Quality and Safety of Bovine Raw Milk : Present Challenges and Technological Solutions

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Potential of N2 gas flushing to hinder dairy-associated biofilm formation and extension

Worldwide, the dairy sector remains of vital importance for food production despite severe environmental constraints. The production and handling conditions of milk, a rich medium, promote inevitably the entrance of microbial contaminants, with notable impact on the quality and safety of raw milk and dairy products. Moreover, the persistence of high concentrations of microorganisms (especially bacteria and bacterial spores) in biofilms (BFs) present on dairy equipment or environments constitutes an additional major source of milk contamination from pre- to post-processing stages: in dairies, BFs represent a major concern regarding the risks of disease outbreaks and are often associated with significant economic losses. One consumption trend toward "raw or low-processed foods" combined with current trends in food production systems, which tend to have more automation and longer processing runs with simultaneously more stringent microbiological requirements, necessitate the implementation of new and obligatory sustainable strategies to respond to new challenges regarding food safety. Here, in light of studies, performed mainly with raw milk, that considered dominant "planktonic" conditions, we reexamine the changes triggered by cold storage alone or combined with nitrogen gas (N-2) flushing on bacterial populations and discuss how the observed benefits of the treatment could also contribute to limiting BF formation in dairies.Peer reviewe

Nitrogen gas flushing can be bactericidal: the temperature-dependent destiny of Bacillus weihenstephanensis KBAB4 under a pure N2 atmosphere

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N2 Gas-Flushing Prevents Bacteria-Promoted Lipolysis and Proteolysis and Alleviates Auto-Oxidation in Bovine Raw Milk During Cold-Storage

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Trends of Antibiotic Resistance (AR) in Mesophilic and Psychrotrophic Bacterial Populations During Cold Storage of Raw Milk, Produced by Organic and Conventional Farming Systems

chapitre numéro 4International audienc

Effect of nitrogen gas flushing treatments on total antioxidant capacity and ascorbic acid content in raw bovine milk during cold storage

Continuous nitrogen gas (N-2) flushing extends the shelf life of raw milk (RM) during cold storage. The effect of N-2 treatment on the total antioxidant capacity (TAC) and ascorbic acid (AA) content of RM was determined during cold storage. TAC of RM or deproteinized RM was determined by ABTS and DPPH methods, while L(+)-AA content of RM was determined chromatographically on days 0, 4 and 7 during storage at 6 +/- 1 degrees C. With the ABTS method, the TAC of RM decreased from 472.33 +/- 16.70 to 369.47 +/- 62.06 mu M TEAC while it reduced from 13.30 +/- 0.84 to 8.20 +/- 0.66 mu M TEAC with DPPH method during cold storage. TAC of RM determined with ABTS method decreased after 4 day-storage; however, they remained statistically similar for N-2-treated samples during 7 day-storage. The AA content of RM ranged from 14.06 to 10.76 mg/L during storage but N-2-treatment did not influence AA content significantly. Deproteinization reduced TAC values of milk samples significantly, and the reduction with the ABTS method was about 47.50 % for control samples cold-stored for four days, while it was 11.67 % for N-2-treated deproteinized RM. In conclusion, N-2-flushing through the headspace of milk containing vessels showed a significant protective effect on the antioxidant components of RM during cold storage.Peer reviewe

The extracellular phage-host interactions involved in the bacteriophage LL-H infection of Lactobacillus delbrueckii ssp. lactis ATCC 15808

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Potential of nitrogen gas (N2) flushing to extend the shelf life of cold stored pasteurized milk

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From "Viili" towards "Termoviili", a novel type of fermented milk : Characterization of growth conditions and factors for a co-culture of Lactobacillus delbrueckii and Geotrichum candidum

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Phospholipolysis Caused by Different Types of Bacterial Phospholipases During Cold Storage of Bovine Raw Milk Is Prevented by N2 Gas Flushing

Cold storage aims to preserve the quality and safety of raw milk from farms to dairies; unfortunately, low temperatures also promote the growth of psychrotrophic bacteria, some of which produce heat-stable enzymes that cause spoilage of milk or dairy products. Previously, N-2 gas flushing of raw milk has demonstrated significant potential as a method to hinder bacterial growth at both laboratory and pilot plant scales. Using a mass spectrometry-based lipidomics approach, we examined the impact of cold storage [at 6 degrees C for up to 7 days, the control condition (C)], on the relative amounts of major phospholipids (phosphatidylethanolamine/PE, phosphatidylcholine/PC, phosphatidylserine/PS, phosphatidylinositol/PI, and sphingomyelin/SM) in three bovine raw milk samples, and compared it to the condition that received additional N-2 gas flushing (N). As expected, bacterial growth was hindered by the N-2-based treatment (over 4 log-units lower at day 7) compared to the non-treated control condition. At the end of the cold storage period, the control condition (C7) revealed higher hydrolysis of PC, SM, PE, and PS (the major species reached 27.2, 26.7, 34.6, and 9.9 mu M, respectively), compared to the N-2-flushed samples (N7) (the major species reached 55.6, 35.9, 54.0, and 18.8 mu M, respectively). C7 samples also exhibited a three-fold higher phosphatidic acid (PA) content (6.8 mu M) and a five-fold higher content (17.3 mu M) of lysophospholipids (LPE, LPC, LPS, and LPI) whereas both lysophospholipids and PA remained at their initial levels for 7 days in N7 samples. Taking into consideration the significant phospholipid losses in the controls, the lipid profiling results together with the microbiological data suggest a major role of phospholipase (PLase) C (PLC) in phospholipolysis during cold storage. However, the experimental data also indicate that bacterial sphingomyelinase C, together with PLases PLD and PLA contributed to the degradation of phospholipids present in raw milk as well, and potential contributions from PLB activity cannot be excluded. Altogether, this lipidomics study highlights the beneficial effects of N-2 flushing treatment on the quality and safety of raw milk through its ability to effectively hinder phospholipolysis during cold storage.Peer reviewe