Casein, enzymatic hydrolysis

Total riboflavin Casein Enzymatic hydrolysis with Precolumn ODS... 

There is currently little understanding of the influence of interfacial composition and (nano)structure on the kinetics of enzymatic hydrolysis of biopolymers and lipids. However, a few preliminary studies are beginning to emerge (McClements et al., 2008 Dickinson, 2008). Thus, for example, Jourdain et al. (2009) have shown recently that, in a mixed5 sodium caseinate + dextran sulfate system, the measured interfacial viscosity increased from qs = 220 mN s m 1 without enzyme to qs = 950 mN s m 1 with trypsin present. At the same time, the interfacial elasticity was initially slightly reduced from (7S = 1.6 mN m 1 to (h = 0.7 mN m, although it later returned to close to its original value. Conversely, in the... 

Any factor that accelerates the crystallization of lactose shortens the storage life of the product. At very low temperatures (below — 23°C), neither lactose crystallization nor casein flocculation occurs, even after long periods. Enzymatic hydrolysis of lactose by /S-galactosidase before freezing retards or prevents lactose crystallization and casein precipitation in proportion to the extent of the hydrolysis (Figure 2.14). 

Enzymatic hydrolysis of food proteins yields peptides that are of great interest to the food industry and are utilized for various purposes, e.g., improving the functional properties of foods, parenteral feeding (casein hydrolyzates), or milk protein substitutes in cases of intolerance. 

Enzymatic hydrolysis modifies the foaming properties of casein. Protamex hydrolysates of sodium caseinate (DH 0.5 and 1.0%) displayed increased foam expansion at pH 2, 8 and 10 as compared with unhydrolyzed caseinate (Slattery and FitzGerald, 1998). Hydrophobic peptides resulting from... 

Mahmoud, M.I., Malone, W.T., and Cordle, C.T. 1992. Enzymatic hydrolysis of casein effect of degree of hydrolysis on antigenicity and physical properties. J. Food Sci. 57, 1223—1229. 

Righetti, P.G., Nembri, F., Bossi, A., and Mortarino, M. 1997. Continuous enzymatic hydrolysis of beta-casein and isoelectric collection of some of the biologically active peptides in an electric field. Biotechnol. Prog. 13, 258—264. 

Application and Principle This procedure is used to determine proteolytic activity, expressed in spectrophotometric acid protease units (SAP), of preparations derived from Aspergillus niger var. and Aspergillus oryzae var. The test is based on a 30-min enzymatic hydrolysis of a Hammarsten Casein Substrate at pH 3.0 and at 37°. Unhydrolyzed substrate is precipitated with trichloroacetic acid and removed by filtration. The quantity of solubilized casein in the filtrate is determined spectrophotometrically. 

Heat and alkaline treatments have been known since the early part of the century to raoemize amino acid residues in proteins (1,2,). Dakin and Dudley (3) also studied digestibility of casein in vitro and in vivo after hydroxide treatment. Heating casein with 0.5 N NaOH at 37° for about 30 days completely prevented enzymatic hydrolysis and intestinal absorption when the treated casein was fed to a dog. The kinetics of base-catalyzed racemization of proteins was investigated by Levene and Bass (4-6). In these early studies, the extent of racemization was measured by changes in optical rotation. 

Many workers have studied the influence of enzymatic hydrolysis on the functional properties of various food proteins, and much of this work has recently been reviewed by Richardson (2). However, there seem to be very few reports which quantitatively relate functionality to parameters which characterize the protein hydrolysates per se (e.g. molecular weight). Ricks et al. (3 ) examined the solubility and taste of a number of pure proteins (denatured pepsin, lactoblobulin, a-Sj -, K-, and 8-casein) hydrolysed with... 

Pahkala, E., Pihlanto—Leppfila, A., Leukkanen, M., and Antila, V. (1989). Decomposition of milk proteins during the ripening of cheese. 1. Enzymatic hydrolysis of Oj-casein. Meijeritiet. Aikak. 47, 39-47. 

The K-casein provides a layer of hydrophilic polymer at the surface of the micelle that contributes to stability. Removal of the K-casein by enzymatic hydrolysis with chymosin (rennin) results in the micelles eventually undergoing coagulation. This is the principle of cheese making. 

Besides being important building blocks in the construction of proteins, some peptides possess their own biological activity. Milk, in particular, is a source of many biologically active peptides. The enzymatic hydrolysis of the milk protein casein releases opioid peptides, which have pharmacological activities such as analgesia and sleep-inducing effects. Other peptides derived from casein are involved in calcium flow in tissues and modification of the immune system response. Other milk peptides... 

Trusek-Holownia (2008) reports the use of a membrane reactor for the enzymatic hydrolysis of casein. Although such processes may never be performed at a large enough scale to justily intensification of the process there is another driver, which is to minimise usage of the enzymes themselves as they are very expensive. In this... 

Freimuth, U., Krause, W. and Doss, A. (1978). On the alkali treatment of proteins. II. Enzymatic hydrolysis of alkali-treated p-casein and acid casein. Nahrung, 22, 557-568. (German). 

---