Raw milk microbiota modifications as affected by different cleaning procedures: The Trentingrana PDO case

Milk microbiota represents a key point in raw milk cheese production and contributes to the development of flavor and texture typical of different type of cheeses. In this context, the aim of the present study was to evaluate the influence of chlorine products usage for cleaning and sanitizing the milking equipment on i) raw milk microbiota; ii) the deriving whey-starter microbiota; and iii) Trentingrana PDO cheese microbiota volatilome.Milk samples from three farms associated to a factory producing Trentingrana PDO cheese were collected thrice weekly during a six-weeks period in which a sodium hypoclorite detergent (C) was used and in a subsequent, analogous, non-chlorine detergent period (period NC). Sampling of NC period was done after allowing a full month in the "recovery" of the microbial population; milk samples during this period (intrteval) were collected, too. Bulk milk, vat milk and whey-starter were sampled in the day immediately after collection at single farms, for a total of 96 samples. All samples were subjected to metagenomic analysis by amplification of V3-V4 regions of 16S rRNA gene and sequenced on an Illumina MiSeq platform.