Anais do Simpósio Latino Americano de Ciências de Alimentos
Anais do 14 SLACA - Simpósio Latino Americano de Ciência de Alimentos

In the present study, the influence of enzymatic hydrolysis and the concentration of rice protein isolate (RPI) as emulsifier on the physicochemical properties of the linseed emulsion and the oxidative stability of the microparticles by spray drying were investigated. The protease Protamex® was used to obtain rice protein hydrolysates with degree of hydrolysis of 3% (DH3), 6% (DH6), 10% (DH10). The molecular weight distribution was further determined by SDS-PAGE and a decreased molecular weight with the progress in hydrolysis time was observed. All protein hydrolysates showed higher solubility than intact proteins over the pH 3-8, in which best performance was obtained by DH10 at pH 8 (19,03±0,21%). Surface charge analysis identified isoelectric point near pH4. Linseed oil-in-water emulsions stabilized by maltodextrin and protein hydrolysates with different concentrations (1 and 2 wt%) were characterized by oil droplet size, zeta-potential, creaming index (CI), emulsion stability index (ESI) and emulsion activity index (EAI). Emulsifying properties measured as EAI, ESI and CI increased significantly after proteolysis in both concentrations, whereas only DH3-2% (8,89±1,06 µm), DH6-2% (8,2±0,37 µm) and DH10-2% (9,02±0,55 µm) presented smaller droplets than RPI-2% (11,73±0,27 µm). The spray drying produced large microparticles, from 38,6±1,1 µm (DH3-1%) to 69,6±0,1 µm (DH3-2%), specially at 2% protein concentration. Despite the best emulsifying properties, DH10 microparticles showed lower microencapsulation efficiency (MEE) (34,5±3,1% at 1% and 38,5±1,9% at 2%) than DH3 (47,7±5,7% at 1% and 56,2±1,3% at 2%). In addition, after 18 days of peroxide value analysis, DH6 microparticles were able to protect the linseed oil with the lowest peroxide values (0,51±0,22 meq/kgoil at 1% and 0,22±0,02 meq/kgoil at 2%). Thus, despite higher degrees of proteolysis were able to improve emulsifying properties, GH6 provided the best antioxidation protection due to great core material coverage and GH3 produced less surface oil microparticles.