Progress 08/15/23 to 10/03/24
Outputs
Target Audience:The target audience for this annual report are fat producers that are trying to develop healthier fats with improved physical properties. The target audience will be able to learn to to synthesize palm-based fats with specific triacylglycerol compositions. They will also learn how thermodynamic factors affect the crystallization behavior of commercially available fats. The broader public will be able to access fat products with better nutritional properties and improved physical properties. Changes/Problems:This grant is being transferred from USU to UNL since Dr. Martini, the PI of this grant has changed institutions. The transfer was initiated in September 2024. The experiments planned for objective 2 will be dependent on the time when this transfer is finalized. What opportunities for training and professional development has the project provided?This project provided training to two PhD students (1.0 FTE, Ityotagher Philip Aondoakaa, and Xinyu Liu) and one MS student (0.5 FTE, Nabila Adjum). Graduate students designed, organized, and performed the experiments. They were responsible for data collection and data interpretation. Students gained experience in the use of various techniques commonly used in the characterization of physical properties of fats and in interesterification reactions. These techniques include differential scanning calorimeter, pulsed nuclear magnetic resonance, rheometer, polarized light microscopy, X-ray diffraction. How have the results been disseminated to communities of interest?Nabila Anjum (the MS student in this project) presented her results in a poster format during the 2024 AOCS Annual Meeting and Expo. She is also writing her first paper to be submitted by December 2024 to a peer-reviewed journal. What do you plan to do during the next reporting period to accomplish the goals?Dr. Akoh will continue with the upscaling of the stearic- and palmitic-based samples that will be sent to Dr. Martini's laboratory and will optimize the production of lauric-based samples. Continuation of this proposal will be limited by the availability of funds. This grant is being transferred from USU to UNL due to a change in positions for Dr. Martini and experiments planned for objective 2 will be dependent on the time when this transfer is finalized.
Impacts
What was accomplished under these goals?
As part of Objective one, stearic- and palmitic-based fats were synthesized by Dr. Casimir Akoh's laboratory using enzymatic acidolysis. The goal is to synthesize palmitic- and stearic-based fats with total saturated fatty acids (SFAs) contents of 30, 50, and 70%. A small-scale enzymatic acidolysis reaction using 1 g of soybean oil (SO) and free fatty acid (FFA) was carried out to establish optimum reaction conditions, such as temperature and substrate molar ratios, that will yield modified fats with total SFAs contents of 30, 50, and 70%. The substrate (SO to acyl donor) molar ratios were 1:1, 1:2, 1:6, 1:10, 1:15, and 1:20 for free palmitic acid (C16:0), and 1:0.5, 1:5, and 1:10 for free stearic acid (C18:0). The immobilized lipase Lipozyme® TL IM load was 10% of the total weight of substrates. Linear interpolation was used to estimate molar ratios that would yield modified fats with expected 30, 50, or 70% total SFAs. The targeted C16:0- or C18:0-rich total SFAs level (y) was plugged into respective linear equations, and the required C16:0 or C18:0 molar ratio (x) was determined. When C16:0 is the acyl donor, the 1:0.6356, 1:9.7562, and 1:20.1480 molar ratios are expected to yield fats with 30, 50, and 70% total SFAs, respectively. With C18:0 as the acyl donor, 1: 1.0676 and 1:5.9790 molar ratios are expected to yield fats with total SFAs of 30 and 50%, respectively. In addition to the activities described above related to Objective one, optimization of appropriate techniques to measure induction times of crystallization was performed at Utah State University in Dr. Silvana Martini's laboratory. This study evaluates the activation free energy of crystallization of three fats by measuring induction times (λ) of crystallization. Three methods were used to measure λ (a) through SFC vs. time (discrete method), (b) fitting SFC vs. time to the Gompertz equation, and (c) using differential scanning calorimetry (DSC). When measuring SFC as a function of time Tc for IESBO and PKO ranged from 30-38°C, while for IEPO, Tc were between 22-31°C. Induction times for IESBO using the discrete method was between 2 min (Tc=30°C, ΔGc 7.2KJ/mole) and 75 min (Tc=38°C, ΔGc 17.1KJ/mole). While the Gompertz equation resulted in λ=0.23 min (Tc=30°C, with ΔGc 9.2KJ/mole) and λ=25.21 min (Tc=38°C, with ΔGc 21.8KJ/mole). Similar λ were observed for PKO at Tc 30°C (λ=2 min) but lower ΔGc of 1.99KJ/mole. At Tc=38°C longer λ was observed (λ=90 min, ΔGc of 11.5KJ/mole) (discrete value). When using the Gompertz equation a good fit was found for Tc between 31°C-37°C with λ=5-287 min (ΔGc=3.4-12.5KJ/mole). These results show that more energy must be delivered to IESBO samples to crystallize compared to PKO for the same Tc. For IEPO at Tc 22-31°C the λ=1-90 min (ΔGc=6.8-17.8KJ/mole) through the discrete method. While λ=2.6-37.2 min (ΔGc=6.5-14.2KJ/mole) when the Gompertz method was used. When λ were calculated with the DSC method higher Tc were used. Tc were between 37-43°C, 30-35°C, and 33-35.5°C and ΔGc values between 4.1-10.5KJ/mole, 1.4-2.31KJ/mole, and 0.5-0.6KJ/mole for IESBO, IEPO, PKO, respectively. Using the DSC method, for a supercooling of approximately 10.7°C ΔGc were 9.5KJ/mole, 2.31KJ/mole, and 0.5KJ/mole for IESBO, IEPO, and PKO, respectively. This suggests that even for the same supercooling, more energy is required to crystallize IESBO, followed by IEPO and the least energy is required for the PKO sample. This is surprising considering that the driving force of crystallization for this supercooling is 4.3, 2.4, and 4.6J/g for the IESBO, IEPO, and PKO, respectively. Overall, these results indicate that the best method to measure induction times of crystallization and therefore activations free energies of nucleation is the p-NMR method when the data is fitted using the Gompertz equation.
Publications
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