Encapsulation of flaxseed oil within native and modified lentil protein-based microcapsules

•Entrapment unmodified lentil protein isolate led to the lowest surface oil.•Encapsulation protected the oil from oxidation compared to the free oil.•Partially hydrolyzed lentil proteins were not effective as an encapsulating agent.

The physical properties of lentil protein-based maltodextrin microcapsules with entrapped flaxseed oil was investigated using native (n-LPI) and pre-treated (heated, un-hydrolyzed (u-LPI); and heated, hydrolyzed (h-LPI)) lentil proteins and as a function of oil load (10, 20 and 30% of total solids). Specifically, the moisture, water activity, surface oil and entrapment efficiency (EE) were assessed, along with droplet size and emulsion morphology of all formulations. Moisture (< 6%) and water activity (< 0.2) of all capsules were characteristics of dried powder ingredients. Light microscopy imaging of the emulsions, revealed that the h-LPI had slightly larger oil droplets than the n-LPI and u-LPI, which both appeared similar. Findings were confirmed by light scattering, where droplet sizes were 6.7, 4.2 and 4.2 μm for the h-LPI, u-LPI and n-LPI stabilized emulsions, respectively. Overall capsules prepared from h-LPI showed significantly higher surface oil and lower EE than both the n-LPI and u-LPI materials. Furthermore, as the oil content increased, overall surface oil became higher and EE became lower. Based on testing, capsules prepared using n-LPI with 10% oil loading was found to have the lowest surface oil content (~ 3.7%) and highest EE (~ 62.8%) for all formulations, and was subjected to an oxidative storage stability test over a 30 d period vs. free oil. The encapsulation process proved to be effective at lowering the production of primary and secondary oxidative products than free oil.