Effect of soy proteins and emulsification-evaporation process on physical stability of lycopene emulsions

Abstract

Soy protein concentrate (SPC) was explored as an emulsifier in preparation of rice bran oil based lycopene emulsions. The SPC concentration and high pressure homogenization variables (pressure and number of passes) were optimized using response surface design obtained through Design-Expert Software. Twenty experimental combinations of SPC (0.25 to 1.25 %, w/v); homogenization pressure (10,000 to 30,000 psi) and number of passes (1 to 5) were carried out. The effect of process variables on particle size, polydispersity index and zeta (ζ) potential of lycopene emulsions was studied. The results obtained using analysis of variance and relative standard deviations of responses suggested that the maximum lycopene emulsification efficiency (85.85 ± 3.501 %), minimum particle size (346.90 ± 22.870 nm) and polydispersity index (0.27 ± 0.041) could be achieved at optimum conditions of 0.89 % (w/v) SPC at 25,000 psi in 4 passes through high pressure homogenizer. The emulsions prepared at optimum condition showed good physical stability in terms of ζ-potential (-42.32 ± 1.656 mV) with overall desirability of 0.8175