High internal phase emulsions stabilized by the lentil protein isolate (Lens culinaris)

Abstract

This work investigates the stability of high internal phase emulsions (HIPEs) made from 75 % (w/w) soybean oil and 25 % lentil protein isolate dispersion (LPI concentration of 2 %, 4 %, and 6 %, w/w) at pH 3 and 7. Soybean oil is rich in polyunsaturated fatty acids (linoleic and oleic), and lentil protein is rich in essential amino acids such as lysine and leucine. The LPI dispersions were characterized by SDS-PAGE, intrinsic fluorescence, zeta potential measurement, solubility determination, particle size distribution, and differential scanning calorimetry. The HIPEs were characterized for oil loss after centrifugation, droplet size distribution, morphology, rheology, Turbiscan stability index, and lipid oxidation over 60 days of storage at 25 °C. HIPEs containing 4 % and 6 % LPI presented lower values of droplet size distribution (31.70 ± 0.00 µm and 35.57 ± 0.00 µm at pH 3, and 18.55 ± 0.97 µm and 16.53 ± 0.86 µm at pH 7, respectively) and oil loss (2.61 ± 0.33 % and 1.90 ± 0.67 % at pH 3, 1.80 ± 0.14 % and 1.40 ± 0.50 % at pH 7, respectively). These HIPEs showed elastic behavior, creamy visual appearance, and better stability than HIPEs with lower LPI concentrations. These results show that HIPEs can be stabilized solely with LPI at concentrations of 4 % and 6 % at pH 3 and 7. In addition, these HIPEs can be used as a potential substitute for saturated fat in foods.