Lacticaseibacillus Strains Isolated from Raw Milk: Screening Strategy for Their Qualification as Adjunct Culture in Cheesemaking

Abstract

The microbial ecology fundamentals of raw milk and long-ripened cheeses consist of a complex interaction between starter lactic acid bacteria (SLAB) and non-starter LAB (NSLAB). Although NSLAB aromatic properties are paramount, other phenotypic traits need to be considered for their use as adjunct cultures, such as the capability to endure technological parameters encountered during cheesemaking. The present study focused on the isolation and characterization of NSLAB from spontaneously fermented raw cow’s milk coming from 20 dairies that produce Grana Padano PDO cheese. From 122 isolates, the screening process selected the 10 most diverse strains belonging to Lacticaseibacillus spp. to be phenotypically characterized. The strains were tested for their growth performance in milk in combination with the application of technological stresses, for their ability to produce volatile compounds after their growth in milk, and for their ability to use different nutrient sources and resist chemicals. The complex characterization qualified the strains 5959_Lbparacasei and 5296_Lbparacasei as the best candidates to be used as adjunct strains in the production of raw milk and long-ripened cheeses, provided that antibiotic resistance is measured before their employment. Other strains with interesting aromatic capabilities but lower heat resistance were 5293_Lbparacasei, 5649_Lbparacasei and 5780_Lbparacasei, which could be candidates as adjunct strains for uncooked cheese production.

The Microbial Community of Natural Whey Starter: Why Is It a Driver for the Production of the Most Famous Italian Long-Ripened Cheeses?

“…Raw milk is a rich and very attractive substrate for different microbial species that use lactose as a carbon source. Environmental factors play crucial roles in shaping the composition of the raw milk microbiota and in defining its evolution in cheese during ripening [1,4,[6][7][8][9][10][11][12][13].…”

“…composition of the raw milk microbiota and in defining its evolution in cheese during ripening [1,4,[6][7][8][9][10][11][12][13].…”

“…For GP and PR cheese production, NWS represents a large component of the future microbiota of curd and, in collaboration with the raw milk microbiota, the "engine" of the metabolism involved in cheese making and cheese ripening [13,45]. LAB species/biotypes present in vat milk (from NWS and raw milk) can grow, survive, decline, and even become dominant during cheese manufacture.…”