“EVALUATION OF THE EFFECT OF RECONSTITUTION AND

MAINTENANCE TEMPERATURES AT 20ºC AND 30ºC ON THE

GROWTH OF Salmonella Typhimurium AND Cronobacter

sakazakii IN POWDERED INFANT FORMULA.”

UNIVERSITY AUTONOMOUS OF BARCELONAVETERINARY FACULTY

DEPARTMENT OF ANIMAL AND FOOD SCIENCE

EVA MARÍA HERNÁNDEZ QUESADASEPTEMBER 2012

INTRODUCTION

• PIF not steriles: GHP preparation &use/utilization.

• A Category (FAO/OMS): Salmonella Typhimurium &Cronobacter sakazakii.

• Infective dose & level in PIF :Microb. Criteria ✔ RECONSTITUTION

• Public Health Advisories Safety+Hygiene:Controversy T reconstitution water 70ºC.

• FAO/OMS-ESPAGHAN-AFSSA… FABRICANTES

OBJECTIVE

Controversysafety measuresfor preparation

& use.

Controversysafety measuresfor preparation

& use.

Insufficientpractice atdomesticscenario

Insufficientpractice atdomesticscenario

Severity ofinfection

Severity ofinfection

Assessment of the effect on thedevelopment of microorganismsinvolved of:- Water reconstitution

temperature- Storage temperature- PIF composition

MATERIALS & METHODS

ENUMERATION / GROWTH MODELIZATIONSTATISTICAL ANALYSIS

INCUBATION 24-72 HRS / 37°C

MICROBIOLOGICAL ANALYSIS 2-4-6-8 HRS - SPECIFIC CHROMOGENIC MEDIA

Salmonella Typhimurium CECT 772: SM2 AGAR Cronobacter sakazakii DSM 4485: ESIA AGAR

RIF STORAGE TEMPERATURE

20°C 30°C

INOCULATION OF STRAINS AT CI = 50-100 CFU/ml

Salmonella Typhimurium CECT 772 Cronobacter sakazakii DSM 4485

PIF REHYDRATION: STERILE DISTILLED WATER TEMPERATURE

20°C 30°C 40°C 50°C 60°C 70°C

FOOD MATRIX

Milk-based formula without probiotics 150 ml Milk-based formula with probiotics 150ml Soy protein-based formula 90ml

RESULTS

Salmonella Typhimurium CECT 722

Cronobacter sakazakii DSM 4485

RESULTS

RESULTS

RESULTS

RESULTS

RESULTS

RESULTS

CONCLUSIONS• Although no statistically significant difference was observed on

the growth of both bacterias due to the presence of probioticswhen comparing milk-based formulas, nutricional composition ofthe formula has definitely an effect on lag time and maximumgrowth rate for both bacteria, as for the differences observedbetween milk-based formulas and soy-based formulas, presentingboth strains higher growth rates in the former.

• The storage of the rehydrated formulas at a room temperaturesbenefits the development of both strains, especially if thereconstitution temperature is close to the optimal growth rangefor the strains studied.

CONCLUSIONS• Reconstitution at 70 °C (FAO / WHO) Major detrimental impact

on Cronobacter sakazakii and Salmonella Typhimurium,significantly reducing the risk of infection.

• Although an initial inactivation occurs with the reconstitution at60°C, depending on storage conditions, such inactivation can beexceeded by the growth, especially for Cronobacter sakazakiiDSM 4485, since it showed greater thermotolerance thanSalmonella Typhimurium CECT 722.

• Manufacturers recommendations for water T = 40-50 °C Basedon the results obtained, the risk of infection for any of the strains inany of the food matrices is not reduced.

CONCLUSIONSThus…This study indicates that long-term exposure of C. sakazakii tomild heat could enhance their survival during rehydration ofpowdered infant formula at high temperatures.

Furthermore…This study suggests that the prepared and the leftovers ofrehydrated infant formula must be stored at a refrigerationtemperature to inhibit the growth of C. sakazakii, minimizing therisk of possible outbreaks.

THANK YOUFOR YOUR ATTENTION

EVA MARÍA HERNÁNDEZ QUESADASEPTIEMBRE 2012