The possibility to control lipid crystallization is of great importance to conferring peculiar technological and sensory properties of many foods. Tempering, shear and mixing, seeding and additive application, and, more recently ultrasonication, are traditionally applied to drive and control fat crystallization. Besides these processing interventions, reduced attention has been paid to the possibility of steering lipid crystallization by hyperbaric treatments. In this work, lipid crystallization under moderate pressure treatments was studied in binary systems containing sunflower oil (SO) and increasing concentrations (70, 80, 90, 100 %, w/w) of palm stearin (PS). To this aim, lipid blends were inserted in plastic pouches, melted at 70 °C for 30 min, and positioned in the chamber of a hyperbaric plant to carry out the crystallization. Samples were allowed to cool and crystallize in the chamber maintained for 24 h at 20 °C and 200 MPa. After the treatment, samples were removed and analyzed after a 24-h period to allow network relaxation. Samples were characterized for mechanical (compressive dynamometry), rheological (oscillatory rheology), thermal (differential scanning calorimetry), microstructural (optical microscopy), and morphological properties (synchrotron X-ray diffractometry). Samples crystallized at atmospheric pressure and room temperature (0.1 MPa) were used as references. Crystallization under pressure significantly increased the firmness of SO/PS systems. Accordingly, hyperbarically-crystallized samples showed elastic behavior and critical stress significantly higher than that of control samples, indicating an increased capacity to tolerate external mechanical stress. This was attributed to the formation of smaller and homogeneously distributed crystallites with different crystal morphology. This work clearly shows that the application of moderate pressure treatments could be effective in steering lipid crystallization behavior. The proposed technology could be particularly interesting in the industrial framework, being an energy-efficient strategy.
Effect of moderate hyperbaric treatments on lipid crystallization
Luisa Barba;
2023
Abstract
The possibility to control lipid crystallization is of great importance to conferring peculiar technological and sensory properties of many foods. Tempering, shear and mixing, seeding and additive application, and, more recently ultrasonication, are traditionally applied to drive and control fat crystallization. Besides these processing interventions, reduced attention has been paid to the possibility of steering lipid crystallization by hyperbaric treatments. In this work, lipid crystallization under moderate pressure treatments was studied in binary systems containing sunflower oil (SO) and increasing concentrations (70, 80, 90, 100 %, w/w) of palm stearin (PS). To this aim, lipid blends were inserted in plastic pouches, melted at 70 °C for 30 min, and positioned in the chamber of a hyperbaric plant to carry out the crystallization. Samples were allowed to cool and crystallize in the chamber maintained for 24 h at 20 °C and 200 MPa. After the treatment, samples were removed and analyzed after a 24-h period to allow network relaxation. Samples were characterized for mechanical (compressive dynamometry), rheological (oscillatory rheology), thermal (differential scanning calorimetry), microstructural (optical microscopy), and morphological properties (synchrotron X-ray diffractometry). Samples crystallized at atmospheric pressure and room temperature (0.1 MPa) were used as references. Crystallization under pressure significantly increased the firmness of SO/PS systems. Accordingly, hyperbarically-crystallized samples showed elastic behavior and critical stress significantly higher than that of control samples, indicating an increased capacity to tolerate external mechanical stress. This was attributed to the formation of smaller and homogeneously distributed crystallites with different crystal morphology. This work clearly shows that the application of moderate pressure treatments could be effective in steering lipid crystallization behavior. The proposed technology could be particularly interesting in the industrial framework, being an energy-efficient strategy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
