Effect of storage time on physical properties of sonocrystallized all‐purpose shortening

Abstract

The purpose of this study was to determine the effect of high-intensity ultrasound (HIU) on the physical properties of an all-purpose shortening and to evaluate how these properties changed during storage (48 hr; 4, 12, and 24 weeks) at 5 °C and 25 °C. Samples were crystallized at 30 °C for 60min with and without the application of HIU (20kHz; 3.2mm-diameter tip, 168µm amplitude, 10 s). After crystallization, physical properties, such as hardness, elasticity, melting behavior, and solid fat content (SFC), were measured. These properties were also measured during storage. The effect of HIU was significant in changing the SFC, hardness, G' and G'', melting enthalpy, and microstructure of the samples. After 60min of crystallization, the sonicated samples had higher values of SFC, hardness, elasticity, and melting enthalpy than the ones obtained without sonication (P <0.05). Changes in these physical properties were associated with the microstructure of the samples since sonication generated smaller, more uniformly sized crystals as well as increased the number of crystals. No differences were observed in the G' of the sonicated samples stored at 25 °C as a function of storage period. The G' of the nonsonicated samples increased until 12 weeks of storage and was maintained up to 24 weeks, suggesting that sonication speed up the formation of a stable crystalline network. Samples stored at 5 °C showed higher value in hardness, G' and G'', and SFC than the ones stored at 25 °C. PRACTICAL APPLICATION: High-intensity ultrasound (HIU) has been widely used as an additional tool to change the crystallization behavior in various lipids; however, the long-term storage effect of HIU has not been studied before. This research evaluates the effect of HIU on the physical properties of a palm-based shortening stored up to 24 weeks at two different temperatures (25 and 5 °C). The application of HIU may help increase the stability of lipid during storage.