Causes Of Losses

Many factors contribute to losses of fresh products during postharvest handling and storage. Mechanical injury results in cuts or bruises that decrease purchase acceptability. Such damage may not be immediately evident as softening and discoloration associated with bruising takes time to develop. Thus it is frequently difficult to determine the cause of the injury and how to take corrective action.

Microbes can invade plant tissue, particularly when it has been mechanically damaged. Until recently, postharvest pathologists were primarily interested in plant pathogens present in the field or introduced during handling that lead to decay and spread from item to item within bulk containers. More recently, introduction of human pathogens by contamination from irrigation water, untreated animal manure, or association with raw meats or their exudates has led to safety concerns in fruits and vegetables that are not thoroughly washed or cooked prior to consumption (5).

As mentioned, physiological processes occur in the fruit or vegetable after detachment from the plant. Increased respiration accelerates tissue degradation and can lead to flavor development, which may be desirable in the form of ripe-fruit flavor or may be undesirable off-flavors. Excess transpiration results in shriveling, wilting, or loss of turgor causing rejection of squash, lettuce, or broccoli, and so on.

53. I. Shmulevich, N. Galili, and N. Benichou, "Development of a Nondestructive Method for Measuring the Shelf-life of Mango Fruit," Proceedings Food Processing Automation IV Conference, Chicago, 111., Nov. 3-5, 1995.

54. H. Yamamoto, M. Iwamoto, and S. Haginuma, "Nondestructive Acoustic Impulse Response Method for Measuring Internal Quality of Apples and Watermelons," Journal of the Japanese Society for Horticultural Science 50, 247-261 (1981).

55. N. Sarkar and R. R. Wolfe, "Potential of Ultrasonic Measurements in Food Quality Evaluation," Transactions of the American Society of Agricultural Engineers 26, 624-629 (1983).

56. Y. Cheng and C. G. Haugh, "Detecting Hollow Heart in Potatoes Using Ultrasound," Transactions of the American Society of Agricultural Engineers 37, 217-222 (1994).

57. B. L. Upchurch et al., "Ultrasonic Measurement for Detecting Apple Bruises," Transactions of the American Society of Agricultural Engineers 30, 803-809 (1987).

58. N. Galili, A. Mizrach, and G. Rosenhouse, Ultrasonic Testing of Whole Fruit for Nondestructive Quality Evaluation, Paper 93-6026, American Society of Agricultural Engineers, St. Joseph, Mich., 1993.

59. N. Ozer, B. Engel, and J. Simon, "Fusion Classification Techniques for Fruit Quality," Transactions of the American Society of Agricultural Engineers 38, 1927-1934 (1995).

Judith A. Abbott USDA/ARS Beltsville, Maryland

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