Effect of l-methionine and l-lysine combined with OSA-modified starch on physical properties and oxidative stability of linseed oil powders

The study aimed to analyze the effects of l-methionine (MET) and l-lysine (LYS) combined with octenyl succinic anhydride-modified starch (OSA-MS) on the emulsion’s physical properties, encapsulation efficiency (Ef), powder’s physical properties, and oxidative stability of linseed oil (LO) powders produced by freeze-drying. Therefore, five formulations/emulsions were produced as follows: P1 (LO + OSA-MS, 1:3); P2 (LO + MET + OSA-MS, 1:0.3:2.7); P3 (LO + MET + OSA-MS, 1:0.6:2.4); P4 (LO + LYS + OSA-MS, 1:0.3:2.7); P5 (LO + LYS + OSA-MS, 1:0.6:2.4). From the creaming index results, it was found that all emulsions presented good stability after 24 h of analysis, with no phase separation. LYS presented an average value of antioxidant capacity toward the DPPH radical of 30.40% and MET an average value of 25.16%. The powders presented low moisture values (≤4.03%), hygroscopicity (≤0.1327 kg/kg), poor flowability, and high cohesiveness. Increasing the LYS (polar) content resulted in a significant decrease in the dissolution time of the powders. The Ef decreased with the addition of MET (Ef of ~52.90%) and increased with the increase of the LYS content (Ef between 72.23 and 94.85%), compared to the formulation containing the OSA-MS as encapsulant agent (Ef = 71.72%). Based on the results of hexanal content, the positive effect of the amino acids on the oxidative stability of the powders was observed. The addition of MET and LYS in a mass proportion of 7.5% (formulations P2 and P4), resulted in a significant increase in the oxidative induction time of LO powders of ~24.3%, compared to the formulation containing only the OSA-MS (P1).