Use of a nisin-producing Lactococcus lactis strain, combined with natural antimicrobials, to improve the safety and shelf-life of minimally processed sliced apples

The intrinsic characteristics of minimally processed fruit may favor the growth of pathogens and spoilage microorganisms. In this context, the use of natural alternatives to traditional chemical sanitizer agents may represent a useful tool to increase the shelf-life and the safety of minimally processed fruit. The aim of this study was to evaluate the application of the nisin-producing Lactococcus lactis CBM21 as a potential biocontrol agent in sliced apples combined or not with hexanal, 2-(E)-hexenal and citral through microbiological, colorimetric, textural and sensory assessments. The use of L. lactis CBM21 limited the growth of yeasts on apples below 5 log cfu/g during 28 days of storage. Moreover, this strain significantly increased the safety of the products, inhibiting the growth of Listeria monocytogenes, especially when used in combination with the proposed natural antimicrobials. No negative effects on color parameters were observed after 14 days of storage in presence of the natural antimicrobials. Furthermore, the addition of the biocontrol agent was positively perceived by panelists for product flavor and odor. Even if further studies are necessary, these results suggest that the combination of the considered "hurdles" can represent a new strategy to prolong shelf-life and ensure the safety and quality of sliced apples. (C) 2015 Elsevier Ltd. All rights reserved.