitating period, more violent shaking mechanism, and higher drop distance between the conveyer belt and the lug in the slapper and sway harvesters than in the rotary harvester.