Degradation of Na amylose xanthate in dilute caustic soda solution during ripening

Na amylose xanthate was prepared from potato starch by xanthation of amylose in dilute NaOH solution. Pure xanthate was then isolated and viscometric and turbidimetric studies on its ripening characteristics were carried out for a period of about 200 hrs. Prolonged ripening in air degraded the amylose chain without formation of gel. To study the nature of ripening more precisely, it was carried out in an identical way under N2 and followed both viscometrically and turbidimetrically. The refractive‐index increment (dn/dc) of the xanthate solutions during ripening under both air and nitrogen was continuously measured so as to avoid any possible error in computing correct molecular weights during ripening. Light‐scattering molecular weights (M̄w) thus computed during the course of degradation of Na amylose xanthate extending for about 200 hr under both air and nitrogen were found to obey a first‐order rate equation, In (M0/Mt) = Kt where Mo is the initial molecular weight, Mt the molecular weight at time t of ripening, and K the rate constant of the degradation process.