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Category: Applied and Industrial Microbiology
Production of Powdered Infant Formulae and Microbiological Control Measures, Page 1 of 2
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This chapter talks about infant formulae that have been included in the Commission Directives and linked to outbreaks related to the presence of Salmonella as well as of Enterobacter sakazakii and therefore need to be manufactured according to the principles i.e., according to very stringent hygiene measures. Powdered infant formulae can be subdivided into different product categories. Milk-based formulae are based on either casein or whey as the predominant source of proteins, with some of them being based on partially hydrolyzed proteins to reduce their allergenicity. The wet-mix and combined processes can be subdivided into two very distinct parts: (i) the wet part, from the reception of raw materials and ingredients up to the drying, and (ii) the dry part, from the drying up to the filling. In the dry-mix processes, all operations performed after the drying and up to the filling are exclusively dry operations. Effective monitoring plans are based on the analysis of different types of samples, reflecting the relevant elements that have an impact on the microbiological quality of the powdered infant formulae. Recommendations made by manufacturers on the safe use of the products are related to the storage and handling conditions after reconstitution of the powders.
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Example illustration of a processing line with the wet-processing and the dry-processing steps. (1) Unprocessed agricultural raw materials; (2) dissolution of processed ingredients; (3) standardization tanks; (4) clarification; (5) heat treatment (direct steam injection; CCP); (6) evaporation; (7) addition of vegetable oils (dry-mix ingredient); (8) high-pressure pumping; (9) spray drying in tower; (10) drying in after-dryer; (11) addition of vitamins (dry-mix ingredients); (12) filling. This is only an example, and different layouts and processing steps are possible (e.g., mixing and intermediate storage in the dry-processing part of the process).
Impact of improved hygiene measures on the occurrence of Salmonella in skim-milk powder (U.S. Department of Agriculture Salmonella surveillance program data); adapted from Mettler ( 1989 ).
Illustration of the fluctuations in the levels of Enterobacteriaceae in environmental samples from high-hygiene areas as a function of the presence of water. In case of an ingress of Salmonella at very low levels (which would have occurred between days 270 and 330) remaining undetected during monitoring, the presence of water would invariably lead to an increase of the pathogen, putting the production lines and the product at risk (a hypothetical example is used for illustration).
Evolution of the levels of environmental Enterobacteriaceae following the implementation of the stringent hygiene measures described in the text at around the fourth month. The target level is <10 CFU/g. Values of >10 CFU/g, <100 CFU/g, and >100 CFU/g automatically trigger an increase of the testing frequency of finished product for both E. sakazakii and other Enterobacteriaceae. The question mark in the key at upper left indicates “>” (greater than).
Comparison of the mean concentrations of Enterobacteriaceae (EB) (90% credibility interval) in powdered infant formulae manufactured in five different factories before (2002) and after (2004) the introduction of the more stringent control measures described in the text.
Evolution of the levels of environmental Enterobacteriaceae in processing environments in a factory switching from the production of powdered infant formulae to other dry dairy products with different microbiological requirements (Enterobacteriaceae must be absent from 1-g samples) but equivalent requirements for Salmonella. The key at upper right indicates numbers per gram.
Estimates of the worldwide production of infant formula
Number of positive samples in three major dry-mix ingredients and illustration of the improvements over 2 to 3 years
Current situation (2007) with respect to microbiological criteria for infant formulae at Codex Alimentarius and EC levels c