Despite of the fact that the use of sweeteners as sugar substitute in food products is effective in reduction of calories and related diseases, they are typically associated with change in the texture and sensory properties of the product. In the present study, the effect of partial and overall replacement of sucrose with agave nectar and stevia on chemical, physical, rheological, and sensory properties of dark chocolate was evaluated. The results indicated that the amount of water, water activity, fat, and protein of chocolate dropped with an increase in the amount of agave nectar and a decrease in stevia. There was no significant difference between fat and protein of the control sample and the one containing agave nectar while there was a significant difference between other samples. The hardness of the control sample was more than that of other ones, and replacing sugar with agave nectar and stevia led to a decrease in the chocolate hardness. L*, hue, and Chroma mean of the sample with stevia was higher and that of the sample with agave nectar was lower than all other samples, which indicated the favorable quality of the sample prepared with agave nectar. Fitting the experimental data with different model indicated that Windhab Model was the best model to predict the rheological properties of dark chocolate. In Windhab Model, with an increase in the amount of agave and sucrose, linear yield stress and shear stress increased in chocolate, and the control sample experienced a higher level of yield stress. Moreover, the apparent viscosity of the control sample was more than other ones, and replacing sucrose with agave nectar and especially with stevia led to a drop in apparent viscosity. Regarding the sensory properties, the sample containing agave nectar obtained a higher score than the control sample, and the quality of the produced chocolate using agave nectar was evaluated to be the best one. The results of the present study indicated that using a combination of sucrose, agave nectar and stevia and agave nectar alone is an appropriate solution for producing chocolate, and this product can fulfill the needs of individuals with diabetes mellitus, cardiovascular diseases, and Gastrointestinal cancer.
