The effect of supercooling on crystallization of cocoa butter‐vegetable oil blends

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°) and the supercooling (i.e., T Cr°− T M°) present in the blends. In general, supercooling was higher in the CB/soybean oil blend [T M°= 65.8°C (±3.0°C)] than in the CB/canola oil blend [T M°= 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°e xplained 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.

Thermo‐mechanical properties of candelilla wax and dotriacontane organogels in safflower oil

“…Micronized high-purity CW obtained from E. cerifera was supplied from Multiceras (Monterrey, Mexico) and the dotriacontane (C 32 ) was of reagent grade (Humphrey Chemical Co., CT, USA) recrystallized several times from petroleum ether. The SFO was analyzed for triacylglycerols (TAG) by HPLC [10], while the CW and the C 32 were analyzed by capillary GC-MS as described previously [3]. The composition is reported as the mean 6 standard deviation of at least two independent determinations (n = 2).…”

Pre-nucleation Structuring of Triacylglycerols and Its Effect on the Activation Energy of Nucleation

“…For each crystallized blend the melting temperature at the peak (T M ′) was calculated with the equipment software using the first derivative of the heat flux 6 . With the T M ′ values, the equilibrium melting temperature (T M°) for TP and TS in the blends was determined following the procedure of Hoffman and Weeks 7 , as described by Perez-Martinez et al 8 and ToroVazquez et al 9 . Based on the T M°v alues, crystallization temperatures (T Cr ) were selected in such a way to obtain similar supercooling conditions for all TP and TS blends investigated.…”

Impact of Frying on Fatty Acid Profile and Rheological Behaviour of Some Vegetable Oils

“…In these systems the molecular relationships occurring among TAGs families determine the thermodynamic conditions (i.e., supercooling and supersaturation) that drive the formation of a solid in a liquid phase and the phase behavior of the solid phase. The resulting three-dimensional TAGs crystal network and the phase behavior of TAGs are major factors determining the physical and functional properties (i.e., rheology, liquid phase entrapment, mouth feel, appearance and spreadability) in products such as margarine, butter, confectionary coatings and fillings [12]. Additionally, crystallization conditions such as cooling rate and thermal history (i.e., crystallization temperature and tempering process) have significant effects on the kinetics and physical properties of the crystallized systems.…”