Effect of lentil proteins isolate concentration on the formation, stability and rheological behavior of oil-in-water nanoemulsions.

The formation, stability and rheology of 5wt% oil-in-water nanoemulsions as a function of lentil protein isolate concentration (0.5-5wt%) at pH 3.0 was investigated for 28days. All nanoemulsions, except 1wt% protein, showed bimodal droplet size distribution where the larger diameter peak was ascribed to protein aggregates and entrapped oil droplets. The average droplet size for all nanoemulsions measured from the lower diameter peak ranged from 161 to 357nm, which did not change over 28days. Stable flowable nanoemulsions were formed at 1-2wt% protein concentrations. Nanoemulsions with 3 and 5wt% protein formed strong non-flowable gels which showed a two-step yielding behavior during strain-sweep rheology, indicating gel formation by interconnected clusters of proteins and oil droplets. This study demonstrated that lentil protein has a potential to be utilized as an emulsifier in nanoemulsions, as well as in the formation of emulsion gels at higher protein concentrations.