Brazilian law prohibits the sale of raw milk due to the risk of zoonotic diseases. Hygiene procedures during milking are crucial for ensuring the subsequent quality of the milk, which contains a variety of microorganisms ranging from those that cause spoilage to those that are potentially pathogenic. This study aimed to assess the diversity of Gram-negative bacilli in raw goat milk from municipalities in the state of Rio de Janeiro and to evaluate the formation and quantification of sessile cells in biofilms formed by these microorganisms. Eight samples of raw goat milk were collected and cultivated in selective media (VRBG, TBX, and Cetrimide). The isolates were identified using MALDI-TOF MS. Biofilm formation ability was evaluated using the Congo Red Agar (CRA) method and adhesion testing on stainless steel coupons with sessile cell counting. The 136 identified isolates indicated significant microbial diversity in raw goat milk. The CRA test revealed seven isolates that produce biofilms belonging to the genera Pseudomonas, Acinetobacter, Klebsiella , and Agrobacterium . Higher counts of sessile cells in biofilms were observed in UHT goat milk culture than in Luria-Bertani broth, indicating a high potential for microbial persistence on stainless steel surfaces in the dairy production chain. The A. radiobacter isolate exhibited the greatest biofilm formation in milk (7.46 log CFU/cm 2 ). Due to the persistence of microbial communities in milk, Good Milking Practices must be strengthened, and constant hygiene is necessary. Quantitative data on biofilm formation raises consumer awareness of the risks associated with drinking raw milk and provides valuable information on controlling biofilm formation in the production chain. Subsequent studies should evaluate these biofilms' tolerance to chemical sanitizers used in the dairy industry and analyze the kinetics of biofilm formation and removal to improve sanitation protocols.

This study was designed to investigate the effects of heat treatment and selective thiol blocking using N-ethylmaleimide (NEM) on protein partitioning during microfiltration (MF) of whey. Clarified sweet whey was subjected to five treatments: untreated control (CTRL), pH-adjusted (CTRL pH ), pH+NEM (T NEM ), pH+heat (T Heat ), and pH+NEM+heat (T NEM+Heat ). Significant differences (P<0.05) were observed in protein permeation and retention. Compared to CTRL, protein content in the permeate was 22% and 16% lower in T Heat and T NEM+Heat , respectively. Conversely, protein retention in the retentate was 22% and 16% higher in the same treatments. These results confirm that disulphide bond-mediated aggregation reduces protein permeation during MF. The findings provide new insight into how thiol reactivity and thermal treatment influence protein transmission. This scientific insight supports the development of targeted strategies (e.g., reduced- or non-thermal processing) to increase protein yield and processing sustainability in the production of value-added whey streams and whey protein ingredients.