The cooling rate effect on the microstructure and rheological properties of blends of cocoa butter with vegetable oils

• Published in: Food research international 2007, Vol.40 (1), p.47-62
• Main Authors: Pérez-Martínez, David, Alvarez-Salas, C., Charó-Alonso, M., Dibildox-Alvarado, E., Toro-Vazquez, J.F.
• Format: Article
• Language: English
• Subjects: blended foods; canola oil; Cocoa Butter; Cooling rate; crystal structure; crystallization; crystals; differential scanning calorimetry; dispersions; Fractals; glass transition temperature; lipid content; Microstructure; rheological properties; Rheometry; solid fat content; solids; soybean oil; supercooling; triacylglycerols; viscoelasticity
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2006.07.016

The elasticity ( G′) and yield stress ( σ ∗) of blends of cocoa butter (CB) in vegetable oils (i.e., 30% CB/canola and 30% CB/soybean oil) crystallized at temperatures ( T Cr) between 9.5 °C and 13.5 °C and two cooling rates (1 °C/min and 5 °C/min) were determined, evaluating their relationship with parameters associated with the formation and structural organization of the crystal network [i.e., solid fat content (SFC), Avrami index, crystallization rate, fractal dimension ( D)]. The results showed that T Cr and cooling rate had a different effect for each blend on the three-dimensional organization of the crystal network, and on the proportion and size of β′ and β crystals. Thus, under low supercooling conditions at both cooling rates, the crystallized CB/canola oil blend was formed by a mixture of small β′ and large β crystals that provided high G′ and σ ∗ at low SFC (i.e., 20.5–20.9%) and D (i.e., 1.66–1.72) values. The CB/soybean oil blend achieved similar G′ and σ ∗ independent of cooling rate only at high supercooling. In this case, the crystal network was formed mainly by small β′ crystals with SFC (i.e., 25.4–26.3%) and D (i.e., 2.86–2.79) values higher ( P < 0.05) than in the CB/canola oil blend at low supercooling.