Cheesy flavours

Condensed milks are mostly condensed to one-third of their volume. Their composition varies somewhat, atcording to the degree of concentration and to the addition of sugar (see later). Good products should be slightly yellowish, should have no unpleasant smell or cheesy flavour and should be homogeneous and show no clots, fat drops or crystals (lactose). 

Some other cheese flavours (Provolone, Emmentaler and other miscellaneous cheesy flavour notes) can be obtained by fermentation of edible fats by means of microorganisms which are producing butter or propionic acid from these fats. 

Sodium aluminium phosphate, 5Na3P04 3AIPO4 (approximate), is also used for these purposes, since it also increases the cheesy flavour and prevents the formation of calcium phosphate crystals which can make the cheese gritty [28]. Only 1% or 2% of phosphate additives are usually needed. 

Lipase splits fatty acids from glycerol to produce free fatty acids, for example, butyric acid. If the original fat is butterfat then at low levels this produces a buttery or creamy flavour. As the free fatty acid content is increased, this strengthens the flavour to cheesy . Normally in toffees free butyric acid is not a problem at any practical level, possibly because of losses during cooking. Other free fatty acids have different flavours. Laurie acid, which is found in nuts, tastes of soap. This is not too surprising as soap often contains sodium laurate. Laurie fat sources, such as hardened palm kernel oil, are often used as a substitute for butter another potential source is nuts, which are sometimes combined with toffee. In any of these cases, lipolytic activity can shorten the shelf life of the product or render it totally unacceptable. 

Lipases release free fatty acids from milk lipids to generate a rancid, butyric, cheesy, fatty, soapy flavour. Most important are the even numbered acids C4 to C20. In cheeses from goats and sheep 4-methyl octanoic acid imparts a strong animal, goaty character. 

Alkylcarbonic acids have been separated into their enantiomers without any deriva-tization and their sequence of elution was assigned by co-injection with enantio pure references [17]. Latest results on stereoselective flavour evaluation revealed characteristic sensory properties for all the enantiomers of 2-alkylbranched acids, esters and corresponding alcohols. Tremendous differences between the mirror images of 2-methylbutanoic acid have been found. While the R-enantiomer exhibits a penetrating, cheesy-sweaty odour, the S-enantiomer emits a pleasant sweet and fine fruity note [87, 88]. All commercially available homologues of 2-methylbutanoic acid esters and 2-methylbutyl acetate are simultaneously stereoanalyzed, using heptakis (2,3-di-O-methyl-6-0-tert-butyldimethylsilyl)-P-cyclodextrin (DIME-P-CD) in PS 268 as the chiral stationary phase [88] (Eig. 6.33, Table 6.19). 

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