Isothermal and non-isothermal crystallization in amorphous sucrose and lactose at low moisture contents

X-ray diffraction analysis of lactose crystallization in freeze-dried lactose–whey protein systems

“…However, an increase in average molecular weight in a system might cause an increase in T g (Slade & Levine, 1991). According to previous reports Kedward et al, 2000;Ibach & Kind, 2007;Silalai & Roos, 2010), the phase separation could be found in lactose-protein systems and therefore they had almost composition independent T g with T g values of systems being mostly dependent on amorphous lactose (Fig. 4 A).…”

“…1). Systems with 70:30 (b 0.65 a w ) and 50:50 of lactose: WPI ratios (b0.76 a w ) could use water sorption data over a wider a w range Kedward, MacNaughtan, & Mitchell, 2000;Potes et al, 2012;Timmermann et al, 2001). As the wider water activity ranges were used in GAB model, the better fitting results would be achieved (Timmermann et al, 2001).…”

Differences in the physical state and thermal behavior of spray-dried and freeze-dried lactose and lactose/protein mixtures

“…Time-dependent lactose crystallization was observed from the loss of sorbed water (Jouppila & Roos, 1994a;Kedward et al, 2000;Vuataz, 1988). Lactose crystallization occurred in spray-dried and freeze-dried materials at RVP !…”

“…Crystallization occurs time dependently when water content or temperature exceed a critical value (Roos, 1995). A number of researchers have investigated lactose crystallization occurring in dairy powders during water sorption in storage (Jouppila, Kansikas, & Roos, 1997;Jouppila & Roos, 1994a, 1994bKedward, MacNaughtan, & Mitchell, 2000;Lai & Schmidt, 1990;Vuataz, 1988). Lai and Schmidt (1990) reported that amorphous lactose in skim milk powder crystallized and released water at 54% RH at 20 -C. Jouppila and Roos (1994b) observed that freeze-dried lactose and lactose in milk powders crystallized at RH > 40% at 24 -C. Other researchers (Lai & Schmidt, 1990;Roetman, 1979;Saito, 1985;Saltmarch & Labuza, 1980) also observed the appearance of lactose crystals in dairy powders by SEM.…”

Assessing the rate of solid-phase crystallization for lactose: The effect of the difference between material and glass-transition temperatures

“…It has been used as a correlation for fitting data from isothermal crystallization experiments, and the equation does not explicitly account for the effect of temperature. An attempt by Kedward, MacNaughtan, and Mitchell (2000) to include temperature into the equation, assuming a linear relationship between rate of crystallization and temperature, was successful for sucrose but failed Table 1 Values of k and n for the Avrami equation using XRD measurements at 20.9°of lactose at different conditions (Haque & Roos, 2005) for lactose, with the failure being attributed to the multiple crystal forms for lactose compared with the single crystal form for sucrose. The applicability of the Avrami equation has also been tested by Roos and Karel (1992) by measuring the crystallization rate of amorphous lactose using XRD for a diffraction angle of 20.9°, which is one of the characteristic angles for both alpha and beta forms, and the Avrami equation did not fit the results well.…”