Effect of agar and konjac on physicochemical properties and stability of Coffea liberica–infused marshmallows

This study investigated the physicochemical effects of incorporating agar and konjac powders into Coffea liberica–infused marshmallows as alternatives to gelatin. The usage of the plant-based gelling agents also addresses dietary preferences such as halal and vegan requirements. Various analyses, including total phenolic content (TPC), texture profile, color, moisture content, water activity, and scanning electron microscopy (SEM), were conducted during storage for 6 days. Results showed that marshmallows containing Coffea liberica had significantly higher TPC (p<0.05). In particular, the marshmallow containing 1.02% agar with Liberica coffee brew (MAC) exhibited consistent physicochemical properties, while the marshmallow containing 0.51% agar and 0.51% konjac with Liberica coffee brew (MKAC), exhibiting the highest value (0.8740 mg GAE/g) as compared to the control containing gelatin (0.2294 mg GAE/g). Texture profile parameters—including hardness, gumminess, chewiness, and resilience—increased consistently across all formulations over 6 days of storage. Color analysis showed a strong positive correlation (r = 0.977) between hydrocolloid b* values and marshmallow lightness (L*), indicating that greater yellowness was associated with lighter-colored marshmallows. It indicates that the yellowness of the hydrocolloid has a direct impact on marshmallow lightness, which is crucial for controlling product appearance. Significant differences (p<0.05) were observed in moisture content, whereas water activity showed no significant variation (p>0.05) throughout storage. This may be due to the changes in total water content that did not affect the amount of free water responsible for water activity. SEM analysis differentiated the hydrocolloid-based samples through variations in surface roughness, smoothness, and pore distribution. Overall, agar and konjac powders, together with Coffea liberica, significantly influenced the physicochemical properties of the marshmallows, demonstrating their potential as plant-based alternatives for use in the confectionery industry