Arellano María Paz, Aguilera José Miguel, Bouchon Pedro
Departamento de Ingeniería Química y Bioprocesos, Escuela de Ingeniería, Pontificia Universidad Católica de Chile, Santiago, Chile.
Carbohydr Res. 2004 Nov 15;339(16):2721-30. doi: 10.1016/j.carres.2004.09.009.
Polarised light microscopy was employed non-invasively to monitor lactose crystallisation from non-seeded supersaturated solutions in real time. Images were continuously recorded, processed and characterised by image analysis, and the results were compared with those obtained by refractometry. Three crystallisation temperatures (10, 20 and 30 degrees C) and three different levels of initial relative supersaturation (C/C(s)=1.95; 2.34; 3.15) were investigated. Induction times using the imaging technique proved to be substantially lower than those determined using refractive index. Lactose crystals were isolated digitally to determine geometrical parameters of interest, such as perimeter, diameter, area, roundness and Feret mean, and to derive crystal growth rates. Mean growth rates obtained for single crystals were fitted to a combined mass transfer model (R(2)=0.9766). The model allowed the effects of temperature and supersaturation on crystallisation rate to be clearly identified. It also suggested that, in this set of experiments, surface integration seemed to be the rate controlling step. It is believed that a similar experimental set-up could be implemented in a real food system to characterise a particular process where crystallisation control is of interest and where traditional techniques are difficult to implement.
采用偏振光显微镜对非接种过饱和溶液中乳糖的结晶过程进行非侵入性实时监测。通过图像分析对图像进行连续记录、处理和表征，并将结果与折射法获得的结果进行比较。研究了三个结晶温度（10、20和30摄氏度）和三个不同水平的初始相对过饱和度（C/C(s)=1.95；2.34；3.15）。结果表明，使用成像技术测得的诱导时间明显低于使用折射率测定的诱导时间。通过数字方式分离乳糖晶体，以确定感兴趣的几何参数，如周长、直径、面积、圆度和费雷特均值，并推导晶体生长速率。将单晶获得的平均生长速率拟合到一个联合传质模型（R(2)=0.9766）。该模型能够清晰地识别温度和过饱和度对结晶速率的影响。它还表明，在这组实验中，表面整合似乎是速率控制步骤。据信，类似的实验装置可以在实际食品系统中实施，以表征结晶控制很重要且传统技术难以实施的特定过程。
