Acidic components, enzyme-modified

A Romano cheese-like aroma was produced from a butter-fat emulsion by treating it with a crude enzyme mixture isolated from Candida rugosa. The emulsion consisted of 20% butterfat and 1.5% Tween 80 in a buffer solution. The treated emulsion was held at 37°C for three hours and then aged at room temperature for three days to develop the cheese-like flavor. The volatile flavor components were isolated from both the enzyme modified butterfat (EMB) and a commercial sample of Romano cheese. The flavor isolates were separated into acidic and nonacidic fractions and analyzed by gas chromatography-mass spectrometry. The results showed good correlation between the acidic fractions of the two samples. The acidic fractions contained similar relative concentrations of eight short-chain fatty acids (C2 - Cj q). Methyl ketones and esters were major components in the nonacidic fraction of the EMB. 

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-... 

Enzymes derived from the stomach of suckling calves and lambs have been found to be largely responsible for the development of characteristic flavours of Italian cheese. The properties of these enzymes (Richardson and Nelson, 1967) and the chemic nature of their activities have been studied. The development of the goaty flavour of Italian cheese, for example, is attributed to the production of low molecular weight fatty acids in milk fat, presumably induced by fat lipolysis. The production of cheese flavour components such as diacetyls and acetoin is facilitated by esterases (Magee et al., 1981). Present day cheese manufacturing practices involve the addition of external esterases to augment the production of the desired flavours. Enzyme modified cheese products are employed to fortify or intensity cheddar cheese flavour in some formulations. 

It is reasonable that the process of vesiculation occurs at an equilibrium rate, constant for each cell species and modified by the metabolic demands of the cells. We have suggested (Verity and Brown, 1968b), from maturation studies of cerebral lysosomal enzymes, that for a given rate of vesiculation, the enzyme complement of the primary lysosome is directly proportional to the individual rates of synthesis of the component enzymes. Such a hypothesis would account for the heterogeneity in acid hydrolase reaction to injury, the difference in maturation profiles of individual acid hydrolases, and the dysynchrony of acid hydrolase induction. Also suggested is a direct feedback mechanism whereby a stimulation of vesiculation may in turn induce increased enzyme synthesis, possibly through changes in membrane phospholipid metabolism. 

LDL. Low-density lipoprotein LIPASES. Lipoljitic enzymes that hydrolyze fats or fixed oils into their glycerol and fatty acid components. They are chiefly used in the dairy industry as flavor producers or modifiers and in medicine as digestive aids... 

Cycloserine (Fig- 4) is produced by several species of Streptomyces. One of the basic glycosyl components of the bacterial cell wall, n-acetyl-muramic acid (the product of Mur A and MurB), is modified by the addition of the first three amino acids sequentially by MurC, MurD and MurE enzymes. A dipeptide, D-alanyl-D-alanine is then added to make the pentapeptide. In bacteria, L-alanine is the native form and it is converted to D-alanine form by alanine racemase (Air). Two D-alanines are joined by D-ala-D-ala ligase (DdlA) to synthesize the dipeptide. Cycloserine resembles the substrate for Air and Ddl and inhibits their respective reactions in stage I of the peptidoglycan biosynthesis (Fig. 2). 

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