| Abstract
| - Sodium caseinate (NaCN), hydrolyzed with Protamex, a Bacillus proteinase preparation, to 0.5, 1.3,and 17.5% degrees of hydrolysis, was incubated with transglutaminase (TGase) for 3, 42, and 290min at enzyme/substrate ratios of 1, 1, and 10% (w/w), respectively, pre- and post-hydrolysis. Theelectrophoretic, reversed-phase high-performance liquid chromatography (RP-HPLC) and nitrogensolubility profiles of the modified products were investigated. Combinations of hydrolysis and incubationwith TGase generated products displaying novel physicochemical and nitrogen solubility properties.Significant changes in sodium dodecyl sulfate (SDS) and urea polyacrylamide gel electrophoresisprofiles were apparent in the modified caseinate samples. Extensive TGase cross-linking resulted inpolymers that were unable to enter the resolving gel during SDS polyacrylamide gradient gelelectrophoresis. Extensive combined enzymatic modification resulted in peptides eluting earlier onRP-HPLC than limited combined enzymatic modification or limited hydrolysis. Combination ofenzymatic treatments resulted in significantly (P< 0.005) improved solubility around pH 4.6, comparedto incubation with TGase or hydrolysis of NaCN alone. Keywords: Transglutaminase; casein hydrolysates; nitrogen solubility index
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