Biopreservation of fresh-cut pear using Lactobacillus rhamnosus GG and effect on quality and volatile compounds

In recent years, the consumption of minimally processed fruit has increased. However, unfortunately, these products could be an appropriate vehicle for the transmission of foodborne pathogens. In this study, the antagonistic capacity of the probiotic strain Lactobacillus rhamnosus GG against a cocktail of 5 serovars of Salmonella and 5 serovars of Listeria monocytogenes on fresh-cut pear at conditions simulating commercial application was assessed. Moreover, its effect on fruit quality, particularly on the volatile profile, was determined, during 9 days of storage at 5 °C. L. monocytogenes population was reduced by approximately 1.8 log-units when co-inoculated with L. rhamnosus GG. However, no effect was observed in Salmonella. Fruit quality (soluble solids content and titratable acidity) did not change when the probiotic was present. A total of 48 volatile compounds were identified using gas chromatography. Twelve of the compounds allowed to discriminate L. rhamnosus GG-treated and untreated pears. Considering their odour descriptors, their increases could be positive in the flavour perception of L. rhamnosus GG-treated pear. The probiotic was able to control L. monocytogenes population on fresh-cut pear, which could be a vehicle of probiotic microorganisms as quality of fruit was not affected when the probiotic was present.

The authors are grateful to Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya (AGAUR fellowship2015-FI-B100156 (M. Belén Iglesias)), Spanish Ministry of Science and Innovation (AGL-2012-38671 research project), European Regional Development Fund (FEDER), and CERCA Programme (Generalitat de Catalunya) for their financial support. We also thank Patricia Gálvez and Mariona Guardiola for their technical support.