Extracts of vegetation waste water from olive milling against pomegranate postharvest pathogens.

Pomegranate (Punica granatum L.) is a deciduos shrub widely grown in many tropical and subtropical regions, including Mediterranean countries. Its cultivation is rapidly expanding also in southern Italy. The nonclimateric fruits are harvested at full ripening when the organoleptic and nutritional values, but also the susceptibility to pathogen attacks, are the highest. Botrytis cinerea and Penicillium spp. are the most important postharvest pathogens. These pathogens can be contained by a widely used fludioxonolil-based postharvest treatment the use of which is not allowed in Italy. In the present investigation, a phenolic concentrate obtained from olive mill wastewater (COMW) through a membrane filtration process and a related purificate (PCOMW) deprived of the sugar were produced and in-vitro tested against an isolate of B. cinerea and one of Penicillium spp. obtained from decayed pomegranates. At the dose of 4 and 8 mg ml-1 phenols both COMW and PCOMW significantly reduced the growth of Penicillium sp. while only PCOMW at the dose of 8 mg ml -1 phenols significantly reduced the growth of B. cinerea , suggesting a different effect of both phenolic and sugar component on the pathogen growth. Treatments significantly reduced also conidia germination and germ tube elongation of both pathogens. These preliminary results suggest the possible use of COMW and PCOMW for postharvest treatment of pomegranate. These products could represent an health- and environmental-safe alternative to pesticides and an alternative way of utilization of olive mill wastewater, whose high content of phenols determines serious disposal problems.