Lipolysis, proteolysis and formation of volatile components during ripening of a fermented sausage with Pediococcus pentosaceus and Staphylococcus xylosus as starter cultures.

Bacterial growth, formation of acids, lipolysis, proteolysis, fat oxidation, formation of volatile compounds and flavour characteristics were followed during ripening and storage of a fermented sausage. The starter culture used was composed of Pediococcus pentosaceus and Staphylococcus xylosus. The number of Pediococcus sp. increased by 1.5 log cfu/g during the first day of processing and remained constant at this level for 3 weeks. The corresponding initial increase in the numbers of Staphylococcus sp., 0.4 log cfu/g, was followed by a rapid decrease in the viable numbers. Lactic acid, mainly d-lactic acid, and acetic acid were formed during ripening. The triglycerides were hydrolysed to 1,2-diglycerides and free fatty acids at the beginning of ripening, followed by the formation of 1,3-diglycerides and monoglycerides, indicating lipolytic activity. Moreover, the nonprotein nitrogen increased during ripening as a result of the proteolytic activity. Most of the changes with respect to pH, formation of d-lactic acid, acetic acid, peroxides and flavour development occurred during the initial 3 days of ripening, when growth of Pediococcus sp. and Staphylococcus sp. occurred. Lipolysis as well as proteolysis continued after this initial period. The volatile compounds identified belonged to several chemical families, viz. aliphatic and aromatic hydrocarbons, aldehydes, ketones, alcohols, phenols, carboxylic acids, esters, nitrogen compounds, sulphur compounds, chloride compounds, terpenes and furans. Many of the volatile compounds probably originated from smoke and seasoning (onion/garlic and pepper), while others were a result of the activities of muscle enzymes and bacteria.