Differential Scanning Calorimetry of Edible Plant-Based Protein Using Glycerol as a Medium

Plant-based protein isolates are common food ingredients. Differential scanning calorimetry of isolates is used to predict their functional properties, as well as to evaluate the propensity of these isolates to form bioplastics through the heat-induced formation of intermolecular disulfide, hydrophobic, and other types of bonds. In this study, we use differential scanning calorimetry of a suspension containing a soy protein isolate (SPI) in glycerol. It is shown that heat is released upon heating the isolate in the presence of glycerol. The preliminary thermal denaturation of a water solution of soy proteins (95°C, 30 min) increases the thermal effect, while the enzymatic hydrolysis of the protein leads to a loss of the exothermic thermal effect. The addition of β-mercaptoethanol to the SPI has no effect on the observed exothermic process, which indicates the absence of a contribution of the formation of new disulfide bonds in this case. Thus, the formation of bioplastic by an SPI does not depend on the formation of new disulfide bonds, and the use of the differential scanning calorimetry method can be considered as a method for estimating the solubility of the protein preparation.