Characterizing the microbiota of traditional wooden tools and their impact on the hygiene and quality of TAP Vastedda Palermitana cheese

This study examined the microbiota of traditional wooden tools (tina, cannara, vaciliatuma, and rotula) and their role in hygiene and quality of TAP Vastedda Palermitana cheese. Culture-dependent analyses showed that all wooden utensils harbored structured lactic acid bacteria (LAB) biofilms, with the vat showing significantly higher loads of mesophilic LAB cocci and significantly lower levels of hygiene-indicators compared with the other tools (p < 0.05). Contact between raw milk and wooden surfaces resulted in a significant enrichment of total viable counts and LAB populations (p < 0.05), without significant increases in Enterobacteriaceae or coliforms. During cheese-making, coagulation and acidification markedly increased LAB counts (p < 0.001), while the stretching step at 85-95 °C led to the almost complete elimination of undesirable bacteria, ensuring microbiological safety throughout storage. A total of 24 LAB RAPD-types were shared among wooden tools, milk, and cheese, confirming microbial transfer from equipment to product. High throughput 16S rRNA gene sequencing using the Illumina platform revealed progressive ecological selection with vat biofilms and curd dominated by streptococci and thermophilic lactobacilli, whereas the other utensils hosted more heterogeneous, environmentally influenced communities. Ripening promoted a significant shift toward Lactobacillus delbrueckii, consistent with LAB succession in stretched cheese-making. Scanning electron microscopy analysis confirmed mature, structured biofilms on all wooden tools. Physicochemical analyses showed significant changes in colour parameters and a significant increase in total polyphenol content during storage (p < 0.001), while fatty acid profiling showed a significant increase in monounsaturated fatty acids (p = 0.001) without detrimental changes in nutritional indices. Volatile organic compound analysis identified 20 aroma-active compounds. Sensory analysis revealed significant differences between TAP Vastedda Palermitana and PDO Vastedda della Valle del Belìce cheeses, with TAP exhibiting higher colour intensity and a more immediate flavour perception. Overall, traditional wooden tools contribute to the distinctive microbial, biochemical, and sensory identity of TAP Vastedda Palermitana cheese.