The effect of supercooling on crystallization of cocoa butter-vegetable oil blends |
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Authors: | David?Pérez-Martínez,C.?Alvarez-Salas,J.?A.?Morales-Rueda,J.?F.?Toro-Vazquez author-information" > author-information__contact u-icon-before" > mailto:toro@uaslp.mx" title=" toro@uaslp.mx" itemprop=" email" data-track=" click" data-track-action=" Email author" data-track-label=" " >Email author,M.?Charó-Alonso,E.?Dibildox-Alvarado |
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Affiliation: | (1) Facultad de Química, Departamento de Investigación y Posgrado en Alimentos (PROPAC), Universidad Autónoma de Querétaro, Querétaro, México;(2) Facultad de Ciencias Químicas, Centro de Invesigación y Estudios de Posgrado (CIEP), Universidad Autónoma de San Luis Potosí, Av. Dr. Manuel Nava 6, Zona Universitaria, 78210 San Luis Potosí, México |
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Abstract: | The solid fat content (SFC), Avrami index (n), crystallization rate (z), fractal dimension (D), and the pre-exponential term [log(γ)] were determined in blends of cocoa butter (CB) with canola oil or soybean oil crystallized at temperatures (T Cr) between 9.5 and 13.5°C. The relationship of these parameters with the elasticity (G′) and yield stress (σ*) values of the crystallized blends was investigated, considering the equilibrium melting temperature (T M o) and the supercooling (i.e., T Cr o−T M o) present in the blends. In general, supercooling was higher in the CB/soybean oil blend [T M o=65.8°C (±3.0°C)] than in the CB/canola oil blend [T M o=33.7°C (±4.9°C)]. Therefore, under similar T Cr values, higher SFC and z values (P<0.05) were obtained with the CB/soybean oil blend. However, independent of T Cr TAG followed a spherulitic crystal growth mechanism in both blends. Supercooling calculated with melting temperatures from DSC thermograms explained the SFC and z behavior just within each blend. However, supercooling calculated with T M o explained both the SFC and z behavior within each blend and between the blends. Thus, independent of the blend used, SFC described the behavior of G′eq and σ* and pointed out the presence of two supercooling regions. In the lower supercooling region, G′eq and σ* decreased as SFC increased between 20 and 23%. In this region, the crystal network structures were formed by a mixture of small β′ crystals and large β crystals. In contrast, in the higher supercooling region (24 to 27% SFC), G′eq and σ* had a direct relationship with SFC, and the crystal network structure was formed mainly by small β′ crystals. However, we could not find a particular relationship that described the overall behavior of G′eq and σ* as a function of D and independent of the system investigated. |
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Keywords: | Avrami cocoa butter crystallization elastic modulus polymorphism rheometry yield stress |
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