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The use of natural milk culture (NMC) represents a key factor in Protected Designation of Origin (PDO) Montasio cheese, contributing to its distinctive sensory profile. The complex microbial ecosystem of NMC is the result of heat treatment and incubation conditions, which can vary considerably among different production plants. In this study, the microbiota of NMC collected from 10 PDO Montasio cheese dairies was investigated by employing colony counts and metagenomic analysis. Furthermore, residual sugars, organic acids, and volatile profiles were quantitatively investigated. Results showed that Streptococcus thermophilus was the dominant species in all NMC, and a subdominant population made of other streptococci and Ligilactobacillus salivarius was also present. The incubation temperature appeared to be the main driver of biodiversity in NMC. Metagenomics allowed us to evidence the presence of minor species involving safety (e.g., Staphylococcus aureus) as well as possible functional aspects (Next Generation Probiotics). Statistical analysis based on residual sugars, organic acids, and volatiles' content allowed to correlate the presence of specific microbial groups with metabolites of great technological and sensory relevance, which can contribute to giving value to the artisanal production procedures of NMC and clarify their role in the creation of the characteristics of PDO Montasio cheese., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The possible contribution of brine-derived microflora to the sensory attributes of cheese is still a rather unexplored field. In this study, 365 bacteria and 105 yeast strains isolated from 11 cheese brines were qualitatively tested for proteolytic and lipolytic activities, and positive strains were identified by sequencing. Among bacteria, Staphylococcus equorum was the most frequent, followed by Macrococcus caseolyticus and Corynebacterium flavescens. As for yeasts, Debaryomyces hansenii, Clavispora lusitaniae, and Torulaspora delbrueckii were most frequently identified. A total of 38% of bacteria and 59% of yeasts showed at least 1 of the metabolic activities tested, with lipolytic activity being the most widespread (81% of bacteria and 95% of yeasts). Subsequently 15 strains of bacteria and 10 yeasts were inoculated in a curd-based medium and assessed via headspace-solid phase microextraction coupled with gas chromatography-mass spectrometry to determine their volatilome. After a 30-d incubation at 12°C, most strains showed a viability increase of about 2 log cfu/mL, suggesting good adaptability to the cheese environment. A total of 26 compounds were detected in the headspace, carbonyl compounds and alcohols being the major contributors to the volatile profile of the curd-based medium. Multivariate analysis was carried out to elucidate the overall differences in volatiles produced by selected strains. Principal component analysis and hierarchical clustering analysis demonstrated that the brine-related microorganisms were separated into 3 different groups, suggesting their different abilities to produce volatile compounds. Some of the selected strains have been shown to have interesting aromatic potential and to possibly contribute to the sensory properties of cheese., (© 2023, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Recently, the Lacticaseibacillus casei group strains have been gaining growing interest due to their potential to be used as secondary adjunct cultures in cheese. This work aimed to test autochthonous Lb. casei strains as anti-blowing agents and to evaluate their impact on the evolution of the ripening and the sensory profile of Montasio cheese. The cheesemaking trial included a control production without lysozyme (C1), a control with lysozyme (C2), and four experimental productions, each containing a different pool of autochthonous Lb. casei strains (EX1-4). Samples were taken during ripening, and physicochemical, microbiological, and sensory analyses were carried out. Lb. casei counts indicate that the selected strains survived the cheesemaking and maintained their viability of about 9 log cfu g−1 at the end of the ripening. Only EX3 showed a significant slowdown of the proteolytic index compared to controls over time. Furthermore, from the principal component analysis, it emerged that at the end of the 120-day-long ripening, C2 and the experimental samples were characterized by similar profiles of volatile compounds. The late-blowing defect (LBD) was observed exclusively in C1, whereas it was not detected in the control sample with lysozyme or in any experimental samples. These findings not only confirmed the efficacy of lysozyme in preventing LBD but also supported the effectiveness of the selected Lb. casei strains as anti-blowing agents with the ability to contribute to the final volatile profile without compromising the typicality of the product. [ABSTRACT FROM AUTHOR]

The aim of the present study was to assess the ability of the packaging technology (vacuum, VAC, and modified atmosphere, MAP) to preserve the microbiological, physicochemical, and sensorial properties of already ripened and portioned PDO Italian semi-hard cheese during 120 days of storage at 8 °C. Results were compared with those obtained by analyzing the original not-packed cylindrical wheel stored at 8 °C (NP). Samples packed under MAP showed yeasts' proliferation with a final count of 4.68 Log cfu g−1, similar to that detected in the NP cheese wheels at 120 days of storage. In VAC samples yeasts did not proliferate, maintaining constant levels during time. Differently from the original wheels which showed a hardness increase in concomitant with a moisture loss during storage, packed samples under both VAC and MAP did not lose water preserving the original hardness of the product. At the same time, the packaging technology did not influence the proteolysis index in comparison to NP cheese. However, in MAP samples already at 30 days of storage different volatile compounds were produced in comparison with NP and VAC cheeses, suggesting that the modified atmosphere into the MAP pack promoted alternative microbial metabolisms and final products characterized by different volatile profiles. The study clearly demonstrated that the choice of packaging technology has an impact on the development of peculiar attributes of PDO cheeses, that are required by specific regulations in order to preserve their typicality and satisfy the consumers. • Packaging technology influenced proliferation of spoilage microorganisms • Packaged cheese preserved the initial hardness values during the whole storage time • Vacuum (VAC) and modified atmosphere (MAP) technology did not affect proteolysis • In MAP samples, different volatile compounds were produced over time • VAC was more effective than MAP in preserving the attributes of PDO Italian cheese [ABSTRACT FROM AUTHOR]