|Liu, Yan - China Agriculture University|
|Selig, Michael - Cornell University - New York|
|Yin, Lijun - China Agriculture University|
|Abbaspourrad, Alireza - Cornell University - New York|
Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2018
Publication Date: 2/1/2018
Publication URL: http://handle.nal.usda.gov/10113/5907463
Citation: Liu, Y., Selig, M.J., Yadav, M.P., Yin, L., Abbaspourrad, A. 2018. Transglutaminase-treated conjugation of sodium caseinate and corn fiber gum hydrolysate: Interfacial and dilatational properties. Carbohydrate Polymers. 187:26-34.
Interpretive Summary: Corn bran/fiber is an abundant low value material used for animal feed. Usually it is obtained from corn dry or wet milling industries. Previously we reported that corn fiber gum (CFG) which is deficient in protein, has inferior flavor stabilizer in comparison to protein rich CFG. One way to improve the properties of CFG would be to link a commercial protein to CFG to improve its flavor stabilizing capacity. In this study, we have treated CFG polymer with acid to break it down into smaller molecules and we linked them with protein (casein) by using an enzyme (transglutaminase). This new conjugate of small CFG molecules and protein is more efficient to make a stable emulsion than the high molecular weight CFG. To prove the high efficiency of this conjugate, several properties of its emulsions were studied. The study has demonstrated that crosslinking of the CFG fragments and sodium caseinate was more favorable at high protein to carbohydrate weight ratios. After crosslinking, the adsorbed CFG-caseinate interfacial layer became more stable and viscoelastic as compared to only the caseinate layer. These findings will benefit U. S. corn processors by adding value and creating an additional market for their by-products. It will also benefit U. S. manufacturers of CFG who will be able to produce an improved corn fiber gum emulsifier by linking protein to it. The generation and recovery of additional valuable product from corn milling by-products will also indirectly help to reduce overall cost of fuel ethanol produced from corn kernels.
Technical Abstract: The effects of thermochemical hydrolysis of corn fiber gum (CFG) and conjugation of the resulting oligomers with sodium caseinate in presence of transglutaminase was studied. The dynamic interfacial tension at the oil-water interface was studied and the molecular characteristics were determined by high performance size exclusion chromatography. It was found that a shorter incubation time is needed to form a conjugate between the hydrolyzed CFG and sodium caseinate in the presence of transglutaminase at a high sodium caseinate to CFG weight ratio (2:1). The study of the interfacial properties as a function of the weight ratio of CFG and sodium caseinate using a pendant drop tensiometer showed an increase in rearrangement rate of CFG and its hydrolysate at the oil-water interface after crosslinking with caseinate, especially at higher caseinate to CFG or CFG hydrolysate weight ratio. Dilatational interfacial study results showed that the elastic moduli of CFG-caseinate conjugate or CFG hydrolysate-caseinate conjugate did not change significantly in comparison to their mixtures indicating that the sodium caseinate formed a covalent bond with a single CFG molecule instead of two or more molecules during crosslinking reaction.