Application of <i>Propionibacterium</i> and <i>Lactobacillus</i> Starter Cultures in Semidry Fermented and Smoked Sausage Production: Effects on Quality, Safety, and Nitrite Reduction

This study explores the functional role of <i>Propionibacterium shermanii</i> and <i>Lactobacillus acidophilus</i> as starter cultures in the development of semidry fermented and smoked sausages, with a focus on improving product quality and microbiological safety and reducing sodium nitrite levels. Four sausage formulations were prepared: one control without bacterial inoculation and three experimental groups containing different concentrations (0.08%, 0.10%, and 0.15%) of the bacterial blend. Results demonstrated that a 0.10% inoculation level achieved optimal fermentation, lowering the pH to 5.3 within 8 h and facilitating a 40% reduction in sodium nitrite without compromising color stability or safety. The inoculated samples exhibited significant improvements in water-binding and holding capacities, as well as enhanced moisture regulation and accelerated drying. Microbiological analysis revealed effective suppression of spoilage organisms and absence of <i>E. coli</i>, while organoleptic evaluation confirmed superior texture, aroma, and visual appeal in the treated groups. Colorimetric assessment showed increased pinkness and brightness values, especially in the 0.10% group. Amino acid profiling indicated a 24.2% increase in essential amino acid content, including lysine, leucine, and threonine, due to enhanced proteolysis and microbial activity. The added cultures also contributed to a significant reduction in residual nitrite levels and supported nitrosopigment formation. Storage studies confirmed the product's microbiological and physicochemical stability over 20 days under refrigeration. These findings highlight the potential of selected starter cultures as clean-label alternatives to chemical preservatives, offering a promising approach for safer, nutritionally enriched, and high-quality fermented meat products.