The preparation and properties of three caseinate-hydrolyzed bovine gelatin composites generated by microbial transglutaminase

摘要

Caseinate was mixed with trypsin-hydrolyzed bovine gelatin of degree of hydrolysis of 2% in three ratios of 2:1, 4:1 and 6:1 (w/w) and fixed protein concentration of 50 g/L, and treated by transglutaminase of 10 U/g protein at 45???°C for 4 h. Three composites generated were protein polymers containing 4-hydroxyproline of 14.50, 10.30 and 6.55 g/kg protein, respectively, and showed better solubility in pH 4.5 but some lower or similar solubility in pH 7?￠????8, higher surface hydrophobicity (1480.1 vs. 1636.1?￠????2143.8) and water holding capacity (WHC) (3.17 vs. 5.96?￠????17.30 kg water/kg protein), but lower in vitro digestibility than caseinate. More hydrolyzed gelatin used in composite preparation conferred the composite enhanced solubility but decreased in vitro digestibility and WHC. The composite generated from caseinate and hydrolyzed gelatin in a ratio of 6:1 (w/w) had the best WHC and might be a potential ingredient for the processed foods such as ham and fish ball.