Design features and bruise damage evaluation of an apple harvest and infield sorting machine

Authors: POTHULA, ANAND KUMAR - US Department Of Agriculture (USDA); ZHANG, ZHAO - US Department Of Agriculture (USDA); Lu, Renfu

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2018
Publication Date: 5/1/2018
Citation: Pothula, A., Zhang, Z., Lu, R. 2018. Design features and bruise damage evaluation of an apple harvest and infield sorting machine. Transactions of the ASABE. 61(3):1135-1144.

Interpretive Summary: Apple harvest and postharvest storage and packing are labor intensive and expensive operations, which account for about 50% or more of the total production cost. An apple harvest and infield presorting prototype was developed to help growers reduce labor and production costs in harvest and postharvest storage and packing, and improve postharvest disease/pest management. The prototype uses computer vision technology, coupled with innovative designs in fruit handling and bin filling, for automatic sorting and grading of apples into processing (lower quality) and fresh market grades based on color and size at the time of harvest in the orchard. Bruise damage by impact is a critical factor in the development of the machine. This paper reports on the main design features of the prototype and experimental evaluation of bruise damage potential by the machine. An electronic impact recording device, mimicking the actual apple fruit, was used to record impacts of fruit at all critical points of the machine under both empty and partially filled bin conditions and the impact data were then analyzed for potential bruising damage to apples. In addition, more than 200 ‘Gala’ and ‘Fuji’ apples were also tested on the machine to evaluate the actual bruise damage to the test apples. Results from the electronic impact recording device showed that most impacts occurred during bin filling and the majority of the impacts recorded would not cause bruising damage to apples. The occurrence of impacts was reduced by about 60% for the partially filled bin, compared to the empty bin. Experimental evaluation of the two apple varieties showed that at least 91% of the test apples were graded as ‘Extra Fancy’ after they ran through the prototype with the partially filled bin, whereas much lower percentages of apples were graded as ‘Extra Fancy’, when the bin was empty, which suggested that the impact of apples with the floor of the wooden bin was the main cause for bruising damage to the tested apples. Hence improvements to the discharge of apples from the bin filler to the bin should be made in order to further reduce bruise damage to apples.

Technical Abstract: Infield presorting of apples, in combination with the harvest aid function, would have advantages of cost savings in postharvest handling and storage, reduced postharvest pest/disease problems, and better inventory management, while it also enhances harvest efficiency. A new apple harvest and infield presorting prototype was developed to help apple growers achieve these potential benefits. The prototype sorts and grades fruit based on color and size, using a machine vision-based sorting system with an innovative fruit singulating and rotating design (SRD), and it handles the graded fruit in the bins using newly designed automatic bin fillers. Bruise damage by impact is a critical factor in the development of the apple harvest and infield presorting prototype. This paper reports on the major design features of the prototype and experimental evaluation of the prototype for potential bruise damage. Experiments were conducted on ‘Gala’ and ‘Fuji’ apples to evaluate bruise damage potential under both empty and partially filled bin conditions. An impact recording device was used to measure the impact magnitude in terms of peak acceleration (G) at all critical points of the machine, including harvest conveyors, main conveyor, flat conveyor, SRD, cup conveyor, bin filler, and bins. It was found that bruise damage mainly occurred during bin filling. The occurrence of impacts recorded for the partially filled bin was reduced by 60%, compared to that for the empty bin, indicating that the impact between apples and the wooden bin’s floor was a major cause for bruising. The maximum G value for the partially filled bin was measured at 34.5, while the measured G values were less than 20 from start to the point just before the bin filler, indicating no bruise damage. Bruise evaluation showed that no more than 9% of the test apples would be downgraded from ‘Extra Fancy’ grade for the partially filled bin condition. Higher G values for the empty bin condition suggested the need for improvement to the discharge of apples from the bin filler to the bin so as to further reduce bruise damage.