Dairy Biofilm: Impact of Microbial Community on Raw Milk Quality


Corresponding author. TEL: 71703829; FAX: 71704329; EMAIL: moktar.hamdi@insat.rnu.tn


The aims of this study were (1) to characterize the dairy biofilm, and (2) to evaluate the impact on the raw milk quality. The ecological profile of biofilm revealed that gram-positive bacteria and fungi exhibited a significantly higher biofilm organization than gram-negative (43–64%). From 16S rDNA sequencing, microbial diversity of biofilm was constituted by Lactococcus lactis, Staphylococcus xylosus, Bacilus cereus, Candida albicans. The milk analysis in input and in output of pipelines has revealed that the rate of milk microbial community has increased to attempt 97 to 100%. The investigation of the impact of biofilm on the physicochemical properties of material has showed a decrease of hydrophobicity of stainless steel which become hydrophilic after 7 h of contact (ΔGiwi = 6.62 mJ/m2) and the increase of the electron donor character (γ = 44.8 mJ/m2). While, after 24 h of contact, results showed a decrease of the hydrophilicity degree and surface energy components of stainless steel that become hydrophobic (ΔGiwi = −56.51 mJ/m2) and lowly electron donor (γ = 2.3 mJ/m2).

Practical Applications

Dairy biofilm formation on stainless steel was investigated employing thermodynamic approach. The results revealed that the microbial adhesion on substrata was dependent on two factors: materials species and microorganisms community. These findings have important potential in the food process applicability as they suggest that the variation of surface chemistry could contribute to understand the biofilm formation to surface and also favor the protective biofilms approach on industry workshop surfaces that favors the antimicrobial coating of devices makes it simultaneously anti-adhesive and give it antimicrobial activity.