Study of pulsed light inactivation and growth dynamics during storage of <i><scp>E</scp>scherichia coli </i><scp>ATCC</scp> 35218, <i><scp>L</scp>isteria innocua </i><scp>ATCC</scp> 33090, <i><scp>S</scp>almonella </i><scp>E</scp>nteritidis <scp>MA</scp>44 and <i><scp>S</scp>accharomyces cerevisiae </i><scp>KE</scp>162 and native flora in apple, orange and strawberry juices

Abstract

Summary The response of some inoculated strains and native flora to PL treatment ( X enon lamp, 3 pulses s −1 , 10 cm distance from the lamp, 71.6 J cm −2 ) in apple, orange and strawberry fresh juices with different absorbance, turbidity and particle size was investigated. Microbial growth dynamics during 12‐day storage (5 °C) of PL ‐treated juices was also evaluated. PL treatments provoked 0.3–2.6 log reductions for inoculated microorganisms and 0.1–0.7 for native flora. High turbidity and particles with high UV absorbance seemed to play a major role in the PL efficiency compared to particle size. Cold storage of PL ‐processed juices provoked an increase in S almonella Enteritidis and L isteria innocua inactivation, achieving 5.0–8.0 log reductions, while no recovery of E scherichia coli and retardation for yeast growth was observed, compared to untreated samples. This study gives valuable information regarding the influence of juice variables on PL effectiveness and emphasises the beneficial effect of a postcold storage on microbial safety of PL ‐treated juices.