**1. Introduction**

#### **1.1 Postharvest pathogens of fruit**

Postharvest spoilage of fruits can be caused by a large number of bacterial species. Some of the most important are *Enterobacter cloacae, Erwinia herbicola*, *Lelliottia amnigena, Pantoea ananatis, Pantoea agglomerans, Pantoea allii, Enterobacter aerogenes, Pseudomonas fluorescens* and *Streptomyces* sp. [1–6]. A wide range of fungal species is similarly involved [2, 7–9].

If adequate postharvest handling and storage practices are not employed, postharvest decays of fruit and vegetables can cause losses of 50% or more [7]. The main triggers for invasion by microorganisms are physiological changes that activate ethylene synthesis or that cause changes to the cuticle or cell walls (loosening), or declines in natural antifungal compounds or high contents of carbohydrates and other nutrients and water. These changes usually occur naturally during ripening [10–12].

Postharvest contamination of fruit by human pathogens can be another key issue in the supply chain. The most commonly reported human pathogen contaminants causing disease outbreaks are bacteria such as *Escherichia coli* (*E. coli*), *Salmonella* spp., *Mycobacterium* spp., *Brucella* spp. and *Pseudomonas aeruginosa* (*P. aeruginosa*)*.* However*,* good manufacturing and handling practices can significantly reduce these contaminations [13, 14].

Because of the behavior of microbial populations, including fungi and bacteria, an initial infection may originate new infection foci that appear near the primary one, so increasing disease incidence and/or severity [15, 16]. Quality deterioration and loss of fresh fruit and vegetables during storage have an exceptionally high economic impact because by this stage high costs have been incurred in harvesting, grading, packaging, freighting and storage. All these reasons emphasize the importance of defining new practices to reduce populations of the postharvest microorganisms.
