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Physicochemical and NMR relaxometric characterization of freeze and spray dried glycated soy proteins

Taş, Ozan
Rare sugar is a type of a sugar group consisting of monosaccharides that is not widely found in nature as its name implies. D-psicose that is C-3 epimer of fructose is one of the rare sugars, and its sweetness is equivalent to 70% of the sweetness of sucrose. Researches showed that gylcation with sugars improves their physical and chemical properties. In this study, two different glycation techniques were conducted (freeze drying and spray drying) for soy proteins. In addition to D-Psicose, glycation was performed using glucose and fructose controls. Effect of two different pHs (7,10) and 5 different soy protein : sugar ratios ( 1:1, 2:1, 3:1, 5:1 and 10:1) were tested. For the glycated samples, emulsification activity, hydration behavior by NMR Relaxometery, free amino groups by OPA, protein solubility by Lowry Method, glycation degree, FTIR analysis, reducing sugar and antioxidant activity by DPPH experiments were conducted. According to the results obtained, the best combination to have the highest glycation degree was found to be the samples with pH 7 buffer, 1:1 soy protein to sugar ratio and freeze drying (FD) as the glycation type. This study showed that application of glycation on soy protein improved its functional properties. Indeed, developed properties of D-Psicose helped to improve the functional properties of the soy protein. Also, it was seen that NMR Relaxometry could give insight on the degree of glycation by considering the hydration behavior.