An extraordinary dairy phage and its properties: Occurrence, growth, inactivation, survival

Lactococcus lactis phages can be very heat resistant and phage P680 survive pasteurisation. In this work, phage growth, thermal and non-thermal as well as chemical methods were presented together and reevaluated in the elimination of P680. A fermentation failure within 2 h can occur under the presence of phage P680, which survived heating at 95 degrees C for 5 min. Up to 4 log units of reduction could be achieved using membrane filtration (cut-off 100 nm). In case of ultraviolet-C treatment, doses up to 0.05 J cm(-2) and 4 J cm(-2) were required for phage P680 to achieve 6 log units reduction in water and 8 log units reduction in filtered whey. Phage P680 was mostly resistant at pH levels of 3 and 10 (<0.5 log reduction), however, a significant drop of the phage levels was observed at pH values of 2 and 12 (similar to 6 log units of reduction). (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

Lactococcus lactis phages, specifically phage P680, have shown high heat resistance and can survive pasteurization. This study evaluated various methods, including thermal and non-thermal treatments, as well as chemical methods, to eliminate P680. Membrane filtration and ultraviolet-C treatment were effective in reducing phage P680 levels. The pH levels also affected the survival of phage P680.