Weissella is a genus containing Gram-positive, heterofermentative bacteria belonging to the lactic acid bacteria (LAB) group. These bacteria are endowed with promising technological and antimicrobial attributes. Weissella cibaria W25 was isolated from a dairy environment where raw milk cheeses are produced. Therefore, we sequenced and assembled the W25 draft genome sequence, which consists of 41 contigs totaling ~2.4 Mbp, with a G + C content of 45.04%. Then we carried out a comprehensive comparative genomic analysis with W. cibaria 110, known to produce the weissellicin 110 bacteriocin, and four other non-bacteriocin-producing W. cibaria strains.

Few studies have investigated the diversity of spoilage fungi from the dairy production chain in Brazil, despite their importance as spoilage microorganisms. In the present study, 109 filamentous fungi were isolated from various spoiled dairy products and dairy production environments. The isolates were identified through sequencing of the internal transcribed spacer (ITS) region. In spoiled products, Penicillium and Cladosporium were the most frequent genera of filamentous fungi and were also present in the dairy environment, indicating that they may represent a primary source of contamination. For dairy production environments, the most frequent genera were Cladosporium, Penicillium, Aspergillus, and Nigrospora. Four species (Hypoxylon griseobrunneum, Rhinocladiella similis, Coniochaeta rosae, and Paecilomyces maximus) were identified for the first time in dairy products or in dairy production environment. Phytopathogenic genera were also detected, such as Montagnula, Clonostachys, and Riopa. One species isolated from the dairy production environment is classified as the pathogenic fungi, R. similis. Regarding the phylogeny, 14 different families were observed and most of the fungi belong to the Ascomycota phylum. The understanding of fungal biodiversity in dairy products and environment can support the development of conservation strategies to control food spoilage. This includes the suitable use of preservatives in dairy products, as well as the application of specific cleaning and sanitizing protocols designed for a specific group of target microorganisms.

Processed cheese is a dairy product with multiple end-use applications, where emulsifying salts play a fundamental role in physicochemical changes during production. Moreover, some of these salts may be a strategy to control spoilage and pathogenic microorganisms, contributing to safety and shelf life extension. This study aimed to evaluate the in vitro inhibitory activity of two emulsifying salts (ESSP = short polyP and BSLP = long polyP) against Bacillus thuringiensis CFBP 3476 and Clostridium perfringens ATCC 13124, and to compare the in situ effects of two emulsifying salts treatments (T1 = 1.5% ESSP and T2 = 1.0% ESSP + 0.5% BSLP) in processed cheeses obtained by two different methods (laboratory- and pilot-scales), during 45-day storage at 6 °C. C. perfringens ATCC 13124 growth was not affected in vitro or in situ (p > 0.05), but both of the treatments reduced B. thuringiensis CFBP 4376 counts in the tested condition. Counts of the treatments with B. thuringiensis CFBP 3476 presented a higher and faster reduction in cheeses produced by the laboratory-scale method (1.6 log cfu/g) when compared to the pilot-scale method (1.8 log cfu/g) (p < 0.05). For the first time, the inhibitory effect of emulsifying salts in processed cheeses obtained by two different methods was confirmed, and changes promoted by laboratory-scale equipment influenced important interactions between the processed cheese matrix and emulsifying salts, resulting in B. thuringiensis CFBP 4376 growth reduction.

Pseudomonas spp. são comumente relacionadas com a deterioração de produtos lácteos. Algumas espécies desse gênero, além de se multiplicarem em temperaturas de refrigeração, produzem enzimas hidrolíticas responsáveis pela deterioração do leite e seus derivados. A metaloprotease AprX é uma das proteases produzidas por Pseudomonas. Essa enzima, codificada pelo gene aprX, é resistente ao calor e capaz de manter sua atividade mesmo após tratamentos térmicos comumente utilizados na indústria de laticínios, como pasteurização e tratamento UHT (Ultra-high Temperature), resultando em perdas das características sensoriais e em problemas como a gelificação. Algumas cepas de Pseudomonas também podem produzir enzimas lipolíticas termorresistentes. Essas enzimas catalisam a hidrólise de triacilgliceróis, resultando na liberação de ácidos graxos associados à deterioração de muitos alimentos. Esses ácidos contribuem para o sabor forte, rançoso e de sabão de produtos lácteos. Em vista disso, o objetivo deste trabalho foi destacar, por meio de uma revisão de literatura, os desafios enfrentados pela indústria de lácteos frente às proteases e lipases produzidas pelo gênero Pseudomonas.

Blue discoloration caused by Pseudomonas spp. remains a recurring issue in fresh cheeses. This study evaluated gaseous ozone and ozonated mist as two distinct disinfection strategies for reducing populations of Pseudomonas paracarnis A006 on a fresh-cheese model matrix (FCMM) and assessed their effects on lipid integrity. Gaseous ozone and ozonated mist were applied at different concentrations for up to 90 min at 25 °C. Ozone treatments reduced Pseudomonas populations by up to 1.20 log CFU/g (gaseous ozone) and 1.67 log CFU/g (ozonated mist), without affecting aerobic mesophilic counts. Ozonation significantly improved color parameters associated with blue discoloration, while only minor changes in water activity were observed. Fatty acid profiles remained largely unaffected under the most intense treatments. This study provides novel evidence on the application of ozonated mist to mitigate P. paracarnis -associated blue discoloration in a high-moisture FCMM while preserving lipid integrity, highlighting ozone as a promising and sustainable intervention for fresh-cheese decontamination.