Diminishing Marginal Utility of Cooling Rate Increase on the Crystallization Behavior and Physical Properties of a Lipid Sample |
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Authors: | K L Humphrey S S Narine |
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Affiliation: | (1) Alberta Lipid Utilization Program, Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Agricultural/Forestry Centre, Edmonton, AB, T6G 2P5, Canada |
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Abstract: | It is well established that variation of the rate of cooling (r) of a lipid sample is an effective tool to influence the crystallization process and effect changes in network structure and
physical functionality. However, the extent of the physical changes does not always justify the extent to which the cooling
rate must be altered. It is therefore important to understand the rates at which marginal changes in physical functionality
begin to diminish, and to understand the mechanisms which introduce such limitations. A commercially available cocoa butter
alternative, Temcote (Bunge Oils, Bradley, IL), was crystallized under cooling rates varying from 0.1 to 20 °C min−1. The growth mode and polymorphism of each sample was studied using DSC and X-ray diffraction (XRD). The hardness of the sample
was monitored using cone penetrometry and its solid fat content (SFC) evolution was monitored using a temperature controlled
pulse-NMR. The data demonstrates that the melting profile of the sample could be greatly manipulated over a relatively narrow
range of cooling rates. Large increases in cooling rate increase the final SFC of the sample by approximately 6%. Doubling
the cooling rate increases the hardness of the sample 50%. Variation of the cooling rate as a tool to modify physical functionality
of the network was found to be effective only for cooling rates lower than 5 °C min−1. |
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Keywords: | Cocoa butter alternatives Crystal structure Final physical properties Growth from melt Kinetics Rates of cooling |
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