Nonprotein Nitrogen (NPN) and Free amino acid contents of dry, fermented and nonfermented sausages

Abstract

Fermented and nonfermented sausages were analyzed for concentration changes in total and nonprotein nitrogen (NPN) and in free amino acid profiles during processing. Sausages fermented by Pediococcus pentaceous at 38°C and heated to 60°C had increases ( p < 0·05) in total N and NPN contents and increases in concentration (≥5 mg per 100 g dry sample) for 14 of 20 free amino acids. Nonfermented sausages had no increase ( p > 0·05) of NPN content and increases in only 6 of 20 free amino acids after heating to 60°C. When the effects of three starter cultures were compared, NPN concentrations after fermentation and heating and after drying were highest to lowest in the following order: P. pentaceous > P. acidilactici with M. varians > P. acidilactici. Variations of free amino acid patterns in the fermented, dried sausages were found which indicated differences in metabolic activity between the cultures. These variations did not ( p > 0·05) affect sensory scores for the dried sausages. Overall, these results for rapidly fermented and mildly heated dry sausages were similar to results previously reported for ‘European-style’ dry sausages processed with prolonged low temperature fermentations.