Effect of heating and homogenization on the stability of coconut milk emulsions

The effects of homogenization and heat treatment on the colloidal stability of coconut milk were studied. Fresh coconut milk (15% to 17% fat, 1.5% to 2% protein) was extracted and stored at 30°C before homogenization at 40/4 MPa (stage I/stage II). Both homogenized and non-homogenized samples were heated at 50°C, 60°C, 70°C, 80°C, and 90°C for 1 h. Homogenization reduced the size of the primary emulsion droplets from 10.9 to 3.0 μm, but increased the degree of flocculaution, presumably via a bridging mechanism. This flocculation was also responsible for increased viscosity of the homogenized samples. Heating increased the degree of flocculauon in both non-homogenized and homogenized samples. A slight amount of coalescence was also observed after heating above 80°C. All samples creamed after 24 h of storage, but the heated samples formed a larger cream layer, presumably because the flocculated droplets packed together less efficiently. Optical microscopy was used to confirm the combination of flocculation and creaming responsible for changes in coconut milk quality. The information obtained from this study provides a better understanding of the emulsion science important in controlling coconut milk functionality.