Gianfranco Mazzanti

Edible oil structures at low and intermediate concentrations. II. Ultra-small angle X-ray scattering of in situ tristearin solids in triolein

Ultra-small angle X-ray scattering has been used for the first time to elucidate, in situ, the aggregation structure of a model edible oil system. The three-dimensional nano- to micro-structure of tristearin solid particles in triolein solvent was investigated using 5, 10, 15, and 20% solids. Three different sample preparation procedures were investigated: two slow cooling rates of 0.5°/min, case 1 (22 days of storage at room temperature) and case 2 (no storage), and one fast cooling of 30°/min, case 3 (no storage). The length scale investigated, by using the Bonse-Hart camera at beamline ID-15D at the Advanced Photon Source, Argonne National Laboratory, covered the range from 300 A to 10 μm. The unified fit and the Guinier-Porod models in the Irena software were used to fit the data. The former was used to fit 3 structural levels. Level 1 structures showed that the primary scatterers were essentially 2-dimensional objects for the three cases. The scatterers possessed lateral dimensions between 1000 and 4...

Modeling of a two-regime crystallization in a multicomponent lipid system under shear flow

Abstract.The kinetics of phase transitions of milk fat triacylglycerols, as model multicomponent lipid systems, were studied under shear in a Couette cell at 17 °C, 17.5 °C and 20 °C under shear rates ranging from 0 to 2880s^-1 using synchrotron X-ray diffraction. Two-dimensional diffraction patterns were captured during the crystallization process. No effect of shear on onset time for phase α from the liquid was observed. Afterwards a two-regime crystallization process was observed. During the first regime, as observed in other systems, shear reduced the onset time of the phase transition from phase α to 2880s−. The model previously developed for palm oil (ODE model) worked well to describe this regime, confirming the general value of the proposed ODE model. However, the ODE model did not satisfactorily describe the second regime. We found that, as the system gets closer to equilibrium, the growth regime becomes controlled by diffusion, manifested by the kinetics following a

An in situ method for observing wax crystallization under pipe flow

\sqrt t

Modeling Phase Transitions During the Crystallization of a Multicomponent Fat Under Shear

dependence. This regime was found to be consistent with a mechanism combining step growth at a kink with progressive selection of the crystallizing moieties. This mechanism is in agreement with the displacement of the diffraction peak positions, which revealed how increased shear rate promotes the crystallization of the higher melting fraction affecting the composition of the crystallites.

Effect of minor components and temperature profiles on polymorphism in milk fat

Fluorescence recovery after photobleaching (FRAP) has been used to quantify Nile red diffusion through five different triglyceride crystal networks composed of pure peanut oil (PeO), pure chemically interesterified fully hydrogenated palm oil (IHPO), two blends of PeO and IHPO blended in different mass ratios (70:30 and 30:70%, w/w), and pure cocoa butter. Calculated components from FRAP experiments (effective diffusion coefficient (D(eff)) and mobile fraction (Mr)) were correlated with crystal network structural characteristics (crystalline mass fraction and permeability coefficient) and illustrated that D(eff) can be predicted using this tool. Higher-permeability coefficients found for higher fractal dimensions, lower volume fraction of solids, and larger average particle sizes were significantly correlated to higher D(eff).

NOVEL SHEAR-INDUCED PHASES IN COCOA BUTTER

We report on an x-ray diffraction investigation of the nucleation and growth of wax crystals and the evolution of the resulting wax-gel deposit in mixtures of paraffin wax and dodecane under pipe flow. This work is an in situ x-ray diffraction study of wax crystallization in oil-wax mixtures under flow and is completely noninvasive. This technique is shown to be consistent with other methods.