Volatile compounds butterfat

Forss, D. A., Dunstone, E. A. and Stark, W. 1960A. Fishy flavour in dairy products. II. The volatile compounds associated with fishy flavour in butterfat. J. Dairy Res. 27, 211-219. 

Forss, D.A., Angelini, P., Bazinet, M.L., Merritt, C. 1967. Volatile compounds produced by copper-catalysed oxidation of butterfat. J. Am. Oil. Chem. Soc. 44, 141-143. 

PAT Swoboda, KE Peers. /ra/w-4,5-Epoxyhept-trans-2-enal The major volatile compound formed by the copper and a-tocopherol induced oxidation of butterfat. J Sci Food Agric 29 803-807, 1978. 

Most of the other products found in irradiated meat volatiles except those containing sulfur or aromatic rings may also be accounted for by mechanisms associated with alkyl free radical formation in the fat. Oxygenated compounds are far less abundant than hydrocarbons, but appreciable amounts of a homologous series of n-aliphatic alcohols up to hexanol are found. Of these, only ethanol is detected in the unirradiated controls. Since the water content of meat averages nearly 60%, the formation of alcohols may be thought to occur by reaction of the alkyl free radical with water. Such a mechanism is supported by the fact that only traces of alcohols are found in irradiated dry butterfat and were undetected in irradiated triglycerides or methyl esters of fatty acids. 

Forss et al. (1960a,c) compared the qualitative and quantitative distribution of carbonyl compounds in dairy products with fishy, tallowy or painty off-flavor. Total content of volatile carbonyl compounds was approximately 10 times greater in the tallowy and 100 times greater in the painty butterfat than in fishy butterfat. Tallowy butterfat contained greater amounts of -heptanal, -octanal, -nonanal, 2-heptanone 2-heptenal and 2-nonenal, while painty butterfat contained greater amounts of K-pentanal and C5 to C10 alk-2-enals. 

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. 

Flavors and aromas commonly associated with seafoods have been intensively investigated in the past forty years ( l-7), but the chemical basis of these flavors has proven elusive and difficult to establish. Oxidized fish oils can be described as painty, rancid or cod-liver-oil like (j ), and certain volatile carbonyls arising from the autoxidation of polyunsaturated fatty acids have emerged as the principal contributors to this type of fish-like aroma ( 3, 5, 9-10). Since oxidized butterfat (9, 11-12) and oxidized soybean and linseed oils (13) also can develop similar painty, fish-like aromas, confusion has arisen over the compounds and processes that lead to fish-like aromas. Some have believed that the aromas of fish simply result from the random autoxidation of the polyunsaturated fatty acids of fish lipids (14-17). This view has often been retained because no single compound appears to exhibit an unmistakable fish aroma. Still, evidence has been developed which indicates that a relatively complex mixture of autoxidatively-derived volatiles, including the 2,4-heptadienals, the 2,4-decadienals, and the 2,4,7-decatrienals together elicit unmistakable, oxidized fish-oil aromas (3, 9, 18). Additionally, reports also suggest that contributions from (Z -4-heptenal may add characteristic notes to the cold-store flavor of certain fish, especially cod (4-5). 

Romano Cheese and Butterfat. The volatile flavor compounds were isolated from the EMB sample, a commercial sample of Romano cheese and a butterfat control sample by vacuum steam distillation. Volatiles were isolated from 2.5L EMB in five batch isolations. The EMB was mixed in a Waring blender prior to each isolation. Romano cheese was obtained from a commercial source (Stella Romano cheese, Universal Foods Corp., Milwaukee, WI). Volatiles were isolated from 700 gm Romano cheese in five batch isolations. One hundred and forty grams of cheese were cut into pieces for each isolation and slurried with 360 ml 0.1% sodium phosphate buffer solution in a blender. Volatiles were also isolated from 500 ml of butterfat emulsion control sample (207. butterfat). 

Acidic Components. The Romano cheese-like flavor of the enzyme-modified butterfat led to a study of its volatile flavor compounds. Table I lists the compounds identified, their absolute concentra-... 

Table I. Volatile Flavor Compounds Identified in the Acidic Fractions of Enzyme Modified Butterfat (EMB),...

---