This study evaluated the effect of reconstitution and storage temperatures (20°C and 30°C) on the growth of Salmonella Typhimurium and Cronobacter sakazakii in powdered infant formula. The study found that reconstituting with water at 70°C had the greatest detrimental impact on bacterial growth, while lower temperatures did not sufficiently reduce risk. Storage at room temperature benefited bacterial growth, so leftover formula must be refrigerated to inhibit growth and minimize outbreak risk.
1. “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 BARCELONA
VETERINARY FACULTY
DEPARTMENT OF ANIMAL AND FOOD SCIENCE
EVA MARÍA HERNÁNDEZ QUESADA
SEPTEMBER 2012
2. 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
3. OBJECTIVE
Controversy
safety measures
for preparation
& use.
Controversy
safety measures
for preparation
& use.
Insufficient
practice at
domestic
scenario
Insufficient
practice at
domestic
scenario
Severity of
infection
Severity of
infection
Assessment of the effect on the
development of microorganisms
involved of:
- Water reconstitution
temperature
- Storage temperature
- PIF composition
4. MATERIALS & METHODS
ENUMERATION / GROWTH MODELIZATION
STATISTICAL 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
12. CONCLUSIONS
• Although no statistically significant difference was observed on
the growth of both bacterias due to the presence of probiotics
when comparing milk-based formulas, nutricional composition of
the formula has definitely an effect on lag time and maximum
growth rate for both bacteria, as for the differences observed
between milk-based formulas and soy-based formulas, presenting
both strains higher growth rates in the former.
• The storage of the rehydrated formulas at a room temperatures
benefits the development of both strains, especially if the
reconstitution temperature is close to the optimal growth range
for the strains studied.
13. 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 at
60°C, depending on storage conditions, such inactivation can be
exceeded by the growth, especially for Cronobacter sakazakii
DSM 4485, since it showed greater thermotolerance than
Salmonella Typhimurium CECT 722.
• Manufacturers recommendations for water T = 40-50 °C Based
on the results obtained, the risk of infection for any of the strains in
any of the food matrices is not reduced.
14. CONCLUSIONS
Thus…
This study indicates that long-term exposure of C. sakazakii to
mild heat could enhance their survival during rehydration of
powdered infant formula at high temperatures.
Furthermore…
This study suggests that the prepared and the leftovers of
rehydrated infant formula must be stored at a refrigeration
temperature to inhibit the growth of C. sakazakii, minimizing the
risk of possible outbreaks.
15. THANK YOU
FOR YOUR ATTENTION
EVA MARÍA HERNÁNDEZ QUESADA
SEPTIEMBRE 2012
