Effects of caseinate deamidation on transglutaminase-induced glucosamine conjugation and cross-linking as well as properties of the treated caseinates

Pre‐deamidation of soy protein isolate exerts impacts on transglutaminase‐induced glucosamine glycation and cross‐linking as well as properties of the products

“…degree of deamidation of the products). This had been observed in the past three studies using casein, soy and sunflower proteins as target substrates, which provided support to the present study. DSPI1 was generated with a reaction time of 4 h and, therefore, had lower degree of deamidation than DSPI2 with a reaction time of 10 h. Based on the speciality of TGase, glutamine residues in the proteins are the sites where TGase‐induced cross‐linking and glucosamine conjugation occur.…”

“…That is, both GC‐DSPI1 and GC‐DSPI2 would possess more reactable NH 2 than GC‐SPI. Similar results was found in a previous study using casein as the targeted protein for the HCl‐induced deamidation followed by the TGase‐induced glycation and cross‐linking . It is thus verified that SPI deamidation is applicable to control (or decrease) TGase‐induced glycation and cross‐linking.…”

“…It is thus verified that SPI deamidation is applicable to control (or decrease) TGase‐induced glycation and cross‐linking. The present study also utilised SDS‐PAGE assaying to confirm the TGase‐induced protein glycation and cross‐linking of GC‐SPI, GC‐DSPI1 and GC‐DSPI2, as did three previous studies . Protein staining results showed that they three all were cross‐linked protein products, while saccharide staining results clarify that all of them were glycated protein products.…”

“…A C 18 column (4.6 mm × 250 mm i.d., 5 µm; Elite Technologies, Dalian, China) was used for the chromatography separation. The procedure and conditions used were the same to those described in a previous study . Glucosamine conjugated into protein substrates of 1 kg was calculated by the regression equation generated from standard glucosamine solutions.…”

“…Consequentially, the two reactions induced by TGase are kept in less reaction extent, and the properties of the glycated and cross‐linked products would be influenced by the pre‐deamidation. In a previous study, casein deamidation by HCl was shown to have impacts on the two reactions and properties of the products . Whether HCl deamidation of soy protein is also applicable to control the two reactions, and how the properties of the obtained product are impacted, still remain unknown issues so far, and should be clarified.…”