Occurrence and diversity of thermophilic sporeformers in French dairy powders

Type Article
Date 2021-02
Language English
Author(s) Delaunay Louis1, Cozien Emeline2, Gehannin Pierre2, Mouhali Nassim2, Mace Sabrina2, Postollec Florence2, Leguerinel Ivan1, Mathot Anne-Gabrielle1
Affiliation(s) 1 : Université de Brest, EA3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, UMT 19.03 ALTER'iX, IBSAM, 6 rue de l’Université, 29334, Quimper, France
2 : ADRIA Food Technology Institute, UMT 19.03 ALTER'iX, Z.A. de Creac’h Gwen, 29196, Quimper Cedex, France
Source International Dairy Journal (0958-6946) (Elsevier BV), 2021-02 , Vol. 113 , P. 104889 (4p.)
DOI 10.1016/j.idairyj.2020.104889
Abstract

This study reports the prevalence of sporeforming bacteria and contamination levels of a variety of powdered dairy products from cows’, ewes’, goats’ and mares’ milk produced in France. The concentration of mesophilic spores, thermophilic spores and highly heat-resistant thermophilic spores was assessed in 61 dairy powders. Thermophilic spore concentration was highly variable between powders, likely due to the different manufacturing processes used for transforming milk into dairy powders. The different stages of processing, particularly heat treatment close to 55 °C had a strong impact on selection of thermophilic bacteria contaminating dairy powders. For some products, thermophilic spore counts were as high as 5.89 log TSC g-1. Of the 313 thermophilic isolates selected, 93.3% belonged to the species Geobacillus stearothermophilus (43.5%), Bacillus licheniformis (30.0%) and Anoxybacillus flavithermus (19.8%). These results confirm the presence of the three majority species reported worldwide.

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