Effect of deamidation by protein-glutaminase on physicochemical and functional properties of skim milk

Modifications of structures and functions of caseins: a scientific and technological challenge

“…All these observations suggested that deamidation induced dissociation of casein micelles due to increase in the electrostatic repulsions between caseins and breaking of salt bridges. The particle size analysis and observations by transmission electron microscopy confirmed this destructuration of casein micelles by showing small particles in highly deamidated skim milk (Miwa et al 2010).…”

“…This enzyme was discovered in the culture supernatant of Chryseobacterium proteolyticum (Yamaguchi and Yokoe 2000;Yamaguchi et al 2001), and its action was investigated on several food proteins Gu et al 2001;De Jong and Koppelman 2002;Yong et al 2004Yong et al , 2006. On skim milk proteins, Miwa et al (2010) showed that deamidation increased the electronegativity of caseins due to the formation of supplementary carboxyl groups leading to a reduction of the pHi toward lower pH. Turbidity decreased until the milk became translucent.…”

“…The solubility, viscosity, and emulsifying capacity of milk were improved with an increase of the deamidation degree (Miwa et al 2010). Recently, Miwa et al (2014) studied the effect of milk enzymatic deamidation on the textural and microstructural properties of yoghurts, and they highlighted a decrease in their firmness.…”

The extraction of gelatine from mackerel (Scomber scombrus) heads with the use of different organic acids

“…However, the conversion of protein amide groups to carboxyl groups during the deamidation of asparagine and glutamine amide residues affects both the charge and the hydrophobicity of gelatine by introducing negatively charged carboxyl groups (Lindner and Helliger, 2001). This leads to a decrease in the isoelectric point (Miwa et al, 2010). It was reported that the gelatine type A or acid-processed gelatine has an isoelectric point that can vary from 6.5 to 9.0 whereas gelatine type B or alkaline-processed gelatines has an isoelectric points found over a narrower pH range, typically 4.…”

Enzymatic modification of dairy product texture

“…Treatment of skim milk with PG leads to a reduction in turbidity and an increase in viscosity, with electron microscopy indicating the dissociation of casein micelles into considerably smaller particles, as also measured by particle size analysis (Miwa et al, 2010). Levels of nonsedimentable casein and calcium increase as a result of the PGinduced disruption of casein micelles, but levels of nonpermeable (5 kDa) calcium remained constant, indicating that calcium phosphate nanoclusters and calcium caseinate interactions are not disrupted by treatment with PG (Miwa et al, 2010).…”