Kinetics of milk coagulation: I. The kinetics of kappa casein hydrolysis in the presence of enzyme deactivation

Abstract

The kinetics of the primary phase of the enzymatic coagulation of milk, i.e., kappa-casein hydrolysis, was investigated in the presence and in the absence of concurrent enzyme deactivation processes. For conditions under which the enzyme is stable, the rate of hydrolysis can be described by Michaelis-Menten kinetics, as has been reported by previous investigators. A mathematical model, experimental data, and parameter estimates are provided for kappa-casein hydrolysis in the presence of concurrent deactivation of enzyme. The model accurately describes the experimental results when porcine pepsin was used as the renneting enzyme. The model and the experimental results indicate that samples of milk treated under conditions where deactivation of enzyme is significant can have fractional conversions of kappa-casein ranging from zero to unity and yet contain no active enzyme at the termination of the treatment.

Lactobacillus rhamnosus GG encapsulation by spray-drying: Milk proteins clotting control to produce innovative matrices

“…19 between destabilized casein micelles leading to gel formation (Carlson et al, 1987). This gel 403 formation is irreversible.…”

Features of the acid protease partition in aqueous two-phase systems of polyethylene glycol–phosphate: Chymosin and pepsin

“…The partition coefficient was defined as: (2) where [P] top and [P] botton are equilibrium concentrations of partitioned protein in the PEG and phosphate rich phases, respectively. In the protein concentration range assayed, a plot of [P] top versus [P] bottom showed a linear behavior, K being its slope.…”

“…This property is used to determine the enzyme activity which is optimal between pH 5.5 and 6.3. At present, other acid proteases with milk clotting activity are used in the cheese industry, such as proteases produced by fungi [2]. We have selected an identical chymosin produced for genetically modified Aspergilus niger because it is one of the acid proteases mostly used in the cheese industry.…”

A study on bovine kappa-casein aggregation after the enzymatic action of chymosin

“…However, the second step can be practically isolated by working with enzyme excess in order to complete the -CN proteolysis as soon as possible at the beginning of the process. Under these conditions, the p--CN aggregation appears as the rate-limiting step of the process [15,38].…”

“…The concept of tensegrity has extreme named para-casein-kappa (p--CN) and a hydrophilic Cterminal moiety called caseinemacropeptide (CMP) [15]. This Cterminal region protrudes to the media, and provides electrostatic and steric stabilization for the protein suspension [16].…”