ramps, hard singulator rollers, unpadded steel side- 

 walls, and excessive speed. Sizer cup impacts were 

 due to poor timing between the singulator and the 

 sizer, large gaps between the singulator and sizer 

 cups, hard sizer cups, and sometimes the absence of 

 a fabric strip to bridge the gap between singulator 

 and sizer. 



Transfer from the sizer cups to the collection 

 conveyor often caused high impacts. Some cups 

 dropped too early, others too late. Some apples hit 

 others on the conveyor, or hit against a poorly 

 padded sidewall. 



Some lines routinely operated with up to 20% of 

 the apples overflowing the singulator, dropping over 

 the side into a return belt. This occurred when there 

 was a sustained mismatch of equipment speed, a 

 temporary surge in number of fruit due to a bin of 

 small apples, or poor delivery of apples to the singu- 

 lator. In most cases, the overflow apples were 

 damaged beyond grade tolerance. 



How to Reduce Bruising? 



The authors summarize as follows. "The best 

 ways to avoid high impacts are to: minimize height 

 change, so drop energy is minimized; use decelerator 

 devices (brushes, drapes, diverters, etc.) to dissipate 

 energy and control the fruit; pad all hard surfaces to 

 spread the impact force over a large area and simul- 

 taneously absorb energy in the padding to minimize 

 rebound; and convey apples in water to absorb en- 

 ergy, achieve uniform 'sheet flow' and avoid open 

 areas on mechanical equipment where apples accel- 

 erate down ramps. Reasonable operating speeds are 

 also important. High brush speeds in washer-waxer 

 units can cause many damaging impacts between 

 apples, and can throw apples into the dryer. High 

 speeds or improper timing for singulators and sizers 

 cause the apples to undergo high impacts to enter, 



transfer, or exit these units." 



They also observed that the best way to make 90* 

 to 180° turns before waxing was in water. They 

 suggested that new lines be designed so that all 

 apples return to a water flume after inspection for 

 rots and defects and before being elevated into the 

 washer, to insure uniform flow, minimize impacts, 

 and maximize the capacity of cup sizers. They noted 

 that transfers using brushes were much gentler 

 than ones using ramps, whether or not the ramps 

 had drapes or curtains. 



Use of water flumes or water bins fillers at the 

 end of pre-sizer lines consistently caused few, if any, 

 impacts. Sponge-padded crossbars on the conveyor 

 leading to the water bin filler prevented impacts 

 during the filling operation. 



Conclusions 



It is shocking to observe the damage that occurs 

 as apples pass through the typical packing line. As 

 this study points out, sources of this damage are 

 identifiable and generally correctable. The authors 

 state, Tradition has allowed lines to be installed 

 with many of the problems found to cause bruise 

 damage." Changes can be made that will signifi- 

 cantly reduce damage, and these are usually inex- 

 pensive changes. "When installing new lines, tradi- 

 tion must be avoided if low damage is desired. 

 Manufacturers, installers, and owners can work 

 together to make low damage a reality." 



Packing line operators should carefully examine 

 their lines in light of the information presented by 

 Brown and his group. Relatively simple, inexpen- 

 sive changes can do much to reduce, if not avoid, this 

 damage. Brown's study shows that all packing lines 

 cause unnecessary apple damage, so no one can 

 afford to ignore his suggestions. 



From: Thomm. J.J. 1906. Tht American Fruit 

 Culturist. Orange Judd Company, New York. 



Fruit Notes, Winter, 1991 



