Cheese acid development

Kebary, K.M.K., El-Sonbaty, A.H. and Badawi, R.M. (1999). Effects of heating milk and accelerating ripening of low fat Ras cheese on biogenic amines and free amino acids development, Food Chem., 64, 67. 

The manufacturing process for Swiss cheese was developed in Emmen-thal, Switzerland, hence the name Emmentaler cheese (known as Swiss cheese in the United States). It is hard, pressed-curd cheese with an elastic body and a mild, nut-like, sweetish flavor. Swiss cheese is best known for the large holes or eyes that develop in the curd as the cheese ripens. S. thermophilus andL. bulgaricus or Lactobacillus helveticus are used for acid production, which aids in expelling whey from the curd, whereas Propionibacterium shermanii is largely responsible for the characteristic sweet flavor and eye formation. 

Bactofugation, a process based on centrifugal separation of bacteria and their spores, is practiced in the Netherlands. Since the spores of lactate-fermenting Clostridia (butyric acid bacteria) are removed, there is less risk that Gouda cheese will develop the late blowing defect caused by the metabolism of these bacteria (Van den Berg et al 1980). 

Pasteurization inactivates many enzymes, including alkaline phosphatase and lipoprotein lipase. The absence of active alkaline phosphatase in cheese is often used to determine if the milk has been properly pasteurized prior to cheesemaking. Since pasteurization kills most of the lactic acid bacteria in milk, the lactic acid developed during cheese-... 

The starter culture used in cheesemaking depends on the type of cheese and the temperature to which the curd is heated. Streptococcus lactis or S. cremoris are used in cheese varieties heated to 40°C or less, since no acid development occurs with these cultures above that temperature (Sellars and Babel 1970). High-temperature homolactic bacteria such as S. thermophilus, Lactobacillus bulgaricus, or L. helveticus are used in the manufacture of cheese varieties heated to higher temperatures. 

Excessive or insufficient acid development during manufacture can produce variability in the moisture content of cheese and defects in flavor, body, texture, color, and finish (Van Slyke and Price 1952). The rate of lactose fermentation varies with the type of cheese, but the conversion to lactic acid is virtually complete during the first weeks of aging (Van Slyke and Price 1952 Turner and Thomas 1980). Very small amounts of lactose and galactose may be found in cheese months after manufacture. (Huffman and Kristoffersen 1984 Turner and Thomas 1980 Harvey et al. 1981 Thomas and Pearce 1981). Turner and Thomas (1980) showed that the fermentation of residual lactose in Cheddar cheese is affected by the storage temperature, the salt level in the cheese and the salt tolerance of the starter used. 

Free amino acids are further catabolized into several volatile flavor compounds. However, the pathways involved are not fully known. A detailed summary of the various studies on the role of the catabolism of amino acids in cheese flavor development was published by Curtin and McSweeney (2004). Two major pathways have been suggested (1) aminotransferase or lyase activity and (2) deamination or decarboxylation. Aminotransferase activity results in the formation of a-ketoacids and glutamic acid. The a-ketoacids are further degraded to flavor compounds such as hydroxy acids, aldehydes, and carboxylic acids. a-Ketoacids from methionine, branched-chain amino acids (leucine, isoleucine, and valine), or aromatic amino acids (phenylalanine, tyrosine, and tryptophan) serve as the precursors to volatile flavor compounds (Yvon and Rijnen, 2001). Volatile sulfur compounds are primarily formed from methionine. Methanethiol, which at low concentrations, contributes to the characteristic flavor of Cheddar cheese, is formed from the catabolism of methionine (Curtin and McSweeney, 2004 Weimer et al., 1999). Furthermore, bacterial lyases also metabolize methionine to a-ketobutyrate, methanethiol, and ammonia (Tanaka et al., 1985). On catabolism by aminotransferase, aromatic amino acids yield volatile flavor compounds such as benzalde-hyde, phenylacetate, phenylethanol, phenyllactate, etc. Deamination reactions also result in a-ketoacids and ammonia, which add to the flavor of... 

Smit, G., Verheul, A., van Kranenburg, R., Ayad, E., Siezen, R., and Engels, W. 2000. Cheese flavor development by enzymatic conversions of peptides and amino acids. Food Res. Int. 33, 153-160. 

Cheese/hutter flavor. Pregastric lipases, have, been used for years to intensify flavor in Menzyme-modified cheese , and for an intensified butter flavor in lipolyzed butter. Generally the fatty acid residues that need to be split off (to generate the right flavor) are the short chain fatty acids, especially the C to C-jq acids typical of Italian cheeses. The butyric acids are produced from butterfat more specifically by newly developed lipases (really esterases) from Mucor meihei and a very new one, from Aspergillus oryzae, especially for cheddar cheese flavor development. The latter enzyme is marketed under the name Flavor Age (4). Flavors produced in this manner are used widely in cheese-flavored snack foods the value of the intensified cheese flavors is on the order of 50 million, but the. value of the enzymes employed is only about 2-3 million. 

A crude enzyme mixture was isolated from the fermentate of Candida rugosa (ATCC No. 14,830), which is reported to produce high activity lipases ( ). The enzyme mixture was added to a 20% butterfat emulsion. A cheese-like flavor developed after 3 hours of incubation at 37°C. A desirable Romano cheese note developed after continued incubation at room temperature for three days. Nelson (6) studied lipolyzed butterfat flavor and concluded that the surface active characteristics of both fatty acids and mono- and diglycerides were important in the lipolyzed system. A tempering period of hours or even days was usually required to establish equilibrium at the interface of aqueous and fat phases. He pointed out that the lipolyzed flavor appeared to intensify as the equilibration proceeded and that this intensification was sometimes mistaken for residual lipolytic activity. 

Acid production affects almost all facets of cheese manufacture and is probably the most important factor affecting cheese quality. Among the most important consequences of acid development are ... 

Traditionally fermented dairy products have been used as beverages, meal components, and ingredients for many new products [60], The formation of flavor in fermented dairy products is a result of reactions of milk components lactose, fat, and casein. Particularly, the enzymatic degradation of proteins leads to the formation of key-flavor components that contribute to the sensory perception of the products [55], Methyl ketones are responsible for the fruity, musty, and blue cheese flavors of cheese and other dairy products. Aromatic amino acids, branched-chain amino acids, and methionine are the most relevant substrates for cheese flavor development [55]. Volatile sulfur compounds derived from methionine, such as methanethiol, dimethylsulflde, and dimethyltrisul-fide, are regarded as essential components in many cheese varieties [61], Conversion of tryptophan or phenylalanine can also lead to benzaldehyde formation. This compound, which is found in various hard- and soft-type cheeses, contributes positively to the overall flavor [57,62]. The conversion of caseins is undoubtedly the most important biochemical pathway for flavor formation in several cheese types [62,63]. A good balance between proteolysis and peptidolysis prevents the formation of bitterness in cheese [64,65],... 

Steele, J., Broadbent, J., and Kol( J. (2013) Perspectives on the contribution of lactic acid bacteria to cheese flavor development. Curr. Opin. BiotedinoL, 24, 135-141. 

Nisin is a bacteriocin that is produced by some strains of Lactococcus lactis subsp. lactis. Its name is derived from group N (Streptococcus) Inhibitory Substance. It was originally thought (wrongly) that nisin was the cause of slow acid development in cheese manufacture. Interest in nisin was re-stimulated when its effectiveness as an antimicrobial preservative was recognised in the 1940s. 

One frozen dessert is made with Simplesse, a protein-based fat mimetic that contains no fat (37). Other dairy product developments include a fat flavor, produced by encapsulating milk fatty acids in maltodextrins (38) fat-free cottage cheeses and 2% fat milk, prepared by steam stripping cream with partial fat addback, with a cholesterol level about 60% lower than the starting material (39). 

The most abundant milk protein is casein, of which there are several different kinds, usually designated a-, (1-, and K-casein. The different caseins relate to small differences in their amino acid sequences. Casein micelles in milk have diameters less than 300 nm. Disruption of the casein micelles occurs during the preparation of cheese. Lactic acid increases the acidity of the milk until the micelles crosslink and a curd develops. The liquid portion, known as whey, containing water, lactose and some protein, is removed. Addition of the enzyme rennet (chymosin) speeds up the process by hydrolysing a specific peptide bond in K-casein. This opens up the casein and encourages further cross-linking. 

Paprika contains capsombin and capsanthin (Fig. 8.3) which occur mainly as the lauric acid esters, and about 20 other carotenoid pigments. Paprika is produced in many countries which have developed their own specialties. Cayenne or cayenne pepper, produced from a different cultivar of C. annum, is usually more pungent. C. frutescens is the source of the very pungent Tabasco sauce. Paprika oleoresin is produced by solvent extraction of the ground powder. Obviously paprika supplies both flavor and color and its use is limited to those products compatible with the flavor. The recent rise in demand for tomato products in the form of pizza, salsa, etc., has increased the demand for paprika. Paprika is used in meat products, soups, sauces, salad dressings, processed cheese, snacks, confectionery and baked goods.1018... 

Bacteria from the genera Lactobacillus and Streptococcus are involved in the first steps of dairy production (3). The raw materials produced by their effects usually only acquire their final properties after additional fermentation processes. For example, the characteristic taste of Swiss cheese develops during a subsequent propionic acid fermentation. In this process, bacteria from the genus Propionibacterium convert pyruvate to propionate in a complex series of reactions (2). 

For certain foodstuffs, aw may be estimated from chemical compostion. A nomograph relating the aw of freshly made cheese to its content of moisture and NaCi is shown in Figure 7.9. Likewise, various equations relating the aw of cheese to [NaCi], [ash], [12% trichloroacetic acid-soluble N] and pH have been developed (see Marcos, 1993). 

Lipase Triglycerides + HzO -> fatty acids + partial glycerides + glycerol Off flavours in milk flavour development in Blue cheese... 

Woo, A.H. and Lindsay, R.C. (1984) Concentrations of major free fatty acids and flavour development in Italian cheese varieties. J. Dairy Sci., 67, 960-8. 

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