Inactivation of leuconostocs in cherimoya pulp by high hydrostatic pressure treatments applied singly or in combination with enterocin AS-48

Abstract

A cocktail of Leuconostoc mesenteroides, Leuconostoc gasicomitatum and Leuconostoc gelidum inoculated on autoclaved cherimoya pulp were treated by high hydrostatic pressure (HHP; 400, 500 or 600 MPa for 8 min) and with enterocin AS-48 (35 μg/g), singly or in combination. After treatments, samples were stored at 4 °C for 30 days or at 22 °C for 10 days. HHP treatments at 400 or 500 MPa reduced viable cell concentrations by 4.3 and 4.9 log cycles, respectively. No survivors were detected at 600 MPa. Bacteriocin addition in combination with HHP achieved an additional reduction of 0.6–0.9 log cycles after treatments at 400 or 500 MPa, and also reduced viable counts for most treatments during storage. In samples treated by HHP, regrowth of leuconostocs was delayed to days 15 (400 or 500 MPa) or 30 (600 MPa) of refrigeration storage, or day 3 at 22 °C (all treatments). Results from the study suggest that treatments at 600 MPa (8 min) can be useful to inactivate leuconostocs in cherimoya pulp.