Impact of the droplet size of canola oil-in-water emulsions on the rheology and sensory acceptability of reduced-milk fat stirred yogurt

Abstract

A coarse canola oil-in-water (O/W) emulsion (dispersed mass fraction 0.1) was prepared by adding oil to whey protein hydrolysate (WPH)-citric pectin (CP) soluble complex (1\% total biopolymer weight; WPH to CP mass ratio 6:1; pH 4.25) aqueous phase using a high shear homogenizer (4000 rpm, 2 min). The coarse O/W emulsion was further homogenized to obtain emulsions (E-x) with different mean droplet sizes (4000, 3000, 120 and 60 nm). A full-fat yogurt (YC; 26 +/- 0.3 g milk fat L-1) was prepared from reconstituted whole milk powder (WMP, 3\% milk fat) and skim milk powder (SMP, 0.01\% milk fat). Reduced-milk fat yogurt (YEx 13 +/- 0.3 g milk fat L-1) variations were prepared from WMP + SMP + E-x, where E-x substituted 50\% of the milk-fat contained in YC. The viscosity and viscoelastic moduli were lower for YEx than for YC; the effect was more pronounced for E-60 and E-120. Aroma was non-significantly different between YC and YEx. A multivariate analysis showed that YEx overall acceptability was linked to taste and after taste attributes and to the viscosity perceived in mouth. The loss modulus showed anti-correlation directionality with the overall acceptance. The smaller mean droplet sized YEx exhibited the highest overall acceptability.