Study on crystallization tendency of disaccharides by X-ray scattering

To see the structure of a material different techniques have been used over the years and X-ray diffraction, a nondestructive method, is one of them. For investigating biological sample, X-ray diffraction (which is based on scattering of X-rays) is gaining popularity because of its higher penetration depth compared to other methods. For its ability to detect in the order of the atomistic scale, wide angle X-ray scattering (WAXS) is used in the study. Two reducing sugars, cellobiose, and melibiose, were chosen for this study to investigate the effect of change of parameters (temperature, stored humidity) on their amorphous to crystalline transition. The powder cellobiose and melibiose samples were freeze-dried, re-humidified and crystallinity were measured by WAXS method. For crystallization of sugar, glass transition temperature (Tg) is the most important parameter as it is the threshold temperature for crystallization. Water content and stored temperature have an inverse relation for amorphous to crystalline transition. Based on this X-ray diffraction study, it was found that water component, storage time and temperature have an important effect on the crystallization of cellobiose and melibiose. Amorphous cellobiose needs sufficient temperature or water content to start crystallizing, whereas, the storage time is more vital than water component and temperature for crystallization of melibiose. Amorphous cellobiose became completely crystal when the stored humidity was more than 44% or the temperature was 86°C or higher but, amorphous melibiose did not crystallize, even when the temperature was 120°C. Melibiose had shown a slow but gradual transition from amorphous to crystal state whereas crystallization of cellobiose was an all-in all out way with fast crystallization rate. Though X-ray scattering is an indirect method, it is robust, powerful, and rapid and in general, obtained results are unambiguou