Incidence, growth and enterotoxin production of Staphylococcus aureus in insufficiently dried traditional beef ham “govedja pršuta” under different storage conditions

Market pressures for shorter product turnover and faster selling result in modified production practices of Serbian traditional dry, cured beef ham known as “govedja pršuta”. These are mainly characterized by incomplete maturation and drying of the hams, resulting in higher water activity levels of products that require correctly chosen intrinsic and extrinsic factors to control foodborne pathogens. An incidence of almost 90% has been found after the enrichment of Staphylococcus aureus in 20 tested samples produced by five different producers and marketed in different parts of Serbia. Although important these findings do not completely surprise due to known high prevalence of S. aureus. However, combined with market-driven shorter and incomplete maturation and drying of the products this high prevalence of low numbers resulted in growth and staphylococcal enterotoxin (SE) production in 35% of samples tested (7/20). Results of the analysis showed that enumerable S. aureus counts were found only in four out of twenty samples, but with counts ranging from 2.8 to 3.7 log CFU/g suggesting that actual outgrowth and toxin production perhaps occurred earlier in the production stages. Nevertheless, inoculation of enterotoxigenic isolates in the same type of product, previously found negative on the presence of S. aureus and SE, showed that both growth and SE production can occur even in the final product at 22 °C and 37 °C, but not at 12 °C, regardless of whether vacuum or aerobic packaging of the product was applied.