Apple Bruising VI. Reducing Impact 

 Damage on Packing Lines 



William J. Bramlage 



Department of Plant & Soil Sciences, University of Massachusetts 



This is the sixth in a series of articles about apple 

 bruising, reporting results from a major program at 

 Michigan State University to identify and correct 

 sources of bruising, by far the greatest cause of 

 rejections of harvested apples and a major source of 

 lost income. The program is directed by Dr. G. K. 

 Brown and includes personnel from the MSU Agri- 

 cultural Engineering Department and the USDA 

 Agricultural Research Service. 



We previously reported results from their 1987 

 study of apple bruising during mechanical sorting 

 and packing on commercial lines [Fruit Notes 

 53(4):15-17]. That study showed that nearly every 

 apple was bruised during the operation, and that the 

 average apple was bruised 5 times. Bruising was 

 primarily caused by inadequate padding, excessive 

 apple energy at transfer points, lack of curtains and 

 brushes to slow apple movement, excessive opera- 

 tion speeds, and uneven flow of fruit through the 

 packing lines. Here are reported follow-up packing 

 line studies that have been conducted by Brown's 

 groups (Brown, G. K., N. L. Schulte Pason, E. J. 

 Timm, C. L. Burton, and D. E. Marshall. 1989. 

 Apple Packing Line Impact Damage Reduction. 

 Paper No. 89-6050, American Society of Agricultural 

 Engineers, St. Joseph, MI 49085-9659). 



Bruising During Packing Line 

 Operation 



About 20 commercial packing lines in Michigan 

 were evaluated by passing bruise-free Golden Deli- 

 cious apples through the lines and measuring result- 

 ing bruises, and by passing a "mechanical apple" 

 [Fruit Notes 54(l):6-7] through each line and meas- 

 uring impacts incurred as it passed through each 

 line. 



In this study, the average fruit sustained 4.3 

 bruises as it passed through these lines. The damage 

 was great enough so that the average fruit was 

 downgraded from U.S. Extra Fancy to U.S. No. 1 

 grade. However, the individual lines varied in their 

 destructiveness, causing from 2.3 to 5.8 bruises per 

 fruit. (One improperly run line caused 15 bruises 



per fruit and was not included in the averaging.) 



The lines had different numbers of transfer 

 points, but most had 10 or 11. The "mechanical 

 apple" showed that each transfer point can cause 

 bruising, but that they need not do so if properly 

 installed and padded. One line had 10 transfer 

 points, but only 4 caused bruising. 



Following initial evaluations, the research 

 group worked with 7 of these lines to reduce the 

 impacting occurring as apples passed through the 

 lines. Tests were then repeated and bruising was 

 compared before and after making changes. In all 

 casesbruising was reduced by the changes, although 

 it was never eliminated. (The lowest figure reached 

 was 2.3 bruises per fruit.) The reduced damage was 

 directly related to the number of transfer points that 

 were effectively padded, and the amount of energy 

 removed from each transfer. 



What Caused Bruising? 



High impacts at transfer points were always 

 caused when the "mechanical apple" hit steel, wood, 

 conveyor belting over steel or wood, or hard plastic. 

 They also sometimes resulted from hitting apples. A 

 drop of only 1/2 inch onto steel will cause a bruise of 

 nearly 1/2 inch diameter on a Golden Delicious or 

 Paulared apple. A roll down a ramp, without some 

 kind of decelerating device (e.g., a drape) before 

 hitting a hard surface, will cause a bruise equal to 

 that caused by a straight drop from that height. 



The transfer from the lift rollers or chains in the 

 water flotation tank to the drain sizer caused high 

 impacts in lines with long or steep ramps to the chain 

 sizer. The transfer into the washer caused high 

 impacts when there was a long or steep ramp into the 

 washer. Use of a transfer belt or ramp between the 

 washer and the waxer usually caused damaging 

 impacts. The transfer into the dryer caused the 

 highest impacts, because the apples directly hit the 

 steel rollers. 



Transfers into the singulator and into the sizer 

 cup caused high impacts on many lines. The singu- 

 lator impacts were due to long and steep entrance 



Fruit Notes, Winter, 1991 



