No abstract

D-Allulose (a monosaccharide and C3 epimer of fructose), one of the common rare sugars is getting attention due to its low caloric values. In this study, D-Allulose was used as a replacement of sucrose at different ratios (D-Allulose/ Sucrose: 35/0, 20/15, 10/25, 0/35) to formulate pectin-based soft confectionery gels. Soy protein isolate was also added to increase the protein content. Physical properties, such as hardness, moisture content, pH, and color, were measured for the gels. Higher hardness values were obtained for the soy protein containing gels due to pectin-soy protein interaction (p < 0.05). Also, higher moisture content was observed in soy protein containing gels (p < 0.05). In addition, nuclear magnetic resonance T 2 relaxation times were measured at low field ($0.5 T) to determine how the water distribution in the samples changed and to observe how D-Allulose affected the polymer-water interactions. The study also showed that the presence of D-Allulose increased the crystallization tendency (% crystallinity of 7.9) of the pectin gels. X-ray diffraction results showed the D-allulose peaks at 33.76 and 48.68 o θ. Morphologies of the gels were also examined by scanning electron microscope. Sugar type and soy protein isolate addition were found to have significant impact on the gel formulations.

Confectionery gels are known to be high-caloric products due their high sugar content. Changing their formulations by substituting the sugar with alternative natural sweeteners and functionalising them, the addition of proteins has gained attention. Understanding the rate of digestion of these products is also important for selecting the appropriate formulation. In this study, in vitro gastric digestion behaviour of the gels formulated with D-allulose, a low-calorie rare sugar, soy protein isolate (SPI) (1%, 2.5%) and pectin (4%) were examined. Digestion decreased the hardness of the gels (P < 0.05), but, at 2.5% SPI concentration. Moisture content of the samples increased after digestion and presence of SPI induced higher water uptake. At the end of 2 h of digestion, 1% soy protein isolate containing gels had the highest brix values showing that after a certain concentration, soy protein isolate governed the system due to improved soy protein-pectin interaction or due to improved gelation with Maillard reaction. NMR relaxometry experiments further confirmed the changes in the gels with the increase in T 2 values. Power law model was fitted for the dissolution behaviour using the o Brix values of the digestion medium. Dissolution of sugar and the contribution of SPI to the gel network were clearly observed in SEM images. Results showed that these gels had the potential to slow down the emptying rate of stomach thus could lead to 'fullness' for a longer time.