Persistence of wild Streptococcus thermophilus strains on wooden vat and during the manufacture of a traditional Caciocavallo type cheese

Abstract

The present work was undertaken to evaluate the influence of the wooden dairy plant equipment on the microbiological characteristics of curd to be transformed into Caciocavallo Palermitano cheese. Traditional raw milk productions were performed concomitantly with standard cheese making trials carried out in stainless steel vat inoculated with a commercial starter. Milk from two different farms (A and B) was separately processed. The wooden vat was found to be a reservoir of lactic acid bacteria (LAB), while unwanted (spoilage and/or pathogenic) microorganisms were not hosted or were present at very low levels. All microbial groups were numerically different in bulk milks, showing higher levels for the farm B. LAB, especially thermophilic cocci, dominated the whole cheese making process of all productions. Undesired microorganisms decreased in number or disappeared during transformation, particularly after curd stretching. LAB were isolated from the wooden vat surface and from all dairy samples, subjected to phenotypic and genetic characterization and identification. Streptococcus thermophilus was the species found at the highest concentration in all samples analyzed and it also dominated the microbial community of the wooden vat. Fourteen other LAB species belonging to six genera (Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Streptococcus and Weissella) were also detected. All S. thermophilus isolates were genetically differentiated and a consortium of four strains persisted during the whole traditional production process. As confirmed by pH and the total acidity after the acidification step, indigenous S. thermophilus strains acted as a mixed starter culture.

Optimised method for the analysis of phenolic compounds from caper ( Capparis spinosa L.) berries and monitoring of their changes during fermentation

“…Strain differentiation was performed by random amplification of polymorphic DNA-PCR (RAPD-PCR) analysis in a 25-lL reaction mix using single primers M13, AB111 and AB106 as previously described by Settanni et al (2012). Due to the presumptive dominance of bacteria belonging to the L. plantarum group, the identification of the different strains at species level was performed by the multiplex PCR analysis based on the recA gene with species-specific primers for L. pentosus, L. plantarum and L. paraplantarum, as described by Torriani, Felis, and Dellaglio (2001).…”

Microbiological and chemical monitoring of Marsala base wine obtained by spontaneous fermentation during large-scale production

“…Recently, the request for wines with unique style is on the increase (Settanni et al 2012a). Also, the demand of special wines, such as Marsala, Porto, Madeira, and Sherry, follows this trend.…”

“…17 1987); after a long aging in a barrel, the mature Marsala wine must contains at least 17 % (v/v) ethanol. The Grillo cultivar is the grape variety mostly cultivated in Sicily to produce the base wine for Marsala (Settanni et al 2012a).…”

“…A first work on yeast ecology associated to the Grillo grapevine cultivated within the Marsala wine area was already carried out by our group (Settanni et al 2012a). Sicily represents one of the most important areas of Europe in terms of wine production, and the study of its wild yeast population could be relevant to improving the quality of its final product.…”

“…Sicily represents one of the most important areas of Europe in terms of wine production, and the study of its wild yeast population could be relevant to improving the quality of its final product. Settanni et al (2012a) also worked to select autochthonous S. cerevisiae strains with oenological aptitude for Marsala wine production. A wine starter strain collection obtained from a given area could be useful for local winemakers who want to produce wines with regional features and, at the same time, ensure the correct fermentation process.…”