Nucleation and growth in sucrose solutions

Sugar crystallization in food products

“…The results of Van Hook and co-workers, as well as a number of Russian investigators, 73 indicate that the classic model of nucleation (Equation 8) describes the nature of the formation of sucrose crystals by a primary nucleation process at least qualitatively, 73 and that the mechanism is essentially a diffusion-controlled process. This contention is supported by the apparent activation energy for the nucleation process being approximately the same as that for the viscosity and diffusion of sucrose molecules as well as from the profound influence of the solution viscosity on the nucleation process.…”

“…In further experimental work, careful studies on the nucleating ability of various foreign substances added to supersaturated sucrose solutions, including mannite, lactose, glucose, fructose, tartaric acid, calcium carbonate, and lithium sulfate monohydrate crystals, resulted in no enhancement of nucleation. 73 That is, none of the above-mentioned substances in their pure state were capable of nucleating sucrose solutions from the metastable supersaturation zone. Van Hook's comments regarding nucleation of sucrose remain appropriate to this date: "These topicsthe structure of the crystal nucleus and heterogeneous nucleation of sucrose syrups -remain virtually untouched domains for both theoretical and practical investigation and are extremely promising since heterogeneous theory avoids most of the statistical difficulties encountered in homogeneous nucleation theory, and macroscopic concepts may be employed since the particles generally contain many, many crystals."…”

“…Van Hook's comments regarding nucleation of sucrose remain appropriate to this date: "These topicsthe structure of the crystal nucleus and heterogeneous nucleation of sucrose syrups -remain virtually untouched domains for both theoretical and practical investigation and are extremely promising since heterogeneous theory avoids most of the statistical difficulties encountered in homogeneous nucleation theory, and macroscopic concepts may be employed since the particles generally contain many, many crystals." 73 The induction time for the onset of nucleation of pure sucrose solutions has been correlated to supersaturation by a number of researchers. Kuijvenhoven 75 found the following relationship to apply T h = 170(S -I)-113 (14) over the supersaturation ratio (based on grams per 100 g water) range 1.1 < S < 1.6 for the spontaneous formation of sucrose conglomerates.…”

Metastable zone width for secondary nucleation and secondary nucleation inside the metastable zone

“…Additionally, the estimated ΔG c , 3D,Sec. , using equation (2), is 28.1 kJ/mol, which equals ≈ 2.5 times of the estimated ΔG c , 3D,Hom as predicted by Van Hook and Bruno [32]. However, their value was estimated for a range of temperatures from 298.15 K to 313.15 K, using Arrhenius plot, which may contain a pseudo kinetic order for the nucleation rate, and subsequently a questionable estimate of the activation free energy.…”

Temperature effects on growth and nucleation rates in mixed suspension crystallization

“…While it is true that the interrelation of the above factors is quite, ccniplcx, it is essential for proper crystal ii%er design and operation that studies be made concerning their effects on the crystal lization kinetics. One pertinent area that has been sorely neglected is that of the dependence of the kinetics on the temperature of opera tion (35). Most of the work done in this area has been that of the determination of the effect of temperature on the growth rate of single crystals when operating at a constant degree of supersaturation.…”