Effect of different process parameters and ultrasonic treatment during solid osmotic dehydration of jasmine for extraction of flavoured syrup on the mass transfer kinetics and quality attributes

This study investigates the effects of different process parameters (sugar dose, sugar size, and ultrasonic treatment time) on the solid osmotic dehydration (SOD) process of jasmine flowers and the physiochemical characteristics of syrup. The kinetics of moisture loss, solute gain, and effective diffusivity during SOD were predicted by fitting the experimental data with the Azuara model, Weibull model, and Fick second law model. The results showed that the high regression coefficient (R² > 0.9) and low χ² value represented the suitability of the Azuara model for predicting equilibrium water loss and solid gain and the Weibull model for predicting both moisture and solute fraction in jasmine under different process parameters during SOD. A relatively high sugar dose (120% w/w, fresh jasmine flower basis) and moderate sugar size (6–20 mesh) enhanced the moisture loss and solute uptake during SOD and produced more syrup. Furthermore, the high sugar dose (120% w/w) and small sugar size (40 mesh) enhanced the diffusion of polyphenols and flavonoids in jasmine to syrup. The mass transfer rate and syrup yield were increased, and more polyphenols, flavonoids, and antioxidant components were diffused to the syrup after applying the ultrasonic waves during SOD. Most flavour compounds of jasmine were effectively extracted by SOD under different process parameters, and alcohols (more than 68%) are the main flavour components of syrups, but the amount of major volatile compounds extracted was not affected by SOD process parameters.