Inhibition of Cronobacter sakazakii in reconstituted infant formula using triglycerol monolaurate and its effect on the sensory properties of infant formula

Abstract Cronobacter sakazakii (C. sakazakii) is an opportunistic foodborne pathogen in infant formula. This study was designed to explore the inhibitory effect of TGML on C. sakazakii in reconstituted infant formula (RIF). Firstly, the growth curve of C. sakazakii in RIF treated by TGML and the effect of different temperatures (4, 10, 21, 30 and 37 °C), pH values (5, 6, 7, 8 and 9) and ionic strengths (25, 50, 100, 200, 400 and 800 mM) on its activity were assessed. The results showed that the inhibitory effect of TGML on C. sakazakii was dose-dependent, and 1, 2 and 5 μg/mL TGML delayed the visible growth of pathogen by 4, 12 and 24 h, respectively. Storage temperature above or below room temperature enhanced the bioactivity of TGML. And a decrease in pH also increased the antibacterial effect of TGML. However, the effect of ionic strength on its activity was not obvious. Subsequently, the antibacterial effect of TGML in physiological gastric acid and simulated gastric juice in vitro was further explored. We found that only 5 μg/mL TGML could inhibit the growth of pathogen below the infectious dose (10,000 CFU in total) in simulated gastric juice during the whole gastric emptying period (3.5–21 h), weaker than its antibacterial effect in physiological gastric acid and room temperature culture. Finally, the effect of TGML and the above environmental factors on the color and aroma of infant milk was evaluated by a 12-person panel. The results revealed that TGML did not affect the sensory flavor of milk, and the color and odor scores of infant milk under different environmental conditions did not show any significant differences. Therefore, it is concluded that TGML has a good inhibitory effect on C. sakazakii in RIF and a high sensory acceptability for consumers. Adjusting the temperature or lowering the pH enhances its bacteriostatic activity. However, the presence of infant gastric juice can impair the bioactivity of TGML. Overall, this study will provide some new ideas for controlling and eliminating the potential risk of C. sakazakii infection during infant feeding.