High hydrostatic pressure inactivation of Lactobacillus plantarum cells in (O/W)-emulsions is independent from cell surface hydrophobicity and lipid phase parameters

ABSTRACT

Inactivation efficiency of high hydrostatic pressure (HHP) processing of food is strongly affected by food matrix composition. We investigated effects of fat on HHP inactivation of spoilage-associated Lactobacillus (L.) plantarum strains using defined oil-in-water (O/W)-emulsion model systems. Since fat-mediated effects on HHP inactivation could be dependent on interactions between lipid phase and microbial cells, three major factors possibly influencing such interactions were considered, that is, cell surface hydrophobicity, presence and type of surfactants, and oil droplet size. Pressure tolerance varied noticeably among L. plantarum strains and was independent of cell surface hydrophobicity. We showed that HHP inactivation of all strains tended to be more effective in presence of fat. The observation in both, surfactant-stabilized and surfactant-free (O/W)-emulsion, indicates that cell surface hydrophobicity is no intrinsic pressure resistance factor. In contrast to the presence of fat per se, surfactant type and oil droplet size did not affect inactivation efficiency.

KEYWORDS:

• High hydrostatic pressure
• fat
• emulsion
• Lactobacillus plantarum
• surface hydrophobicity
• food spoilage

Acknowledgements

We thank the providers of Lactobacillus plantarum WCFS1 (Top Institute of Nutrition (TIFN), The Netherlands), Lactobacillus plantarum P-8 (Prof. Heping Zhang, Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education, P.R. China, Inner Mongolia Agricultural University, China) and Lactobacillus plantarum strain 16 (Prof. Douwe van Sinderen, School of Microbiology & APC Microbiome Institute, University College Cork, Ireland).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Part of this work was supported by the German Ministry of Economics and Technology (via AiF) and the FEI (Forschungskreis der Ernährungsindustrie e.V. Bonn) in project AiF 17463 N.