Contribution of a selected fungal population to the volatile compounds on dry-cured ham

Abstract

Dry-cured ham is obtained after several months of ripening. Different fungi strive on the surface, including toxigenic molds. Proteolysis and lipolysis by the endogenous and microbial enzymes seem to play a decisive role in the generation of flavor precursors in dry-cured meat products. In addition, fungi show a positive impact on the volatile compounds of ripened pork loins. However, the contribution of the fungal population to flavor formation in dry-cured ham remains unclear. One selected strain each of Penicillium chrysogenum and Debaryomyces hansenii was inoculated as starter cultures on dry-cured ham. Volatile compounds extracted by solid phase micro-extraction technique were analyzed by gas chromatography/mass spectrometry. A trained panel evaluated flavor and texture of fully ripened hams. The wild fungal population on non-inoculated control hams correlates with higher levels of short chain aliphatic carboxylic acids and their esters, branched carbonyls, branched alcohols, and some sulfur compounds, particularly at the outer muscle. Conversely, P. chrysogenum and D. hansenii seem to be responsible for higher levels of long chain aliphatic and branched hydrocarbons, furanones, long chain carboxylic acids and their esters. The very limited impact of P. chrysogenum on pyrazines in inoculated hams can be due to the activity of the yeast. Lower levels for some of the more volatile linear carbonyls at the ham surface suggest an anti-oxidant effect by micro-organisms. The differences in volatile compounds did not show a neat impact on flavor in the sensorial analysis. Nonetheless, inoculated hams got a better overall acceptability, which has to be attributed to their improved texture. The lower toughness of inoculated hams is a direct consequence of an early settling of a highly proteolytic mold. Thus, the use of selected fungi as starter cultures may be useful to obtain high-quality and safe dry-cured ham.