The Functionality of Inulin as a Sugar Replacer in Cakes and Biscuits; Highlighting the Influence of Differences in Degree of Polymerisation on the Properties of Cake Batter and Product

Sugar has multiple roles in baked products; competing for water and as such reducing starch gelatinisation and gluten development, behaving as a fluid during cooking, recrystallising on cooling; roles which influence properties such as aeration, texture and mouthfeel. Partial replacement with inulin, can provide beneficial nutritional and functional properties. This paper investigated the degree of polymerisation (DP) of two commercial inulins and their influence on baked product properties as a 30% sugar replacer. The two inulins varied substantially in their proportion of longer fructans (32.7% compared to 17.5% of DP > 11). The lower DP inulin led to a cake batter with very similar viscoelastic properties to the standard sugar batter, and subsequently to a very similar baked cake crumb structure, cake texture and mouthfeel. The higher DP inulin led to a more viscous batter, and cake with a less homogenous crumb structure that was perceived to be dryer and more mouthcoating. The subsequent use of the lower DP inulin in a biscuit formulation resulted in a slightly less elastic dough and consequently a softer and less crunchy biscuit. In summary, the success of inulin in providing functional properties that can enable sugar reduction in baked products is dependent on the degree of polymerisation of the inulin and rheological parameters needed in the specific bakery matrix.