EFFECT OF THERMODYNAMIC PARAMETERS AND INTRINSIC PROPERTIES ON CRYSTALLIZATION KINETICS AND PHYSICAL PROPERTIES OF FATS

Objective 1: Synthesize and characterize fats with different contents of lauric, palmitic, and stearic acids.Objective 1a: Synthesize fats with different types and contents of saturated fatty acids (SFA).Objective 1b: Quantify the content of SFA and TAGs of the fats.This objective will synthesize fats with differing chemical composition that will be used in Objective 2 for crystallization experiments. The chemical composition of the fats in terms of content of SFA and TAG will be quantified. Fats synthesized in this objective will allow us to evaluate in a systematic manner how the type and content of SFA affect crystallization behavior in objective 2 when the fats are crystallized using various thermodynamic parameters. Fats will be custom-made using enzymatic interesterification or acidolysis to obtain lauric-, palmitic-, and stearic-based fats with different types (lauric, palmitic, and stearic fatty acids) and contents of total SFA (30%, 50%, 70%). Lauric-, palmitic-, and stearic-based fats will be used to represent fats with intermediate and long carbon chain lengths that show differing crystallization behavior that are commonly used in food systems, such as palm kernel-, palm-, and soybean-based fats, respectively. The content of SFA will be changed to represent contents commonly found in edible fats. An approximate 30, 50, and 70% SFA will be used to represent fats with low, intermediate, and high levels of SFA, respectively. Fats with these levels of SFA include palm kernel oil (~50% SFA), palm oil (~40% SFA), milk fat (~40% SFA), cocoa butter (~60% SFA), and commercially available shortenings with low levels of SFA (~32% SFA).This experimental design therefore utilizes 9 different fats.The FA and TAG composition of the fats will be quantified and the type and content of SFA will be calculated. Dr. Casimir Akoh will supervise the experiments included in Objective 1. Dr. Akoh has more than 37 years of experience in the interesterification of fats and more than 39 years of work in lipid chemistry and lipid biochemistry with over 300 publications on these topics. He has won many top research awards on lipid chemistry, low-calorie fats, and structured lipids synthesis (see biographical sketch), most recently the IFT Babcock-Hart Award (2018), AOCS Alton E. Bailey Award (2019), and AOCS A.R. Baldwin Distinguished Service Award (2022).Objective 2: Evaluate the effect of thermodynamic parameters and intrinsic properties on the crystallization kinetics and physical properties of the fats formulated in Objective 1.Objective 2a:Evaluate the effect of thermodynamic parameters and chemical composition on crystallization kinetics and physical properties of fats.Objective 2b: Characterize intrinsic properties of the fats, including viscosity, surface tension, heat capacity, and density.The purpose of this objective is to evaluate the crystallization kinetics and physical properties of fats with differing SFA and TAG composition crystallized using various thermodynamic conditions to explore how these factors (chemical composition and thermodynamic factors) together with other intrinsic properties of the materials affect fat crystallization. Fats will be crystallized using 10 crystallization temperatures (Tc) to achieve various levels of supercooling (low, intermediate, and high values of supercooling and driving forces) and to calculate thermodynamic parameters such as driving force of crystallization and activation free energies of nucleation, associated with fat crystallization as will be later described. Fats with different types and amounts of TAGs and SFAs will be crystallized using similar supercooling and driving forces. This will allow us to evaluate if the same supercooling and/or driving force will produce different crystallization behavior in fats with different chemical compositions (different activation free energies of nucleation). Intrinsic properties of the samples beyond chemical composition such as viscosity, heat capacity, density, and surface tension will also be measured at Tc. For a specific fat we expect to see changes in some of the intrinsic properties (viscosity, heat capacity, density) with Tc. Therefore, if fats crystallized using similar thermodynamic conditions result in different crystallization behavior, intrinsic properties can be used to explain the results. This experimental design will allow us to evaluate if differences in crystallization behavior of fats crystallized under the same thermodynamic conditions (supercooling and/or driving force) are due to intrinsic properties. For example, if a stearic-based fat is crystallized under similar thermodynamic conditions than a palm-based fat, but the palm-based fat crystallizes slowly and has a higher viscosity, the delay in crystallization can be explained by slow molecular diffusion caused by high viscosity.Objective 2 will be performed in Dr. Silvana Martini's laboratory. Dr. Martini will supervise the design and execution of the experiments. Dr. Martini has more than 25 years' experience in the evaluation of fat crystallization and on characterizing the physical properties of fats. She has published over 120 papers in these areas in peer-reviewed journals. Dr. Martini was the recipient of several international awards including Fellow of the American Oil Chemists' Society (AOCS); AOCS Timothy Mounts Award, and Young Scientist Award (Agricultural and Food Chemistry Division, American Chemical Society).