Integrated microbial and proteomic analysis elucidates quality degradation mechanisms of fresh milk through the...

Fresh milk quality deterioration during processing is a major dairy challenge, with microbial-driven protein degradation mechanisms unclear. This study pioneers an integrated microbiome-proteome approach to systematically elucidate the dynamic interplay between microbial succession and protein quality changes during industrial processing. Microbial community analysis revealed oscillatory richness, with 2.3-fold and 1.8-fold increases during pre-treatment (PL) and refrigerated transport (RC), respectively. Pseudomonas (12.4 % → 31.7 %) and Acinetobacter (8.1 % → 19.3 %) dominated key phases, with proteomics showing significant nutrient loss (IgM: -69.8 %; IgG: -54.15 %). Integrating microbial metagenomics with proteolytic pathway analysis identified proteases from Pseudomonas and Acinetobacter as key drivers of protein degradation (68 % activity). Pasteurization cut microbial load by 82 % but paradoxically intensified nutrient loss via protein denaturation. Crucially, our data establish a time-dependent degradation model, revealing that combined microbial enzymatic action and thermal effects account for 76 % of total protein hydrolysis, providing a theoretical framework for developing targeted intervention strategies in dairy processing optimization.