Characterization of Structural and Mechanical Properties of Fat Crystallized Under High Pressure
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Date
2017-03
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Publisher
ACS Publications
Abstract
Pressure is a thermodynamic parameter that can accelerate lipid crystallization. However, there is still limited understanding on how pressure can be used to modify lipid crystalline network and ultimately its functionality for food texture applications. The objective of this study was to characterize structural and mechanical properties of a fat model crystallized under different high pressure processing conditions. A fat model consists of fully hydrogenated soybean fat and soybean oil (3:7 ratio) was crystallized under pressures (100-600 MPa) at maximum temperature under pressure of 80 ºC using a laboratory scale high pressure unit. The samples were melted, allowed to reach pre-determined initial temperature, pressurized to 80 ºC at the targeted pressure and cooled under isobaric condition at 30 ºC for 10 min. The crystallized samples were characterized using X-ray diffraction, small angle X-ray scattering, polarized light microscopy, and rheometer. Three groups of crystal morphologies were observed. At low pressure levels, a mixture of large and small microstructures (Group I) crystallized during isobaric cooling led to in low storage modulus, G’ (0.74 x 103 - 1.16 x 103 Pa). Above 300 MPa, high density of small microstructures (Group II) crystallized during adiabatic compression substantially increased G’ (1.74 x 103 - 1.84 x 103 Pa). The presence of smaller nanostructures of β crystal was documented in all samples crystallized under high pressure from the melt compared to a mixture of metastable β’ and β crystals in control samples and crystallized at atmospheric condition prior to pressurization. In conclusion, high pressure treatments improve texture properties of fat by modifying structural properties of the fat crystal network as affected by nucleation rate.
Description
Poster Division: Engineering, Math, and Physical Sciences: 1st Place (The Ohio State University Edward F. Hayes Graduate Research Forum)
Keywords
high pressure, nanostructure, microstructure, nucleation, kinetic of crystallization