In situ observation of pressure-induced gelation of starches studied with FTIR in the diamond anvil cell

Pressure-induced gelation of six different starch types has been followed by Fouriertransform infrared (FTIR) spectroscopy. The diamond anvil cell allowed us to follow changes in situ at high pressure. Changes in the infrared spectrum due to conformational modifications and solvation changes in the starch granule were analysed. The spectra of these starches showed a similar behaviour at increasing pressure. Bands in the region 900¯1300 cm-1 increased in intensity and changed position at high pressure. A correlation was found between the stability and the structure of the different starch types. B-type starches tend to be more pressure resistant than A- and Ctype starches. In situ observation of the gelation was also performed with a microscope. At the pressure at which gelation occurred, a swelling of the starch granules was observed.