Dynamics of moisture diffusivity in solid triacylglycerol matrices

- Fat systems with similar molecular compositions have different water vapor diffusivity values .
- Fats with relatively similar crystalline microstructure show different permeability values.
- Water movement in fats is governed by kinetic of migration and thermodynamic aspects.

The effects of lipid formulation in combination with two crystallization conditions, shearing and non-shearing, on the mechanism of water diffusivity were investigated. Five formulations of lipid which varied in fatty acid compositions, solid fat particles, and emulsifier levels were assessed at 5, 20, and 30 °C. Polarized light microscopy was used to study microstructural properties of the samples under dynamic and static conditions; and their moisture permeability was examined using gravimetric technique (ASTM E-96). All formulations and crystallization techniques were confirmed to have a large impact on the crystallization properties and dynamics of moisture migration. Dynamic crystallized samples showed altered structures with different patterns of crystalline clusters. Different values of water diffusivity suggested that shearing affected moisture diffusivity of the samples differently. This effect of shearing was more pronounced in the presence of lecithin. A higher migration rate was observed in sheared samples that contained higher amount of long chain saturated fatty acids.