Natural biological processes require that all plants eventually undergo senescence, death, and decomposition by microorganisms. Physical stresses, environmental factors, or disease can hasten this end in otherwise healthy plants, including species that are cultivated by humans for consumption as fresh vegetables. In this light, the trauma inflicted by harvest may be viewed as the first in a series of events that ultimately lead to decomposition. Harvest provokes physiological alterations associated with attempts to maintain homeostasis, repair injury, and prevent infection by opportunistic microorganisms. Postharvest technological interventions are applied in distribution systems for whole, fresh vegetables to delay quality changes that arise from these reactions. Unit operations applied in fresh-cut processing invariably contribute further stresses, particularly where tissues are cut or sliced. The latter operations are of critical importance, as cutting irrevocably alters metabolic processes and provides ample opportunity for invasion of tissues by microorganisms. Additional measures are therefore necessary to preserve the eating quality of fresh-cut vegetables.
Vegetables destined for fresh-cut processing carry complex microbial populations that may include saprophytic species living in mutually beneficial, symbiotic relationships with the healthy plant, potential phytopathogens, or accidental contaminants derived from environmental sources. Microorganisms derived from the field are described in detail in Chapter 1. Additional species may be acquired during subsequent handling and processing. Any or all of
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