Thermal resistance ofCronobacter sakazakiiisolated from baby food ingredients of dairy origin in liquid medium

Abstract

Milk and whey powders are commonly used ingredients in powdered infant formula (PIF) and follow-up formula (FUF). In this study, Cronobacter sakazakii and Cronobacter dublinensis both of dairy origin and a reference strain, Cronobacter muytjensii, ATCC 51329 were investigated for thermal inactivation (D and z values). Heat resistance of the pathogen was studied between 52 and 60 °C in trypic soy broth. Among the strains, C. muytjensii ATCC 51329 was the most heat-resistant strain at lower temperatures (52 and 54 °C). The D-values at 52 and 54 °C of C. muytjensii ATCC 51329 were 33.30 (±1.17) and 6.79 (±1.05) min, respectively. At higher temperatures, e.g., 56, 58, and 60 °C, C. sakazakii strains 131 and 807 exhibited the highest D values. The D-values at 56 and 58 °C were 4.73 (±0.40) min for C. sakazakii 131 and 2.30 (±0.26) min for C. sakazakii 807. The D-values at 60 °C for C. sakazakii 131 and 807 were 1.17 (±0.03) and 1.14 (±0.02) min, respectively. The z-value of the reference strain (C. muytjensii ATCC 51329) was lower than the other strains. The findings of this study will be very helpful in understanding the heat resistance of C. sakazakii and guarding against this pathogen in PIF and FUF. Practical applications The results presented will play a significant role in eliminating Cronobacter from powdered infant formula and follow-up formula and ensuring safety against this pathogen.