Effect of High Intensity Ultrasound on Crystallization Behavior and Functional Properties of Lipids
The effects of high intensity ultrasound (HIU) on the crystallization behavior and functional properties of shortenings were evaluated. HIU was applied to different shortenings such as interesterified soybean oil (IESBO), multi-purpose commercial shortening, palm oil, and palm stearin. The functional properties measured include crystal morphology, solid fat content, melting profile, viscoelastic properties, hardness, and polymorphism. Different experimental set-ups were evaluated including a
... tic batch system, a temperature cycling design, and flow cell system. Results showed that HIU generated harder material on IESBO, commercial shortening, and palm oil with more uniform and smaller crystal size, sharper melting profile, and higher elasticity. No chemical changes on triacylglycerol (TAG) and fatty acids were observed on IESBO under the sonication conditions used in this dissertation. Application of HIU maintained the texture of the commercial shortening that was subjected to temperature fluctuations, especially when HIU was applied before changes in temperature occurred. When sonication was applied in a flow-cell system lower power levels applied in a continuous manner was proved to be the most effective at inducing crystallization of palm oil. Research also showed that pulse irradiation of sonication and higher flow rates could be used to decrease the thermal effects generated by higher power levels of HIU. In addition, HIU was used in a highly saturated fat (palm stearin) at low power levels with long durations to delay lipid crystallization and generate a softer material. All the research findings suggest the great potential use of HIU in shortening production and food processing to improve the texture and its stability, as well as other functional properties.