Lipolysis, cheese ripening

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... 

Contents I. Introduction 168 II. Sampling Techniques 168 III. Compositional Analysis 169 A. Moisture and total solids 169 B. Fat 171 C. Protein 171 D. Ash 172 E. Salt and chloride content 172 F. Acidity and pH 172 G. Calcium and phosphorus 173 IV. Monitoring Cheese Ripening 173 A. Assessment of lactose, lactate, and citrate metabolism 174 B. Assessment of lipolysis 178 C. Assessment of proteolysis 180 D. Assessment of smaller breakdown products 194 V. Novel and Rapid Instrumental Methods 196 VI. Concluding Remarks 200 References 201... 

Lipolysis is considered to be an important biochemical event during cheese ripening and the current knowledge have been discussed in detail (Collins et al., 2003, 2004 McSweeney and Sousa, 2000). The formation of short-chain FFAs by the lipolysis of milk fat by lipases is a desirable reaction in many cheese types (e.g., mold-ripened cheeses). The catabolism of FFAs, which is a secondary event in the ripening process, leads to the formation of volatile flavor compounds such as lactones, thioesters, ethyl esters, alkanols, and hydroxyl fatty acids. The contributions of lipolysis to the flavor of bacterially ripened cheeses are limited. 

Salji, J. P. and Kroger, M. (1981). Proteolysis and lipolysis in ripening Cheddar cheese made with conventional bulk starter and with frozen concentrated direct-to-the-vat starter culture. ]. Food Sci. 46,1345-1348. 

Both proteolysis and lipolysis are involved in the cheese ripening process. The rate and extent of their interactions are influenced by the rennet preparation used, characteristics of the starter culture, pH, moisture range, salting practices, temperature, and the activity of adventitious microorganisms present in or on the cheese. 

Other nonstarter bacteria (e.g.. Micrococcus and Pediococcus) also produce lipases. It is generally believed that lipases from Micrococcus spp., when present in cheese, can contribute to lipolysis during ripening (Bhow-mik and Marth, 1990b). The lipase of M. freudenreichii was strongly inhibited by organophosphates and divalent metal ions, but less so by EDTA or pCMB (Lawrence et al., 1967). 

Of the three primary events in cheese ripening, i.e., glycolysis, lipolysis, and proteolysis, proteolysis is usually the rate-limiting one. Glycolysis is normally very rapid and is complete in most varieties within 24 hr therefore, acceleration of glycolysis is not of interest. The modification and catabolism of lactate is either of little or no consequence (e.g., Cheddar or Dutch varieties) or is quite rapid—2-3 weeks (e.g., Swiss types, Camembert)—and consequently its acceleration is not important. Lipolysis is limited in most cheese varieties, exceptions being some Italian varieties, e.g., Romano and... 

The mode and extent of milk fat degradation de- 10.28. Lipolysis during ripening of blue cheese 1... 

In the dairy industry, lipases are used in the hydrolysis of milk fat. Applications include flavor enhancement of cheeses, acceleration of cheese ripening, manufacture of cheeselike products, and lipolysis of butterfat and cream. Sources of lipases for cheese enhancement are the pancreatic glands or pregastric tissues of lamb, calf, or kid. Each pregastric lipase leads to its own characteristic flavor pattern, and these enzymes are essential in the production of quality cheeses such as Romano and provolone [15]. Pregastric lipases have also been used for the treatment of calf diarrhea or scours [15] and have potential for the treatment of malabsorption syndrome in children. 

Godinho, M. and Fox, P. F. (1981). Ripening of Blue cheese Influence of salting rate on lipolysis and carbonyl formation. Milckwissenschaft 36,476-478. 

The role of milk-fat in the development of flavor in cheese during ripening will be discussed below although it should not be forgotten that lipolysis and the metabolism of fatty acids do not occur in isolation from other important biochemical events during ripening. 

Figure 11.8. Pathways for the catabolism of free fatty acids in cheese during ripening (reprinted from Cheese Chemistry, Physics and Microbiology, 3rd edn P.F. Fox et al. (eds.), Collins, Y.F., McSweeney, P.L.H., Wilkinson, M.G., Lipolysis and Catabolism of fatty acids in cheese, pp. 373-379, 2004, with permission from Elsevier).

Lipolysis plays an important role in providing the characteristic flavor of many milk products. In particular, the ripening of most cheese varieties is accompanied by lipolysis due to microorganisms or to added enzyme preparations, and, in raw milk cheese, to the milk LPL. Lipolysis is not extensive, but is more pronounced in some cheeses (e.g., blue-veined and hard Italian varieties), than in others. Excessive lipolysis renders the cheese unacceptable (Fox and Law, 1991 Gripon et al., 1991). 

Quantification of FFAs in dairy products, especially in cheese, is particularly important due to the impact of some FFAs on flavor. However, FFAs act as precursors of a wide range of flavor compounds (e.g., methyl ketones, lactones, esters and aldehydes), (Singh et al, 2003). The extent of lipolysis in cheese varies widely between varieties (Table 19.2). Typically, those cheeses with more than 3000 mg/kg have a characteristic lipolytic aroma/flavor and lipolysis plays an important role in their ripening. A major difficulty in quantifying FFAs in cheese is the distribution of FFAs of different chain length within the cheese matrix. SCFFA (C4 o—C8 0) partition mainly into the aqueous phase, whereas medium (Cio q—C14 0) and longer... 

Contarini, G., Toppino, P.M. 1995. Lipolysis in Gorgonzola cheese during ripening. Int. Dairy J. 5, 141-155. 

Freitas, A.C., Malcata, F.X. 1998. Lipolysis in Picante cheese Influence of milk type and ripening time on free fatty acid profile. Lait 78, 251-258. 

An extension of this technology lead to the development of enzyme modified cheeses or EMC which are a very important product. The basic function of the process was to shorten the ripening time of a mature cheese without losing flavor. The potential financial gains are obvious. Young cheeses are subjected to a controlled lipolysis and proteolysis which is brought about by adding suitable microbial enzymes (8). After thermal inactivation of the enzymes, a pasty product is obtained which can have a flavor intensity of up to 20 times that of the mature cheese. 

Several varieties of the popular Italian cheeses owe their characteristic flavor to the action of lipolytic enzymes. Romano is a very hard, ripened cheese. Originally, it was made from ewe s milk it is now also made from cow s and goat s milk. The sharp, peppery-like flavor, traditionally termed "piquant", results from extensive lipolysis ( 1). Long and Harper (2) and Arnold e t al. (3)... 

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