Altering Functional Properties of Fats Using Ultrasound Jessica Leis KNH 404

Information obtained from the Journal of Food Science, Issue 74 Suzuki, A., Lee, J., Padilla, S., & Martini, S. (2010).

Main Objective To find alternative lipid sources to provide the same adequate functional properties for foods previously containing trans fatty acids using power ultrasound techniques to alter fat crystallization

Ultrasound Technique Ultrasound techniques are those that use sound waves using frequency just above human hearing detection, or greater than 20 kHz. Researchers used power ultrasound, or high frequency ultrasound (HIU) at a range of 20 to 100 kHz to examine its ability to change the physiochemical properties of lipid materials High frequency ultrasound can be used for generating and inducing chemical reactions to alter crystallization behaviors and functional properties

Amount of crystallization Fats Used Anhydrous milk fat (AMF) Palm kernel oil (PKO) All-purpose shortening (Sh) To Observe: Hardness Amount of crystallization Melting behavior To determine if these fats would be acceptable lipid substitutes

Experimentation Methods & Materials Crystallization Misonix S-3000 sonicator operating at an acoustic frequency of 20 kHz for 10 seconds using 50 watts of electrical power Crystallization kinetics were monitored throughout 1.Crystallized at a fast cooling rate of 10 degree Celsius per minute at different crystallization temperatures 2. Heated at 80 degrees C (176 degrees F) for 30 minutes to allow for complete triacylglyceride (simple fat containing 3 FA’s esterified to glycerol – most common) melting 3. Placed in crystallization cell and stirred with magnetic stirrer 4. Upon cooling finish, HIU was applied 5. Samples kept under HIU upon final cooling temperature for 90 minutes

Experimentation Methods & Materials Polarized Light Microscopy (PLM) Equipped with digital camera DSC-2910 To determine melting profile of crystallized lipids Observations taken every 5 minutes during 90 minutes DSC – 7 to 15 milligrams in airtight aluminum pan

Experimentation Methods & Materials TA-XT plus Texture Analyzer To determine hardness Samples were compressed at a constant speed of 5 mm/s using a compression strain of 25 percent All experiments were run 3 times. Data was computed using an accredited software program Cylindrical tubes (1 centimeter in diameter) were stored at 5 degrees Celsius for 24 hours before textural analysis Hardness was defined as the maximum peak force obtained during the first compression

Results Crystallization HIU could successfully induce crystallization and smaller crystal size in AMF, PKO Sh crystals were significantly smaller AMF – however, very dependent on supercooling

Results Texture – Hardness PKO hardness decreased the most, followed by AMF and then Sh Hardness decreased as crystallization temperature increased

Melting Profile and Enthalpy Results Melting Profile and Enthalpy Enthalpy - the energy absorbed from the lipid crystals when they melt AMF: when HIU was applied, the enthalpy of the crystal network formed was higher due to size of crystals (not amount) PKO: increased upon crystallization conditions for, meaning HIU is promoting crystallization Sh: no significant changes when HIU was applied

Conclusions The lipid melting profile of a lipid network depends on the amount of crystallized material and the size of the crystals The higher the melting profile, the better the mouthfeel and palatability Melting behavior is important for mouthfeel and palatability

Conclusions AMF under HIU had a sharper and steeper melting profile PKO samples under HIU melted faster contributing to a broader melting profile Sh results were similar to AMF Indicates a lower percent of solid at a constant temperature High frequency ultrasound methods have the potential to become an additional processing tool to modifying the textural, structural, and melting properties of lipids to replace trans fatty acids.

Trends in the Research Effect of lipid oxidation/oxidative stability on the quality of the food Storage time and temperature Methods to reduce lipid oxidation Irradiation Replacement fats Interesterified fats with trans-free substrates High intensity ultrasound Replacing trans fatty acids with alternative substances Antioxidant effects on lipid stability Needs to be controlled to enhance and maintain a quality product. For example, in the experiments examining lipid in California almonds and hulless barley kernels, storage time and temperature were key variables in determining the rate of lipid deterioration and its effect on the product. Reduce the opportunity for the lipids to go rancid. Addressing health concerns related to heart disease, etc. The effect of green tea extracts on biscuit lipid fraction oxidation and antioxidants on salmon jerky were examined as having positive effects on maintaining lipid stability and product quality