Effect of CO2 Bubbles on Crystallization Behavior of Anhydrous Milk Fat

A study was designed to observe the effect of bubbles created from dissolved CO2 (0–2000 ppm) on crystallization and melting behavior, fat polymorphs, microstructure, and hardness of anhydrous milk fat (AMF) under nonisothermal crystallization conditions. Calculated amounts of dry ice were added to generate 2000 ppm CO2 at low partial pressure, and an ultrasound (205 kHz, 10 s; US) treatment was delivered at 35 °C through a noncontact metal transducer on the molten AMF to generate bubbles (~500 nm) of CO2. The generated CO2 bubbles were found to induce a higher onset of crystallization temperature during cooling from 35 to 5°C at the rate of 0.5°C min?1. The changes in crystallization behavior owing to the generation of a smaller and significant number of TAG crystals also increased the hardness of the AMF at room temperature and refrigerated conditions. The work suggested the potential use of CO2 nanobubbles derived from the dry ice with the emission of low power US to control the crystallization behavior and thereby the physical properties of milk fat-containing dairy products.