Cow milk microbiota has received increased attention in recent years, not only because of its importance for human health but also because of its effect on the quality and technological properties of milk. Several studies, therefore, have investigated the effect of various production factors on the microbial composition of milk. However, most of the previous studies considered a limited number of animals from experimental or single farm, which could have biased the results. Therefore, this study aimed to understand the effect of different alpine production systems in Italy on the compositional and microbiological quality of milk, considering commercial herds with different feeding intensities and cattle breeds. The results obtained in this work indicated that the month and season of sampling (July for summer or February for winter) more than farm, breed, and cow diet exerted significant effects on cow milk parameters and microbiota. In particular, significant differences were observed for urea content in milk between sampling seasons. Differences in milk fat were mainly related to breed specific effects. From a microbiological point of view, statistically significant differences were found in presumptive lactic acid bacteria counts. Based on a culture-independent method, milk obtained in February harbored the highest number of Firmicutes (e.g., Lactobacillus) and the lowest number of Actinobacteria (e.g., Corynebacterium). Moreover, bacterial richness and diversity were higher in July during alpine pasture season indicating a significant effect of pasture feed on the growth of bacterial communities. The results of this study highlighted the effect of month or season mainly related to differences in feeding management (e.g., access to pasture during vegetation period, concentrates supplementation) on composition and microbiota in milk.

In the Trentino Alto Adige region, disposal of grape stalks (GS) represents a major cost for wineries, despite their content of phenolic and tannin-rich compounds with potential functional value in ruminant nutrition. This study evaluated whether dietary GS supplementation could influence milk microbiota and cheese quality, supporting local circular-economy strategies. GS from three red cultivars (L-GS, CS-GS, M-GS) were dried, milled, and assessed for safety; their average total polyphenol content was approximately 15 g/kg DM. 3 Holstein cows underwent a 7-week trial consisting of alternating control (CTRL) and GS-supplemented periods (2% DM). Weekly milk samples (n = 21) and corresponding mini-cheeses (n = 21) were analyzed. GS supplementation did not affect milk coliforms (2.3–2.5 log CFU/mL), while total mesophilic counts were significantly lower in M-GS (2.8 ± 0.46 log CFU/mL) than in CTRL (4.5 ± 0.71; p < 0.05). Acinetobacter dominated the milk microbiota but decreased from 34.0% in CTRL to 18.0% in L-GS. Cheese total polyphenols were highest in CS-GS (224 ± 34 mg/kg). ¹H-NMR and VOCs profiling indicated cultivar-dependent shifts in carbohydrate-related metabolites and short-chain fatty acids. Overall, GS supplementation subtly modulated cheese biochemical and aromatic traits without impairing technological performance, supporting the valorization of winery by-products within integrated dairy-viticulture systems.

Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens of concern in raw milk dairy products. Ensuring product safety requires regular own-check testing, but evidence on naturally occurring STEC behavior during aging remains limited. This study analyzed three batches of bovine raw milk washed-rind cheese produced with STEC-positive curds to evaluate: (I) STEC distribution within cheese wheels and (II) STEC behavior during aging. STEC detection followed ISO/TS 13136:2012. First, two cheese wheels from batch A were sampled at the core (n = 4) and external (n = 4) locations at three timepoints (55, 85, and 150 days after production). External regions showed higher detection rates than the core, but this pattern was inconsistent, indicating heterogeneous STEC distribution. Second, batches B (n = 25) and C (n = 24) were sampled at four timepoints (85–86, 121–122, 170–171, and 197–198 days after production). In batch B, 16/25 wheels tested positive at least once, with alternating positive/negative patterns. In batch C, no wheel remained consistently negative, and only 2/24 wheels were negative at the final timepoint. These findings highlight the heterogeneous distribution and prolonged detectability of STEC in semi-cooked bovine raw milk cheese up to 198 days of aging, emphasizing the challenges associated with STEC sampling and detection in this product.