J.M. Bruna

Changes in the Components of Dry-Fermented Sausages during Ripening

Several chemical changes occur during the ripening of dry-fermented sausages that determine the flavor and odor of the end product. The phenomena that take place during fermentation, that is, both acidification of the sugars by lactic acid bacteria and reduction of nitrates and nitrites to nitric oxide by micrococci have been known for several years. However, the chemical changes involved in this process, and, particularly, the agents responsible have not yet been established, although they have been attributed to changes in the majority components (proteins and lipids) and to the ingredients added (spices and condiments) in the preparation of the original mixture. The typical flavor and odor of dry-fermented sausages cannot be attributed to volatile substances alone, but to a large number of volatile and nonvolatile compounds present in the product in suitable proportions. Microbial growth in the sausage together with activity of the meat endogenous enzymes are undoubtedly partially responsible for the development of a number of aromatic and sapid compounds. However, lipid autooxidation reactions are also an important source of these substances, and it is not yet known which of these processes is more important in sausage ripening. Much research has focused on the break up of triglycerides into free fatty acids, diglycerides, and monoglycerides during ripening and the progressive increase in the amounts of different carbonyl oxidation products. Carbonyl compounds probably play a significant role in determining the flavor because, in general, these have very low perception thresholds, in the ppm and ppb range. Similarly, the protein breakdown to yield peptides and amino acids has been studied extensively, the latter being substrates of several microbial and chemical reactions that generate many flavor compounds.

The contribution of Penicillium aurantiogriseum to the volatile composition and sensory quality of dry fermented sausages.

An atoxygenic, proteolytic and lipolytic strain of Penicillium aurantiogriseum was tested for its ability to accelerate the production of volatile compounds and to improve the sensory properties of dry fermented sausages. The following batches of sausages were prepared: control; superficially inoculated with a spore suspension; added with an intracellular cell free extract; and superficially inoculated and added with the intracellular cell free extract. Higher levels of lipid oxidation products were found in the aroma extracts of sausages without a mould cover. In contrast, branched aldehydes and alcohols presented higher concentrations in superficially inoculated and extract added sausages, while esters only showed higher concentration in the first ones. The sensory analysis showed that sausages prepared with both treatments received the highest scores in all the properties evaluated, which demonstrated both the potential of this mould as producer of volatile compounds and the effectiveness of combining both treatments.

Accelerated ripening of dry fermented sausages

Abstract Research on accelerated ripening of dry fermented sausages started in the early 1990s. Fermented sausages manufacture is a very important part of meat industry in many countries and the acceleration of ripening would result in a reduction of the storage time and would increase the profit margin and the competitiveness of the end product. The different strategies that have been assayed with this purpose include ripening at elevated temperature, use of genetically modified starter bacteria, addition of enzymes and addition of slurry systems. Over the last decade, numerous studies have been carried out, especially on the addition of enzymes. The aim of this paper is to review and update the knowledge on this topic. The more recent approaches in this field, such as the use of microbial extracts, are also presented.

Use of Lactococcus lactis subsp. cremoris NCDO 763 and α-ketoglutarate to improve the sensory quality of dry fermented sausages.

The aim of the present work was to enhance the degradation of free amino acids in dry fermented sausages as precursors of volatile compounds responsible for the ripened flavour. For this purpose, Lactococcus lactis subsp. cremoris NCDO 763, its intracellular cell free extract (ICFE) and α-ketoglutarate were added to sausages. Papain was also used to increase the amount of free amino acids. When L. lactis was inoculated in sausages, an increase in the proteolytic phenomena was observed. The addition of α-ketoglutarate increased transamination phenomena in batches where it was added. The enhancement of these phenomena determined a noticeable rise in the content of glutamic acid (the main final product in transamination reactions) and a decrease, among other amino acids, of valine and leucine, with the formation of high amounts of their derivatives 2-methylpropanal and 3-methylbutanal. These aldehydes are responsible for the ripened flavour of dry fermented sausages. Sensory analysis showed an improvement of odour and flavour when L. lactis and α-ketoglutarate were combined. On the other hand, the intracellular cell free extract of L. lactis did not show any important activity in relation to amino acid breakdown even when used together with α-ketoglutarate and/or papain.