Advancing “Ewiss” cheese production and strengthening its geographical identity through the use of selected autochthonous lactic and propionic acid bacteria

In response to the growing demand for product differentiation in the global dairy market, Ewiss cheese, an aged sheep milk cheese, was recently developed to enrich the portfolio of ovine cheeses produced in Sicily region (southern Italy). However, the use of commercial starter cultures does not effectively establish a strong connection between the product and its geographical origin, nor does it contribute to a distinctive identity. To address this, the present study explores the development of “Natural Ewiss” cheese (N-EC), aiming to reinforce its territorial identity through the application of selected autochthonous lactic acid bacteria (LAB) and propionic acid bacteria (PAB) as starter cultures. LAB strains of Streptococcus thermophilus from the University of Palermo culture collection were used as natural whey starter cultures, while Propioniciclava flava was introduced separately once the milk reached pH 6.4. Microbiological monitoring from milk to ripened cheese revealed a dominance of thermophilic LAB after curdling and a significant increase in PAB populations after nine months of ripening. Metagenomic analysis confirmed Streptococcus and Lactobacillus as the predominant genera throughout the ripening period. The ripened cheeses showed a protein content of 28.19% (dry matter) and a favorable fatty acid profile, notably rich in oleic acid. Volatile compound analysis identified 31 compounds, with acids, particularly propionic acid, being the most abundant. Sensory evaluations indicated that cheeses produced with indigenous strains received higher scores than those made with commercial cultures. This study demonstrates that integrating Swiss cheese-making techniques with local microbial biodiversity can enhance both the sensory qualities and the territorial identity of Ewiss cheese, thereby contributing to the preservation of regional agrifood heritage and supporting the economic sustainability of the local dairy sector.