bruising (85). However, a faulty washer or grader may cost the grower about 
$120 per acre besides damaging the reputation of the firm or apple area (108). 
See also (37). 
The effect of time and type of bruising is of significance in deciding 
whether to grade apples entering storage or after removal. Moving apples to 
cold storage without grading increased bruising 25 percent, but grading them 
before storage increased bruising 84 percent (117). Phillips (82) concluded 
that if apples graded out of storage were marketed immediately they could be 
handled with lower losses than if they were graded at harvest. 
Skin-punctured apples generally are regarded as culls (28). Such apples 
amounted to 0 to 2 percent in one study of the various methods of grading and 
sizing and their effect on bruising incidence (93). Hand sizing and grading 
produced the most skin punctures, but there was little or no difference among 
other methods. The story was different for other bruises occurring during 
grading and sizing. Bruises were 43 percent for hand sizing and grading and 
were 91 to 95 percent with a machine equipped with spiral rolls, singulators, 
and weight-type sizer. With the latter method, the bruises averaged 296 per 
100 fruits in one packinghouse,. 
Markwardt (67) in 1951 studied the bruising effects of various surfaces, 
sizing devices, and grading equipment. The oscillating cup and revolving wheel 
types of sizing devices showed the least amount of bruising. Chain and weight 
types showed the most. His recommendations included: (a) The use of wooden- 
roller sorters covered with one-fourth inch of firm sponge rubber; (b) use of 
a return-flow belt traveling at about 30 feet per minute; (c) a revolving-wheel 
type of sizing unit between sorter and return-flow belt; (d) no drops in eleva- 
tion that allow apples to strike one another with sufficient force to cause 
bruising; and (e) belts should be kept under tension and not backed by a hard 
surface. Green (43) suggested that handling equipment should be so designed 
that no free drops, however small, should be permitted. He reported that recon- 
stituted foam-plastic waste protected apples from bruising better than softer 
more readily deformed materials. Merchant (68) reported that bruising was 
greatest in packing plants using manual dumpers, chain eliminators, wooden 
sorting rolls, chain sizers and two-way belt accumulators. McIntosh, the second 
most important apple variety in the United States (102), is one of the most 
tender and easily bruised apples. Any packing line equipment that meets the 
requirements for McIntosh thus will be suitable for other varieties as well 
(14). 
Occasionally it is questioned whether certain size apples bruise more 
easily than others. Apple sizes 88 and 113, for instance, are often reported 
difficult to pack to prevent bruising (114). Phillips (82) found bruising was 
influenced to some extent by size of the apple. Other studies have shown that 
one size of apple may be as carefully packed as any other, but larger sizes do 
bruise more easily than smaller ones. In one study (114) size 64 apples were 
bruised three times as much as size 125. In another study (36) bruising of 
apples ranged from 43 percent for size 64 to 8.2 percent for size 150. This 
susceptibility to bruising particularly emphasizes the need to tray-pack large 
size apples especially. 
Packing Operations 
Various research reports show that packing operations may be responsible 
for from 25 to 76 percent of the bruising of apples, with the prospect of 
142 
