Functionality of inulin and polydextrose as sucrose replacers in sugar-free dark chocolate manufacture - effect of fat content and bulk mixture concentration on rheological, mechanical and melting properties

Inulin and polydextrose are key bulk sugar replacers and have been utilised extensively as functional ingredients due to their fibre and prebiotic claims. This study investigated effects of fat content and bulk mixture concentrations of inulin and polydextrose on rheological properties, mechanical and melting characteristics of sugar-free dark chocolates sweetened with steviol glycosides. Sucrose was replaced with polydextrose and inulin (0: 100, 25: 75, 50: 50, 75: 25, 100: 0) at different fat contents (27%, 30% and 33%). Reducing fat content from 33% to 27% had similar effects on the sugar-free dark chocolates as it did on reference chocolate. Increasing inulin concentrations with simultaneous reduction in polydextrose resulted in consistent increases in Casson plastic viscosity and decreases in Casson yield stress regardless of the fat content. These were explained by microstructural examination of the sugar replacers, which revealed wide variations in network structure. Understanding these factors would help reduce energy load from fat in sugar-free chocolate confectionery.