Blue cheese flavour

A very well known dairy product is Roquefort cheese, its flavour is generated by mould action. This so called Blue cheese flavour is attributed to methyl ketones and is formed by the degradation of fatty acids by Penicillium roquefortii. The production of these bioflavours has also been investigated by our group [12,13] and will not be further discussed here. 

Enzymatic modification of milk fats with lipolytic enzymes has already been mentioned above. Besides this it is possible to manufacture complex cheese flavours today also by fermentation of raw materials of cheese processing with defined microorganisms. Roquefort and other blue cheese flavours fermented by the mould Penicil-lium Roqueforti are currently in commercial production. 

Tomasini, A., BnstiUo G., and Lebeault, J.M., Production of blue cheese flavour concentrates from different substrates supplemented with lipolyzed cream, Int. Dairy J., 5, 247, 1995. 

Lipase Triglycerides + HzO -> fatty acids + partial glycerides + glycerol Off flavours in milk flavour development in Blue cheese... 

Extensive lipolysis also occurs in Blue cheese varieties in which the principal lipase is secreted by P. roqueforti (Chapter 10). It is claimed that treatment of Blue cheese curd with PGE improves and intensifies its flavour but this practice is not widespread. Several techniques have been developed... 

Extensive lipolysis occurs in two families of cheese in which fatty acids and/or their degradation products are major contributors to flavour, i.e. certain Italian varieties (e.g. Romano and Provolone) and the Blue cheeses. Rennet paste, which contains pre-gastric esterase (PGE) rather than rennet extract, is used in the manufacture of these Italian cheeses. PGE is highly specific for the fatty acids on the sn-3 position of glycerol, which, in the case of milk lipids, are predominantly highly flavoured short-chain fatty acids (butanoic to decanoic). These acids are principally responsible for the characteristic piquant flavour of these Italian cheeses. 

Blue cheeses undergo very extensive lipolysis during ripening up to 25% of all fatty acids may be released. The principal lipase in Blue cheese is that produced by Penicillium roqueforti, with minor contributions from indigenous milk lipase and the lipases of starter and non-starter lactic acid bacteria. The free fatty acids contribute directly to the flavour of Blue cheeses but, more importantly, they undergo partial /J-oxidation to alkan-2-ones (methyl O... 

Penicillium roqueforti Yeasts Cheese flavouring (Roquefort blue cheese)... 

The formation of typical cheese flavours during natural ripening processes are not fully understood yet. The majority of reactions last for an extended time period (months) and comprise oxidative, inter- and intramolecular, enzymatic or microbial (cf. blue cheese) reactions. Substrates are partially very reactive milk-based ingredients which are mainly transformed to volatile flavour intensive compounds like esters, methylketones, aldehydes, lactones and sulphur containing products. The effect of enzymes on the flavour enhancement is also not fully understood. By variation of lipase dosage, reaction time and reaction temperature the production of different flavour notes from milk and butterfat is possible. 

Heat transforms ketoacids to methylketones like 2-heptanone, 2-nonanone with a green fatty metallic blue cheese note. Hydroxyy acids form the corresponding lactones. The creamy, buttery, coconut-like 5-decanolide, 4-dodecanolide, 5-dodecano-lide contribute to the sweet creamy buttery flavour in cream and butter. Lactose undergoes a caramelisation reaction to develop sweet, caramelic maltol and 4-hy-droxy-2,5-dimethyl-furan-3(2H)-one. Lactose and milk proteins react in a Maillard reaction to roasted, nutty, burnt notes such as 2,5-dimethyl pyrazine. 

Similar reactions following mould-induced lipolysis are responsible for the characteristic flavours of various soft and blue cheeses. 

An important but imdefined role of milk fat in the development of natural cheese flavour characteristics is well known (Law et al., 1973). Free fatty acids and presumably lipolysis of fats, play a major role in the development of desirable flavours in mould ripened cheese (Nelson, 1972). Blue cheese t)rpe flavours could be developed from mixtures of skimmed milk and homogenized cream, the homogenization favouring liberation of free fatty adds by milk lipases (Hammer and Lane, 1937). 

Some microorganisms (such as Penicillium roqueforti) decar-boxylate sorbic acid to penta-l,3-diene, which causes an off-flavour (resembling kerosene) in cheeses (Figure 11.1). The threshold concentration of penta-1,3-diene is 1 mg/kg. Also reported are cases of contaminated margarines, fruit drinks, jams and marzipan, and similar products that used pure cultures of microbial strains (such as blue cheese and fermented dairy products). 

The fungus Penicillium roqueforti is used in the production of blue-veined Roquefort, Stilton and Gorgonzola cheeses. It contributes to the flavour of these cheeses by degrading medium-chain fatty acids to methyl ketones with one less carbon atom. The fungus is also a microbial spoilage contaminant of dairy products and it is found on some mouldy grains. There are several sub-species of... 

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