Differential thermal analysis of moisture binding in zephyr with different contents of glucose syrup

When formulating a product, it is just as important to measure changes in free and bound moisture as it is to analyze quality indicators. Zephyr, a Russian whipped dessert, made with sugar dries quickly during storage, gradually losing its moisture. Its crystalline sugar crust thickens and its entire mass saccharifies, resulting in higher firmness and poor appearance. In this study, we aimed to determine the effect of high-conversion glucose syrup on the amount of moisture and its binding forms in zephyr after storage. We studied four samples of pectin-based zephyr with different carbohydrate profiles after three months of storage. Differential scanning calorimetry, thermogravimetry, and non-isothermal kinetics were applied to assess moisture contents and forms of binding in zephyr. Thermograms with thermoanalytical curves were used to analyze the thermolysis of zephyr samples with different contents of glucose syrup in the temperature range from 20 to 300°C. We also studied the endothermic effects at various stages of thermolysis and measured free and bound moisture in the samples. Four stages of their dehydration were identified on the basis of graphical dependences between weight changes and heating temperatures. The control zephyr sample contained more capillary and polymolecular bound moisture, while the experimental samples in which sugar and confectioner’s syrup were partially or completely replaced with high-conversion glucose syrup had more polymolecular and monomolecular bound moisture. The use of high-conversion glucose syrup instead of sugar and confectioner’s syrup reduced the amount of free moisture and therefore increased the amount of bound moisture, keeping zephyr fresh throughout its shelf life.