Biomedical Engineering Reference
In-Depth Information
INCIDENCE OF ABRASION, BRUISING, COMPRESSION,
AND VIBRATION DAMAGE
Bruising can cause the browning of tissues of such fruits as apples, pears, peaches,
apricots, cherries, grapes, and bananas, resulting from enzymatic oxidation of cel-
lular contents.
24,25
Bruise damage results when the items hit each other or come in
contact with hard surfaces of machinery, containers, or handling equipment. Con-
ditions of impact that will promote bruising depend on each fruit's tissue structure.
26
Produce with dense tissue and with less air-filled interstitial space are susceptible
to deep bruises that may not be detectable on the surface and often develop into
cone-shaped and radial fractures as described among peaches
27
and potatoes.
13
On
the other hand, produce with a high volume of air-filled interstitial spaces appear to
distort in an elastic manner at the contact surface until cell breakage occurs and is
typically found in apples.
28,29
Usually the elastic region is continuously re-established
further into the fruit until all the impact energy is either dissipated during cell
breakage or stored by elastic membrane distention. The incidence of bruising in
apples during picking, bin filling, handling, and transport to the packinghouse was
reported to be between 1.46 to 2.32 bruises per fruit.
30
The lower value resulted
from gently placing the fruits in bins, handling the bins by standard fork-lift, and
transporting the bins by tri-axle fifth wheel trailer. The higher bruise value resulted
when the filled bins were hauled by a bin carrier in the orchard and transported by
truck. It was reported that 12% of apples in Korea were injured by bruising and
puncture during picking.
31
It was reported that over 95% of apples on the retail
market in Denmark are bruised,
32
while 85% of apples are reportedly bruised upon
reaching retail outlets in Korea.
31
Brown and co-workers
6
evaluated commercial
packinghouses in the 1986-87 packing season in Michigan and found that nearly
all the apples sustained bruise damage averaging over 5 bruises per fruit. Causes of
bruising were: (a) inadequate cushioning in the packing line; (b) excessive impact
at transfer points with energies estimated to be approximately 0.2 to 0.3 Joules; (c)
lack of deceleration devices (curtains made of vertical hanging belting, rubber or
fabric, and brushes to slow and control the apples); (d) excessive operating speeds
of equipment; and (e) non-uniform flow of apples. Brown and co-workers
33
studied
the packing line movement of apples using instrumented spheres (IS) to reduce
impact damage. It was found that sizing chains, steel and plastic rollers, belts, sizer
cups, and similar hard surfaces where drops exceeded 12.7 mm had impact levels
exceeding 30 g (1 g = 9.81 m/s
2
) as recorded by the IS. Pason and co-workers
29
observed that “McIntosh” apples are most sensitive to impact compared to other
varieties such as “Golden Delicious”, “Red Delicious”, and “Northern Spy”. Even
a 2-mm drop onto a steel surface can initiate bruise damage on “McIntosh” apples
one day after harvest. Bruising can also be a problem in transporting prepackaged
apples. Factors affecting bruising during transport are the quality of the road, ship-
ment distance, and type of packaging system used.
34
Peaches and pears are also susceptible to bruising by impact. Mature and older
peaches (those that have been stored) are more susceptible to impact damage and
may sustain a larger bruise volume than less mature and fresh peaches.
35
Peaches
of medium maturity should be picked to minimize damage during postharvest handling
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