Characterisation of the physicochemical, residual antigenicity and cell activity properties of transglutaminase cross-linked sodium caseinate hydrolysates

Sodium caseinate (NaCN) was hydrolysed with Prolyve 1000, a Bacillus licheniformis derived proteolytic preparation to a degree of hydrolysis of 21.57 ± 1.2%. An aliquot of this hydrolysate was cross-linked with transglutaminase (TGase). Furthermore, TGase cross-linked NaCN was also hydrolysed with Prolyve 1000. These three hydrolysate samples had broadly similar peptide and molecular mass distribution profiles while the reduction in residual antigenicity was not statistically significant (P > 0.05) between the hydrolysates. Jurkat T cell viability studies showed that the hydrolysate cross-linked prior to hydrolysis was the most cytotoxic of the three hydrolysates studied. There was no significant difference (P > 0.05) between the hydrolysates in catalase activity and glutathione content in Jurkat T cells following 24 h incubation. However, the production of interleukin-2 and interleukin-10 in Con-A stimulated Jurkat T cells was significantly decreased (P < 0.05) in cells incubated with the NaCN hydrolysate that was cross-linked prior to hydrolysis.