INFLUENCE OF HYDROLYZED RICE PROTEIN ON ANTHOCYANIN RETENTION IN GRAPE JUICE MICROPARTICLES OBTAINED BY SPRAY DRYING

There is growing interest in the use of plant proteins for film formation and stabilization of compounds of interest. However, in order to these proteins can compete with animal proteins, it is necessary to improve their encapsulation properties. This study aimed to evaluate if the enzymatic hydrolysis is a viable alternative to improve the encapsulation properties of plant proteins. For this, rice bran protein hydrolysates (RPH) in combination with maltodextrin (MD) were used as encapsulating agents (CA) in the microencapsulation of grape juice by spray drying, in order to protect anthocyanins during processing. Feeding solutions (FS) were prepared, containing 1.00 g CA/g of soluble solids of the juice and the protein:MD proportion of 15%. Different degree of hydrolysis (DH) of the protein was studied: 0% (control, represented by intact protein), 5%, 10%, and 15%. The feed solutions were dried in a laboratory-scale spray dryer, using a two-fluid atomizer nozzle with a diameter of 1.0 mm and inlet air temperature and FS temperature of 140±2 °C and 25±2 °C, respectively. The outlet air temperature was 79±2 °C. The pH differential method was used to measure total and retained anthocyanins within the microparticles by UV light spectrophotometer. The results were expressed in percentage, using cyanidin-3-glycoside as reference anthocyanin. As results, the control sample presented 22.4±1.1% of internal retention and 30.3±4.0% of total retention of anthocyanins, while the sample with RPH with DH 15% reached 36.1±0.3% and 48.6±6.5% of internal and total retention, respectively. Higher DH means smaller proteins molecules, which may have favored their migration by diffusion mechanism to the particle surface with posterior deposition. As consequence, a greater preservation of anthocyanins was observed due to this protective protein rich layer.