Alexander M. Stelzleni

The United States Department of Agriculture–Food Safety Inspection Service (USDA-FSIS) performance standards require that manufacturers of fermented beef sausages validate their processes to achieve a 5-log reduction of Escherichia coli O157:H7 and Shiga toxin–producing E. coli (STEC). Most processors rely on rapid fermentation to a low pH and a mild heat treatment to achieve the lethality performance standard. However, this process alters the sensorial characteristics of traditional fermented sausages. An alternative method to achieve lethality using high-pressure processing (HPP) during the manufacture of summer sausage with higher pH (5.0) and minimal heat treatment was evaluated. Sausages inoculated with circa 9.1 log CFU/g of E. coli O157:H7 and 8.9 log CFU/g of STEC were fermented to target pH values of 4.6 or 5.0. Subsequently, fermented sausages were heated to endpoint temperatures of 54.4°C, 48.9°C, or 43.3°C to the total process treatments of (1) Process A: pH 4.6 and 54.4°C, simulated cold air chilling, (2) Process B: pH 5.0 and 54.4°C, simulated cold air chilling, (3) Process C: pH 5.0 and 54.4°C, ice bath chilling, (4) Process D: pH 5.0 and 48.9°C, ice bath chilling, and (5) Process E: pH 5.0 and 43.3°C, ice bath chilling. After processing, the product was subjected to HPP (586 MPa; 4°C±2°C) for hold times of 1, 150, or 300 s and a nontreated (no HPP) control. All treatments subjected to HPP for 150 and 300 s reduced (P≤0.05) E. coli (O157:H7 and STEC) populations by>5.0 log CFU/g and >7.5 logCFU/g, respectively. The use of HPP allows for the production of more mild beef summer sausage (pH 5.0 and a mild thermal treatment of 43.3°C) while still achieving USDA-FSIS performance standards for lethality.