Stabilization of caffeine-loaded nanoliposomes via chitosan coating and spray drying for application in food products

In this study, caffeine (CAF) was loaded into nanoliposomes (n-LPs) and chitosan-coated n-LPs, so called nanochitosomes (n-CTs). Among different CAF concentrations (1–5 mg/mL) and various chitosan coatings (0.1–1.0 mg/mL), n-LPs loaded with 4 mg/mL CAF (n-LPs-4) and coated with 0.4 mg/mL chitosan (n-CTs-0.4) exhibited the best physical properties, encapsulation efficiency (EE), and antioxidant activity. Under different storage conditions (4 °C, 25 °C, 70 °C, and freeze-thaw), freeze-thaw stress had the most detrimental effect on structural stability and unintended CAF release. However, chitosan coating layer increased its resistance to stress and controlled release in gastrointestinal conditions. To evaluate release mechanisms and kinetics, release data were fitted to zero-order, Kopcha, Korsmeyer-Peppas, and Higuchi models. CAF release kinetics in both simulated gastric and intestine conditions followed a Fickian diffusion mechanism. The release data fitted well with Kopcha and Korsmeyer-Peppas models, with R 2 > 0.92. The differential scanning calorimetry of CAF showed an endothermic peak at 237.85 °C. This peak was not observed after incorporation into n-LPs and n-CTs, indicating successful CAF encapsulation in these structures. Spray-drying of n-LPs-4 and n-CTs-0.4 resulted in particles with good production yield, physicochemical properties, moisture content, water activity, solubility, and color indices. FTIR analysis confirmed successful CAF loading inside n-LPs, chitosan placement on their membrane surface, and entrapment of particles within maltodextrin carriers. Morphological features revealed spherical particles in both n-LPs and n-CTs, along with instability, aggregation, and size-varied wrinkled structures (in powders) after spray drying. Finally, texture analysis and sensory evaluation of enriched Gaz (one of the traditional and conventional sweets in Iran) with CAF-loaded n-LPs-4 and n-CTs-0.4 powders indicated the production of a high quality and functional product with acceptable characteristics.