Flavor Formation

The flavor and taste of cured meat products are to some extent defined by ingredients such as salt, nitrite/nitrate, and spices. The overall sensory quality is influenced by the choice of process (eg, smoking), as well as by microbial activity (16,17). The aroma of fermented meat products can be divided into the volatile compounds influencing flavor and the nonvolatile compounds determining the taste of the product. In both groups can be found a number of chemical compounds such as alkanes, alkenes, aldehydes, ketones, esters, organic acids, alcohols, phenols, furanes, terpenes, aromatic compounds, and compounds containing nitrogen, sulfur, or chloride (17,18). The aroma compounds derived from decomposition of carbohydrates, lipids, and proteins can be either of endogenous or microbial origin. Microbial activity transforms carbohydrate into lactic acid via glycolysis and provides dry-cured sausages with the characteristic tangy taste. If a part of the carbohydrate is metabolized via heterofermentation, the taste and the flavor is affected by the formation of compounds such as acetic acid, formic acid, and ethanol. The initial steps in protein breakdown are primarily facilitated by the endogenous enzymes (17). The degree of proteolysis is pH-dependent. Cathepsins as well as endopeptidases, active in protein degradation, have highest activity at low pH. As regional differences in processing technologies result in sausage types varying in final pH, the aroma will differ accordingly. Bacteria are involved in the later stages of protein degradation. Breakdown of peptides is partly caused by bacteria and they are also involved in amino acid ca-tabolism (17,19). Aminopeptidase activity has been demonstrated in staphylococci and lactic acid bacteria. It is, however, remarkable that lactic acid bacteria apparently have not only a higher but also a more diverse aminopeptidase activity than staphylococci (20). The main bacterial impact on aroma lies probably in amino acid catabolism. The aldehydes 2-methylbutanal, 3-methylbutanal and 2-methylpropanal derived from branched-chained amino acids are important flavor components in dry-cured sausages (21). They can be of bacterial origin, and among starter culture strains, staphylococci seem to play a more important role than lactic acid bacteria (22). The lipids are decomposed via lipolysis and lipidoxidation. Lipolysis is caused by lipases and esterases, primarily of endogenous origin, and liberates free fatty acids of which particularly the short-chain acids affect taste. Staphylococcal lipases are reported but the activity may be limited at the conditions prevailing during fermentation and drying (23). Oxidation of fatty acids happens by chemical autoxidation or by microbial /?-oxidation. There is evidence that the latter, resulting in methylketones and methylaldehydes as well as secondary alcohols, has a significant impact on the flavor generation in dry-cured sausages (19,24). Vice versa, synthesis catalyzed by lipases should also be considered. Fragrant esters, for example, are important flavor compounds in dry-cured sausages (25). The mechanism of their formation is not known; however, their presence and significance have been connected to sausages fermented with Staphylococcus xylosus (21).

Sleeping Sanctuary

Sleeping Sanctuary

Salvation For The Sleep Deprived The Ultimate Guide To Sleeping, Napping, Resting And  Restoring Your Energy. Of the many things that we do just instinctively and do not give much  of a thought to, sleep is probably the most prominent one. Most of us sleep only because we have to. We sleep because we cannot stay awake all 24 hours in the day.

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