Comparative study of the bacterial community of organic and conventional cow's milk

Paiva, Nuno M.L.; Ribeiro, Susana C.; Rosa, Henrique J.D.; Silva, Célia C.G.

doi:10.1016/j.fm.2024.104488

Cited by 1 publication

(1 citation statement)

References 53 publications

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“…A recently published study examined dPAB levels in the forages of 16 silage-free farms, where dPAB levels in all but one feed sample (47 samples in total) were below the limit of detection (2.0 log cfu dPAB/g feed), which is in line with the findings of previous studies on feed contamination [ 4 , 38 , 46 ]. Most other studies report conflicting results regarding the bacterial load of raw milk from organic and conventional farms but rather report a greater variation in the relative abundance of genera in organic milk or differences in the fatty acid composition of raw milk [ 48 , 49 ]. A difference in the fatty acid composition of milk was also reported by van den Oever et al [ 50 ], who compared the effect of silage and hay feeding.…”

Section: Resultsmentioning

confidence: 99%

One-Year Monitoring of Prevalence and Diversity of Dairy Propionic Acid Bacteria in Raw Milk by Means of Culture-Dependent and Culture-Independent Methods

Bücher,

Burtscher,

Zitz

et al. 2024

Foods

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Even low levels of dairy propionic acid bacteria (dPAB) can cause cheese defects, resulting in severe economic losses for the producers of selected raw milk cheeses. Therefore, routine quality control of raw cheese milk for dPAB contamination is essential if propionic acid fermentation is undesired. Although knowledge of dPAB contamination of raw milk is important to understand cheese spoilage, long-term dPAB screening data are outdated, and studies taking into account different farm management parameters and their potential influence on dPAB levels are scarce. This study aims to provide insight into the dPAB levels of raw milk over time, to identify farm management factors that potentially influence dPAB levels, and to compare a cultural yeast extract lactate agar (YELA) and lithium glycerol agar (LGA) and a culture-independent method (qPCR) for dPAB quantification with respect to their applicability in routine quality control for the dairy industry. For this purpose, bulk tank milk from 25 dairy farms was screened for dPAB contamination over a one-year period. We were able to identify significant differences in the dPAB contamination levels in raw milk depending on selected farm-specific factors and observed relationships between the different types of milking systems and dPAB contamination levels in raw milk. When dPAB were quantified by cultivation on YELA, strong overgrowth of commensal microbiota impeded counting. Therefore, we conclude that quantification on LGA or by qPCR is preferable. Both methods, colony counting on LGA as well as quantification of dPAB using qPCR, have advantages for the application in (routine) quality control of raw milk, one being low-tech and inexpensive, the other being fast and highly specific, but the detection of (low level) dPAB contamination in raw milk remains a challenge.

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