Search

Bacteria can play different roles affecting flavors and food characteristics. Few studies have described the bacterial microbiota of butter. In the present paper, next-generation sequencing was used to determine bacterial diversity, together with aromatic characteristics, in raw cow milk butter processed by traditional fermentation, in fourteen small farms called “Malga”, located in the Trentino province (Alpine region, North-East of Italy). The physicochemical and aromatic characterization of traditional mountain butter (TMB) showed a low moisture level depending on the Malga producing the butter. Counts of lactic acid bacteria, Staphylococci, and coliforms, as well as diacetyl/acetoin concentrations exhibited changes according to the geographical origin of Malga and the residual humidity of butter. MiSeq Illumina data analysis revealed that the relative abundance of Lactococcus was higher in TMB samples with the highest values of acetoin (acetoin higher than 10 mg/kg). The traditional mountain butter bacterial community was characterized by a “core dominance” of psychrotrophic genera, mainly Acinetobacter and Pseudomonas, but according to ANCOM analysis, a complex bacterial population emerged and specific bacterial genera were able to characterize the TMB bacteria community, with their high abundance, based on the Malga producing the butter.

Bacteria can play different roles affecting flavors and food characteristics. Few studies have described the bacterial microbiota of butter. In the present paper, next-generation sequencing was used to determine bacterial diversity, together with aromatic characteristics, in raw cow milk butter processed by traditional fermentation, in fourteen small farms called "Malga", located in the Trentino province (Alpine region, North-East of Italy). The physicochemical and aromatic characterization of traditional mountain butter (TMB) showed a low moisture level depending on the Malga producing the butter. Counts of lactic acid bacteria, Staphylococci, and coliforms, as well as diacetyl/acetoin concentrations exhibited changes according to the geographical origin of Malga and the residual humidity of butter. MiSeq Illumina data analysis revealed that the relative abundance of Lactococcus was higher in TMB samples with the highest values of acetoin (acetoin higher than 10 mg/kg). The traditional mountain butter bacterial community was characterized by a "core dominance" of psychrotrophic genera, mainly Acinetobacter and Pseudomonas, but according to ANCOM analysis, a complex bacterial population emerged and specific bacterial genera were able to characterize the TMB bacteria community, with their high abundance, based on the Malga producing the butter. [ABSTRACT FROM AUTHOR]

In the present study, two groups of cows from a permanent lowland farm (PF) were divided during summer and reared in the PF or in a temporary alpine farm (ALP), respectively. Microbiological analyses were performed with the objective to investigate the microbial evolution of milk before, during, and after summer transhumance comparing, in particular, the two groups of cows to determine whether the alpine pasture could directly influence the milk microbiota. A significant increase of all microbial groups was registered in milk samples collected in the ALP. Interestingly, many strains belonging to species with well reported technological and probiotic activities were isolated from Alpine milk (20% Lactococcus lactis subsp. lactis/cremoris , 18% Lactobacillus paracasei , 14% Bifidobacterium crudilactis and 18% Propionibacterium sp.), whereas only 16% of strains isolated from the permanent farm milk belonged to the species Lactococcus lactis subsp. lactis/cremoris , 6% to Lactobacillus paracasei , 2% to Bifidobacterium crudilactis and 5% to Propionibacterium sp. The MiSeq Illumina data showed that Alpine milk presented a significant reduction of Pseudomonas and an increase of Lactococcus , Bifidobacterium and Lactobacillus genera. These data confirmed the practice of Alpine pasture as one of the main drivers affecting the milk microbiota. All the microbial changes disappeared when cows were delivered back from Alpine pasture to the indoor farm. • Molecular and culture techniques enabled the study of microbiota in milk samples. • Milk was sampled from 12 cows; half subjected to summer transhumance. • The Alpine pasture was the main driver affecting milk microbial composition. • Many bifidobacteria and propionibacteria were isolated from milk during transhumance. • MiSeq Illumina data confirmed significantly higher presence of bifidobacteria in Alpine milk. [ABSTRACT FROM AUTHOR]

Processing of alpine milk in malga farms is carried out under conditions that can favor contamination by coliforms, coagulase-positive staphylococci, or pathogens such as Listeria monocytogenes . With the aim to improve the hygienic characteristics and safety of cheese produced in four malga farms the use of lyophilized Natural Milk Culture prepared with selected strains was tested.. Two cheesemaking tests were carried out in the same day always starting from the same milk: in the first case following the malga recipe that uses either Natural Whey Culture or without the addition of a starter, in the second one using a Natural Milk Culture. Cheesemaking were carried out in four malga farms located in the west area of Trentino region within the same week. For hygienic and safety evaluation, aerobic colony count, coagulase-positive staphylococci, Escherichia coli , staphylococcal toxins, Listeria monocytogenes , and Salmonella spp, pH and a w were determined in raw milk from evening and morning milking, curd in vat, curd after extraction and two months-ripened cheese. Pathogens or toxins, high values of coagulase- positive staphylococci and E. coli were not found in cheese samples. However, in the curd coagulase-positive staphylococci reached values almost of 5 Log CFU/g in the two malga without starter cultures. The use of Natural Milk Culture reduced E. coli counts. In addition, DNA was extracted from cheese samples and from Natural Milk Culture and the composition of the microbial community determined by Next Generation Sequencing method. The determination of cheese microbial communities demonstrated that the use of Natural Milk Culture exerted different effects in the different malga , in any case preserving bacterial biodiversity., Competing Interests: Conflict of interest: the authors declare no potential conflict of interest.