Effect of the wooden vats on traditional cheese characteristics

Wooden vats have been used for centuries to collect and transform milk by farmers and cheesemakers all over the world. Nowadays, the tree species mostly used to this purpose are Douglas fir and chestnut. The use of wooden vats is mandatory for the production of all PDO Sicilian cheeses, such as Ragusano, Pecorino Siciliano, Piacentinu Ennese and Vastedda della valle del Belìce. In the last years, the wooden vats have been deeply explored for the microbiological characteristics and they are covered by biofilms mainly represented by lactic acid bacteria (LAB) entrapped in a polysaccharide matrix. These microbial associations do not include pathogenic species. Up to date, there are no studies performed on the effect of wooden vats made with different tree species on the characteristics of the final cheeses. Thus, this aspect represents the main aim of the present study. Eight wooden vats (20-L volume) were made with eight tree species (Calabrian Chestnut, Sicilian Chestnut, Cedar, Cherry, Ash, Wot, Pine and Poplar) and subjected to 15-d whey treatment for the activation of the LAB biofilms on the internal surfaces. All 8 wooden vats were then used to produce PDO Vastedda della valle del Belìce cheese, according to the EU Regulation. Each cheese making (carried out in duplicate at 7-d interval) was obtained from 14 l of raw ewes’ milk. The cheeses were packaged under vacuum and, after 14 days of refrigerated storage, analysed for their physical (pH, aw, CIELab parameters) and chemical composition (DM, fat, protein, N soluble, ash, salt) according to official methods. Moreover, peroxides, TBARs and polyphenols were also determined. Vastedda cheeses were subject to a sensory evaluation following the ISO indications. Several ANOVA models were employed to statistical analyses. The results of the characterization of the cheeses revealed that the wooden vats did not influence their chemical composition, while Lightness (L*) and hue angle were significantly modified by the tree species (table 1). In particular, the cheeses produced in vats made with Calabrian and Sicilian chestnut were characterized by a lower yellow intensity than the other tree species. Poplar vat produced Vastedda cheeses with significant lower peroxidase oxidation (1.68 mq/kg) and TBARs (0.0042 mg MDA/100 g of fat), probably due to the effect of natural antioxidant transferred from the wood to the milk. No particular differences among cheeses were appreciated by the panellists.