Amino acids cheese

In traditional cooking of proteinaceous foods, the fundamental difference between Western and Oriental cultures is that the former cooks proteins with unseasoned fats and the latter cooks with many kinds of traditional seasonings that have tastes of amino acids. Western cultures have some traditional foods with amino acid taste such as cheese. Protein hydrolysates are popular as seasonings (225). 

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. 

Tyramine is an amino acid which is present in large quantities in protein rich, fermented and stored products like some cheeses, sausages, red wines, beers etcetera. Tyramine is metabolized into nor-adrenaline by the enzyme mono-amino-oxidase (MAO). If MAO is inhibited by drags nor-adrenaline is accumulated and can give hypertensive crises. 

Ripened cheeses contain higher average concentrations of amines than do unripened cheeses, a difference that could be related to processing (Martelli et ah, 1993 Schneller et al., 1997). Casein proteolysis that occurs during cheese manufacture may result in an increased level of free amino acids. These amino acids are then decarboxylated, resulting in the formation of biogenic amines. A... 

Novella-Rodriguez et al. (2002) tested in vitro the starter bacteria Lactococcus lactis subspecies lactis combined with Lactococcus lactis subspecies cremoris, and Lactococcus lactis subspecies lactis, and found that they did not decarboxylate amino acids or produce amines. The conclusion was that the biogenic amine content found in cheese should be attributed to the presence of non-starter bacteria. Some researchers believe that biogenic amines are produced through the interaction of adventitious microorganisms (Joosten and... 

Fourth, the salt concentration in cheese also influences the production of biogenic amines (Kebary et al., 1999 Joosten, 1988). Gouda cheese contains 3.5 mmol histamine per kg with a salt water ratio of 0.048, and 2.1 mmol histamine with a salt water ratio of 0.026 (Joosten, 1988). Each cheese has its own characteristic free amino acid and biogenic amine profiles, resulting from its specific degradation, interconversion, and synthesis (Polo et al., 1985). 

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. 

Martelli, A., Arlorio, M. and Tourn, M.L. (1993). Determination of amines and precursor amino acids in gorgonzola cheese by ion pair HPLC without derivation, Li Rivista di Scienza delValimentazione, 3, 261. 

Pinho, O., Ferreira, I.M.P.L., Mendes, E., Oliveira, B.M. and Ferreira, M. (2001). Effect of temperature on evolution of free amino acid and biogenic amine contents during storage of Azeitao cheese. Food Chem., 75, 287. 

Polo, M.C., Ramos, M. and Sanchez, R. (1985). Free amino acids by high performance liquid chromatography and peptides by gel electrophoresis in Mahon cheese during ripening. Food Chem., 16, 85. 

Second, the essential amino acids leucine, isoleucine, and phenylalanine are precursors for several additional tomato flavor elements. Here, too, these flavor elements are important flavor constituents in other fruits, including strawberries and apples. They are also found in breads, cheeses, wine, and beer. 

Specificity. The generally claimed specific action of enzymes is not as sharply defined as is often expected. Proteases are broad in the range of amino acid bonds they hydrolyze and exhibit only a degree of specificity. Careful investigation of the range of bonds attacked, and testing for comparable action on the actual protein target, will enable an enzyme to be chosen that has suitable performance. Some proteases are extremely narrow in their action, for example the various cheese rennets. 

Different authors used RP-HPLC and UV detection to monitor peptide formation during cheese ripening [174-178], providing valuable information about proteolysis. When large hydrophobic peptide need to be separated an lEC represents the best choice [179]. Nevertheless, the identification of these peptides is essential for the complete understanding of the proteolytic process. The peptides eluted from the LC column can be subjected to ESl-MS for molecular weight determination and MS/MS for amino acid sequence determination, which allow rapid peptide identification [172]. HPLC-ESl-MS and MS/MS techniques have been successfully used for peptide mass fingerprint purposes for sequence analysis of purified albumin from Theobroma cacao seeds [180,181]. 

Owing to very low thresholds, volatile sulfur compounds (VSCs) usually have prime impact on food aromas they are found in lots of natural sources, including fermented foods (e.g. wine, beer, cheese), and act as both flavours and off-flavours [249, 250]. Although their biogenetic formation has been elucidated in detail, only few biotechnological processes with potential for commercial application have been reported. The sulfur-containing amino acids L-methionine and L-cysteine are the natural precursors of a wide variety of VSCs. Methanethiol is the most frequently found VSC in cheese and can be readily oxidised to other VSCs, such as dimethyl suMde and dimethyl disulfide, or... 

The level of proteolysis in cheese varies from limited (e.g. Mozzarella) through moderate (e.g. Cheddar and Gouda) to very extensive (e.g. Blue cheeses). The products of proteolysis range from very large polypeptides, only a little smaller than the parent caseins, to amino acids which may, in turn, be catabolized to a very diverse range of sapid compounds, including amines, acids and sulphur compounds. 

Figure 10.24 Concentration of individual amino acids in 60-day-old Cheddar cheese, made with a single-strain starter Lactococcus lactis ssp. cremoris AM2, G11/C25 or HP (from...

The taste of cheese is concentrated in the water-soluble fraction (peptides, amino acids, organic acids, amines, NaCl) while the aroma is mainly in the volatile fraction. Initially, it was believed that cheese flavour was due to one... 

In defining the nutritional equivalence of dairy foods, FDA considered only 11 to 15 nutrients for milk substitutes, 1 nutrient for cream substitutes, and 4 to 9 nutrients for cheese substitutes (FDA 1978). Yet, data from the Consumer and Food Economics Institute, USDA (1976), reveal that traditional milk, cream, and cheese contain an array of nutrients including protein, fat, carbohydrate, and at least 15 minerals and vitamins and 18 amino acids. Thus, under FDA s proposal (FDA 1978), which has been withdrawn (FDA 1983) but, as mentioned above, may in effect be applied, a substitute dairy product could be declared nutritionally equivalent to its traditional counterpart and yet (1) not contain all of the nutrients in the traditional food, or (2) contain some or all of these other nutrients but in lesser quantities, or (3) contain some of the nutrients such as sodium in excessive amounts, or (4) contain more or less energy (NDC 1983C). 

The gross proteolysis of casein is probably due solely to rennet and plasmin activity (O Keeffe et al. 1978). Bacterial proteases and peptides are responsible for subsequent breakdown of the large peptides produced by rennet and plasmin into successively smaller peptides and finally amino acids (O Keeffe et al. 1978). If the relative rate of proteinase activity by rennet, plasmin, and bacterial proteases exceeds that of the bacterial peptidase system, bitterness in the cheese could result. Bitter peptides can be produced from a,-,- or /3-casein by the action of rennet or the activity of bacterial proteinase on /3-casein (Visser et al. 1983). The proteolytic breakdown of /3-casein and the subsequent development of bitterness are strongly retarded by the presence of salt (Fox and Walley 1971 Stadhouders et al. 1983). The principal source of bitter peptides in Gouda cheese is 3-casein, and more particularly the C-terminal region, i.e., 3(193-209) and 3(193-207) (Visser et al. 1983). In model systems, bitter peptides are completely debittered by a peptidases system of S. cremoris (Visser et al. 1983). 

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