Fats, Enzyme-Modified

Enzyme-Modified Fat, 128 Enzyme-Modified Fats, (Sl)21 Enzyme-Modified Milkfat, 128 Enzyme-Modified (Source) Protein, 282 Enzyme Preparations, 129... 

Lipases (fat-cleaving enzymes) derived from mucor type moulds play an important role in the manufacturing of cheese flavour concentrates (Enzyme Modified Cheese,... 

Process flavors include processed (reaction) flavors, fat flavors, hydrolysates, autolysates, and enzyme modified flavors. Production of dairy flavor by enzyme modification of butterfat is an example (Lee et al., 1986 Manley, 1994), while meat flavor produced by enzymatic reactions has a much longer history. 

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. 

Therefore, studies on the acceleration of cheese ripening have focussed on proteolysis, especially in hard, low-moisture varieties, in particular Cheddar. Low-fat cheeses have attracted much attention recently such cheeses have poor texture and flavor and the techniques being considered to accelerate the ripening of normal cheeses are being applied to low-fat cheeses also. The third area of interest is the production of cheese-Uke products, e.g., enzyme modified cheeses, for use in the preparation of food products, e.g., processed cheeses, cheese sauces, cheese dips, etc. 

Fat-based flavors are produced by the modification of fats particularly in dairy products, like creams, butter fat, and cheese. Enzyme-modified creams are generally produced as a result of controlled lipase treatment of dairy cream. Similarly, lipases are also utilized for the manufacturing of enzyme-modified butterfat products from emulsified anhydrous butterfat. 

The use of enzymes in esterification reactions to produce industrially important products, such as emulsifiers, surfactants, wax esters, chiral molecules, biopolymers, modified fats and oils, structured lipids, and flavor esters, is well documented. The use of lipases in aqueous and nonaqueous media has found applications in organic synthesis, chiral synthesis or resolution, modification of fats and oils, and in many other fields. Moreover, lipases are highly stable even under adverse conditions such as organic solvents and high temperatures (Gandhi et al., 2000 Hari Krishna Karanth, 2002). 

Until now the most-used additives to frozen fish have been various forms of polyphosphates. These have been able to reduce drip loss, giving products containing a maximum amount of water. There is, however, a trend to reduce the application of polyphosphates in frozen fish. Other compounds, like for example polydextrose (Lanier and Akahane, 1986) or other modified polysaccharides (Sych et al., 1990) have similar effects, but the optimum situation would be to use ingredients derived from the fish itself. This could be obtained through the use of the hydrolysates mentioned. It still remains to be explained what the active components are, and what kind of profile of peptides and amino acids would be required to obtain the optimal effects. Previously a lot of work has been done in trying to manufacture fish protein hydrolysates through the combined action of enzymes and fat-extracting chemicals (Tannenbaum et al., 1974). This never became a success (Pariser et al., 1978), partly because... 

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. 

Enzymes from these organisms find numerous applications beyond PCR. Certain ones can modify plant fibers or break down proteins or fats. Heat-stable enzymes with these digestive properties are very attractive to the food processing industry. Properly controlled, their action can make prepared foods more palatable, and they can be employed where ordinary enzymes fail. In food processing, all operations must be carried out under sterile conditions. Frequently, the easiest way to maintain sterility is to keep the... 

Natural fats and oils can be used directly in products, either individually or as mixtures. In many cases, however, it is necessary to modify their properties, particularly their melting characteristics, to make them suitable for particular applications. Therefore, the oils and fats industry has developed several modification processes using enzyme technology. In particular, lipases (and lately cutinases), phospholipases and pectinases can be used for interesterification processes, ester syntheses and in olive-oil extraction. 

The properties of many dairy products, in fact their very existence, depend on the properties of milk proteins, although the fat, lactose and especially the salts, exert very significant modifying influences. Casein products are almost exclusively milk protein while the production of most cheese varieties is initiated through the specific modification of proteins by proteolytic enzymes or isoelectric precipitation. The high heat treatments to which many milk products are subjected are possible only because of the exceptionally high heat stability of the principal milk proteins, the caseins. 

Figure 2.7. The complex pathways and processes involved in fat catabolism in vertebrate tissues such as cardiac and skeletal muscles. FFAs arrive at the cell boundary either via VLDL or albumin-associated and enter the cell either by simple diffusion or through transporters. In the cytosol, FFAs are bound by FABPs, which increase the rate and amount of FFA that can be transferred to sites of utilization. Shorter chain FFAs are converted to acetylCoA in peroxisomes longer chain FFAs are directly transferred to mitochondria (via a complex system involving acylcarnitines) as long-chain acylCoA derivatives these enter the /6-oxidation spiral and are released as acetylCoA for entrance into the Krebs or citric acid cycle in the mitochondrial matrix. Fatty acid receptors (FARs) in the nucleus bind to fatty acid response elements (FAREs) and in turn regulate the production of enzymes in their own metabolism. (Modified from Veerkamp and Maatman, 1995.)...

Milk fat is valued for its pleasant flavor but its melting and rheological properties often need to be modified to make it more suitable for many food applications. The uses of milk fat can be increased by the application of various processing interventions such as fractionation, selective blending and texturization, and chemical or enzymic processes to produce speciality milk fat ingredients (Kaylegian, 1999). Most of these modification procedures... 

Sol-gel matrices can also provide a chemical surrounding that favors enzymatic reactions. Lipases act on ester bonds and are able to hydrolyze fats and oils into fatty acids and glycerol. These are interphase-active enzymes with lipophilic domains and the catalytic times reaction occurs at the water-lipid interface. Entrapped lipases can be almost 100 times more active when a chemically modified silica matrix is used. The cohydrolysis of Si(OMe)4 and RSi(OMe)3 precursors provides alkyl groups that offer a lipophihc environment that can interact with the active site of Upases and increase their catalytic activity. Such entrapped lipases are now commercially available and offer new possibilities for organic syntheses, food industry, and oil processing. ... 

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