An investigation into the crystalline structure, and the rheological, thermal, textural and sensory properties of sugar-free milk chocolate: effect of inulin and maltodextrin

Abstract

In this study, sugar was replaced with inulin:maltodextrin mixture at ratios of 25:75 (CH2), 50:50 (CH3) and 75:25 (CH4). Stress sweep test revealed that the sugar-containing chocolate (CH1) had a much higher complex modulus (G*) than the sugar-free samples, which could be attributed to the stronger interactive forces between the particles of CH1. It was also observed that an increase in inulin content reduced the length of the linear viscoelastic region, showing a decrease in yield stress as inulin content was raised and maltodextrin content was lowered. Results also indicated that the diffractogram of CH3 had sharper peaks than those of CH2 and CH4, revealing its more crystalline structure. The onset temperature of CH3 was much lower than that of the others, confirming the higher degree of crystallinity of this sample. The maximal wavenumber and the area under the curve of the –OH stretch band in the FTIR spectra of the three sugar-free samples were different from those of native inulin and maltodextrin. This revealed that inulin and maltodextrin might have undergone some physical interactions in the chocolate matrix. Replacement of sugar with inulin and maltodextrin elevated the chocolate hardness. CH4 was found to be the hardest sample which could be due to its higher solids packing intensity. Quantitative descriptive analysis demonstrated that CH2 was the closest sugar-free sample to CH1 with regards to mouth coating and chewiness, while CH3 was more similar to CH1 in terms of crumbliness.