Metataxonomic analysis of bulk tank milk and seasonal impact on starter culture development in aged goat milk cheese

The production of dairy products from goat milk has been gradually increasing worldwide. In Norway, goat milk production is seasonal, leading to variations in milk composition used for different dairy products, such as cheese. This study aimed to investigate the microbial composition of bulk tank milk and the seasonal impact on cheese microbiota development and dynamics during cheese making and ripening. Four dairy goat farms from the same geographical area were selected based on varying bulk milk somatic cell counts. Milk was collected at four different times during one lactation/season and used to produce a hard goat milk cheese from pasteurized milk. Metataxonomic analysis of milk from these four farms revealed a similar microbial composition with moderate dissimilarity between samples obtained during the spring and mating periods. Goat milk cheeses produced in different seasons exhibited varying relative abundances of Streptococcus, Lactobacillus, and Lactococcus, suggesting that milk composition influences starter culture development differently. Organic acids and total free amino acids at 6 months of ripening were significantly influenced by the starter culture composition. Our results indicate a significant seasonal effect on starter culture development in this type of cheese. Further investigations are needed to understand why and how the same bacterial strains respond differently to milk collected in different seasons and whether adjustments during cheesemaking are necessary based on the season.