Performance of partial replacement using natural emulsifier tailoring W/O-HIPEs
High internal phase emulsion (HIPE) is considered a promising fat replacer which might contribute to the reduction of trans- and/or saturated fat intake. Moreover, the feasibility to replace synthetic or semi synthetic ingredients by natural alternatives aiming food applications has been investigated. For this purpose, water-in-oil (W/O) HIPEs with a mixture of polyglycerol polyricinoleate (PGPR) and lecithin (LEC) as emulsifier were produced. The emulsions were formed using a rotor-stator at 14,000 rpm through dripping method with controlled aqueous phase flow rate of 2.5 ml/min, followed by homogenization at 20 MPa/5 MPa. Despite of the difficult to incorporate high volume fraction of dispersed phase (75% wt.), the chemical affinity of emulsifier seems to be decisive to define the type of emulsion produced. At fixed total amount of emulsifier (2% w/w), the LEC:PGPR ratios 0.5:1.5 and 1.0:1.0 showed similar droplet size and lower viscosity than emulsion with 2% PGPR, disclosing good kinetic stability. These outcomes also indicated a synergic interaction between LEC and PGPR in those aforementioned concentrations which can be affordable by the decay rate of interfacial tension. All the emulsions showed shear thinning behavior with high viscosity in low shear rate. In order to reduce droplet size of system, coarse emulsion was submitted to the high-pressure homogenization forming the fine emulsion. A drastic decrease in viscosity was observed (Newtonian fluids) and the confocal microscopy confirmed the phase inversion due to high input of energy leading to formation of oil-in-water fine emulsions. Hence, the rotor stator technique and partial PGPR replacement until 50% for natural emulsifier represented appropriate conditions for successful production of W/O-HIPEs. The created system could be applied in a range of food products with reduced fat level but remaining the desired texture properties. Besides that, tailored HIPEs would fulfill the consumers demand by healthy and clean labelling products.