The effect of transglutaminase from Streptomyces sp. CBMAI 837 on the gelation of acidified sodium caseinate

The influence of the transglutaminase (TG) from a newly isolated Brazilian Streptomyces sp. CBMAI 837 and sodium caseinate concentration (4% and 8%, w/w) on acid-gel properties was studied. Standard gels with and without commercial transglutaminase samples were tested in parallel. The mechanical properties of the samples (stress and strain at rupture and elasticity modulus) were evaluated using uniaxial compression measurements. Texture parameters showed that the commercial TG gels had greater values of elasticity modulus, while addition of the Streptomyces sp. CBMAI 837 TG to the gel led to the formation of less elastic, but more deformable gels. The electrophoresis results showed that the commercial TG enzyme in this system promoted higher molecular mass protein polymers than the enzyme from Streptomyces sp. CBMAI 837. Microscopy and water-holding capacity (WHC) observations showed that all the gel characteristics could be associated with specific interactions promoted by each TG tested.