Deep-freezing of potato starch

Samples of oven-dried, air-dried, and moisturised potato starch (5, 13, and 24% w/w moisture content, respectively) were frozen in liquid nitrogen. Sa mples after thawing were studied by means of cross-polarised light beam mic roscope (CLBM), Fourier Transformation Infrared Spectroscope (FT-IR), powde r X-ray diffractometer, and non-contact Atomic Force Microscope (nc-AFM). R apid deep-freezing followed by thawing produced changes on the granule surf ace. They were accompanied by internal alteration manifested by FT-IR spect ra and powder X-ray diffractograms. The results depended on the water conte nt in the sample. Deep-freezing of moistened starch resulted in increased c rystallinity of granules. It had minor effect on the granule aqueous solubi lity and characteristics of gelation. (C) 2000 Elsevier Science B.V. All ri ghts reserved.