Cheese Comte

Musty or potato-like flavor and aroma have been observed as a defect in milk (Hammer and Babel 1957) and Gruyere de Comte cheese (Dumont et al. 1975). This off-flavor results from the production of nitrogenous cyclic compounds by Pseudomonas taetrolens and P. perolens (Morgan 1976). Musty-flavored compounds produced by these organisms include 2,5-dimethylpyrazine and 2-methoxy-3-isopropyl-pyrazine. The Gruyere de Comte with potato off-flavor contained 3-methoxy-2-propyl pyridine, as well as alkyl pyrazine compounds (Dumont et al. 1975). Murray and Whitfield (1975) postulated that alkyl pyrazines are formed in vegetables by condensation of amino acids such as valine, isoleucine, and leucine with a 2-carbon compound. Details of the synthetic mechanism in pseudomonads are unknown. 

Roudot-Algaron, F., LeBars, D., Kerhoas, L., Einhom, J., and Gripon, J.C. 1994. Phosphopeptides from Comte cheese nature and origin. J. Food Sci. 59, 544-547. 

Bouton Y, Guyot P, Grappin R (1998) Preliminary characterization of microflora of Comte cheese. J Appl Microbiol 85 123-131... 

F Roudot-Algaron, L Kerhoas, D Le Bars, J Einhorn, JC Gripon. Isolation of y-glutamyl peptides from Comte cheese. J Dairy Sci 77 1161-1166, 1994. 

Two important pathways for catecholamine metaboHsm are 0-methylation by COMT, which is cytoplasmicaHy localized, and oxidative deamination by the mitochondrial localized enzyme MAO. There are large amounts of MAO in tissues such as the fiver and the heart which are responsible for the removal of most of the circulating monoamine, including some taken in from the diet. Tyramine is found in high concentrations in certain foods such as cheese, and in wine. Normally, this tyramine is deaminated in the fiver. However, if MAO is inhibited, the tyramine may then be converted into octopamine [104-14-37] which may indirecdy cause release of NE from nerve terminals to cause hypertensive crisis. Thus MAO, which is relatively nonspecific, plays an important role in the detoxification of pharmacologically active amines ingested from the diet. 

Comte (a hard cheese made with unpasteurized cow s milk)... 

Fatty acids, both straight-chain and branched, are key contributors to the aromas of various cheeses. The presence of large amounts of propanoic acid and 3-methylbutanoic acid had been found in the odour profiles of the Emmen-tal and Comte, with the added presence of 2-methylpropanoic acid in the latter. 

The presence of 3-methylbutan-l-ol has been identified in all four samples. This compound, which is known to confer a pleasant aroma of fresh cheese, was most abundant in the Comte and Emmental. In the Emmental relatively large amounts of propan-l-ol and pentan-2-ol has been determined. The respective sweet and fresh notes that have been reported for these components may contribute to the distinctive aroma of this cheese. 

In recent works, four cheeses have been modeled to be incorporated into the thermodjmamic model fromage frais and three ripened cheese Comte, Emmental and Edam. The nature and number of functional groups used are connected with the composition of part of the molecules of the cheeses (Table 3.11). 

Table 3.11. Comte, Em mental, Edam and fromage tais average composition (in g per 100g of cheese)...

The developed models have been tested to predict the cheeses titration and sorption curves in the presence of additives eommonly used in the manufacturing or processing process of these foods (salts, acids and mixtures of salts and acids). The prediction range of the a is the same for the four cheeses (0.5-1.0), whereas the range of the pH is specific to each cheese from 4 to 10 for the Comte, 3.5-12 for the Edam, 4-11 for the Emmental and 2-12 for the fromage frais. 

Malik Melas is carrying out work on a masters on the measurement and modeling of the physical-chemical properties of cheese products (Comte, Edam, Emmental, fromage frais). 

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