The effects of physical properties of sorbitol powder on the quality of sugar-free chewing gum

In this doctoral study, the effects of the physical properties of sorbitol, used as a sugar substitute, on the quality of sugar-free chewing gum were comprehensively investigated. The primary objective of the research was to scientifically elucidate the role of key physical parameters of powdered sorbitol -such as particle size distribution (D10 and D50) and bulk density- on the textural attributes, sensory characteristics, and shelf-life performance of the final product. In the experimental work, sorbitol powders with high gamma crystal content (95–100%) were produced under different crystallization conditions. These samples were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and particle size distribution (PSD) analysis, followed by their application in the production of sugar-free stick gum, where they were evaluated in terms of texture, moisture, sensory properties, and storage stability. The experimental design was developed using the response surface methodology (RSM), where 20 different gum formulations were created by varying D10 (30–120 µm), D50 (150–250 µm), and bulk density (0.45–0.55 g/cm³). The results indicated that formulations with D10 values of approximately 75–90 µm, D50 values of 200–225 µm, and bulk density within 0.50–0.55 g/cm³ demonstrated superior mechanical and sensory performance. Hardness tests showed that these formulations fell within the target range of 10-12 N, and sensory panel evaluations confirmed high ratings in terms of sweetness intensity, chewability, and non-stickiness. Among the samples, the D97 sugar-free stick chewing gum -optimized via RSM and characterized by D10 ≈ 90 µm, D50 ≈ 225 µm, bulk density ≈ 0.55 g/cm³, hardness value of 15.8 N, and moisture content of 3.9%- was identified as the highest-performing formulation in terms of both physical and sensory properties. Owing to its high gamma crystallinity, optimized particle size distribution, and homogeneous structure, D97 maintained its textural stability and moisture control effectively throughout the storage period. In conclusion, this study demonstrates that the physical properties of sorbitol, beyond its chemical composition, play a critical role in determining the quality of sugar-free chewing gum. The findings highlight the importance of particle engineering in industrial formulation development and offer original, practical insights that can guide both academic research and commercial production practices.