The alkali‐catalyzed depolymerization of amyloses in relation to iodine‐complexing properties

Abstract

When hydrolyzed in random fashion by acid or by a-amylase, amylose gradually loses the capacity to stain with iodine. As the degradation advances, the hyperchromic effect exhibited by the absorption spectra of the iodine complex is accompanied by a hypsochromic shift.l A quantitative measure of the specific absorption coefficient of the complex is provided by the peak value (P.V.), which is defined2 as the absorbance of a lo-% solution of polysaccharide in a standard iodine-iodide medium measured a t the wavelength of peak absorption, A

A Monte Carlo analysis of acid hydrolysis of glycosidic bonds in polysaccharides

“…Kainuma and French (1971) have also observed a certain resistance of amylose to hydrolysis, even if it gave initially an amorphous X-ray diffraction pattern. Ziderman and Weiss (1979), having hydrolyzed amylose for 18 hours, believe that it is the supramolecular organization of amylose structure that renders it stable to further major degradation in dilute acid. Indeed, amylose in solution undergoes retrogradation, a phenomenon caused by the alignment of linear chains which leads to hydrogen bond formation between chains until insoluble particles consisting of intertwined double helices are formed (Kennedy et al, 1987).…”

Using disaccharides as a kinetic model for alkaline degradation of celluloses and starches

“…The experimental conditions were identical to those used in our previous studies of amylose2 and hydroamylose. 6 Two rate constants were calculated from the measured data, as previously described2: k l is the coefficient for glucosidic scission and k 2 for the stopping reaction.…”