Effect of starter culture on proteolytic changes during processing of fermented beef sausages

Fermented beef sausages inoculated with four different starter cultures ( Pediococcus acidilactici, Lactobacillus curvatus, Lactobacillus sake, or Streptomyces griseus) were evaluated for proteolysis during process stages (prefermentation, fermentation, drying and heating). Increases ( p ⩽ 0.05) in the nonprotein nitrogen (NPN) fraction were found at sequential stages of processing, while starter cultures had no major effects on NPN content. Concentrations of most free amino acids increased ( p ⩽ 0.05) during fermentation and drying, and culture effects were found for differences among concentrations of some individual free amino acids. From SDS–PAGE analysis of sarcoplasmic and myofibrillar protein fractions after fermentation and drying, myosin heavy and light chains, actin and troponin were degraded during processing. However, starter culture effects were absent from SDS–PAGE protein patterns.