Effect of immobilized Lactobacillus casei on volatile compounds of heat treated probiotic dry-fermented sausages.

The effect of the amount of immobilized Lactobacillus casei ATCC 393 on wheat grains on the generation of volatile compounds during the production of heat treated probiotic dry-fermented sausages was investigated. For comparison reasons, sausages containing free L. casei cells or no starter culture as well as a similar commercial product were also included in the study. Samples ripened for 8 days and heat treated to 70-72°C for 8-10 min were subjected to Solid Phase Microextraction (SPME) Gas Chromatography/Mass Spectrometry (GC/MS) analysis. The starter culture affected significantly the production of volatile compounds. The highest content of esters and alcohols was observed in the sample containing 30 g of immobilized cells/kg of stuffing mixture, while the highest concentration of organic acids was observed in the sausages with no starter culture. In contrast, the commercial product contained the lowest concentration of volatiles. Principal component analysis of the semi-quantitative data revealed that the volatile composition was affected primarily by the nature and concentration of the starter culture.