The Use of Cooling Rate to Engineer the Microstructure and Oil Binding Capacity of Wax Crystal Networks

Abstract

The effects of cooling rate during melt crystallization of rice bran wax, sunflower wax, candelilla wax and a commercial peanut butter stabilizer in peanut oil were evaluated and correlated to their oil binding capacity. Rapid cooling upon crystallization decreased crystal length, decreased network pore area fraction, increased the fractal dimension of the crystal network, and lead to an increase in the oil binding capacity. Oleogels structured using 1 % sunflower wax exhibited the highest oil binding capacity, followed by candelilla wax and rice bran wax gels. The oil binding capacity of the commercial stabilizer was the lowest, but could be improved by crystallizing the material under high cooling rates. Linear correlation analysis revealed that the network fractal dimension decreases as pore area fraction increases, which was correlated to a greater oil loss. In general, the oil binding capacity of a gel can be significantly improved if the pore area fraction is decreased below 96 %, demonstrating how the fractal dimension and pore area fraction of a gel network can be modulated to tailor oil binding capacity.