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Salmonella detection in probiotic products
Han Joosten1, Eva Bidlas, Nicole Garofalo
1Quality and Safety Department, Nestlé Research Centre, Vers-chez-les-Blanc, 1000 Lausanne, Switzerland. han.joosten@rdls.nestle.com
Abstract:
The presence of large amounts of probiotic bacteria in a sample may interfere with the detection of undesirable microorganisms. To illustrate this, infant formula with various strains of probiotic bacteria and the corresponding probiotic culture powders and premixes were artificially contaminated with low levels of Salmonella. Recovery of Salmonella was generally very poor when the conventional pre-enrichment procedure using buffered peptone water (BPW) was applied. However, this problem was overcome by adding antimicrobial compounds to selectively suppress the growth and/or metabolic activity of the probiotic bacteria and increasing the buffering capacity of the pre-enrichment broth. It is recommended that these analytical constraints are already addressed during the development phase of new probiotic products.
Insights
High probiotic levels can hinder pathogen detection in infant formula. Modified pre-enrichment broths with antimicrobial agents improved Salmonella recovery, crucial for food safety testing.
Area of Science:
- Food Microbiology
- Analytical Chemistry
Background:
- Probiotic bacteria are widely used in food products like infant formula.
- High concentrations of probiotics can interfere with the accurate detection of undesirable microorganisms, such as pathogens.
- Current standard methods may not effectively recover low levels of pathogens in probiotic-rich matrices.
Purpose of the Study:
- To investigate the interference of probiotic bacteria on pathogen detection in infant formula.
- To develop an improved pre-enrichment method for enhanced recovery of Salmonella in the presence of probiotics.
Main Methods:
- Infant formula, probiotic powders, and premixes were artificially contaminated with low levels of Salmonella.
- Conventional pre-enrichment using buffered peptone water (BPW) was compared with modified broths.
- Modified broths incorporated antimicrobial compounds and increased buffering capacity to suppress probiotic growth.
Main Results:
- Salmonella recovery was significantly poor using the conventional BPW pre-enrichment method.
- The modified pre-enrichment broth effectively suppressed probiotic bacteria and improved Salmonella recovery.
- The enhanced method demonstrated superior performance in complex probiotic matrices.
Conclusions:
- The presence of high probiotic loads poses a significant analytical challenge for pathogen detection.
- Modified pre-enrichment broths containing antimicrobial agents and enhanced buffering are effective solutions.
- Addressing these analytical constraints early in product development is recommended for probiotic-containing foods.
