STARCH SOLUBILIZATION AND RETROGRADATION DURING PREPARATION OF TO (A FOOD GEL) FROM DIFFERENT SORGHUM CULTIVARS

Starch solubilization and retrogradation were studied during the prepa ration of a food gel called to. Ti, was prepared from flours of four s orghum cultivars with different endosperm textures. Flour and water sl urry (17% solids) at pH 8.6 was cooked for 5 min to yield a hot paste (fresh ta) or allowed to cool for 1 hr at 25 degrees C to yield a stif f gel, (aged to). Fresh and aged ta were dispersed in water at 25 degr ees C by blending and centrifuging. Soluble starch was extracted at 35 degrees C, and the apparent molecular weight was quantified by high-p erformance, size-exclusion chromatography. Amylose (AMY) and amylopect in (AMP) starch was only partially solubilized in fresh to. Aged to co ntained even less soluble starch. Although more soluble starch was obs erved in fresh IB prepared from sorghums with more corneous (hard) end osperm than floury (soft) endosperm, the resulting aged to contained s ignificantly less soluble starch. Increased firmness of aged to prepar ed from the more corneous sorghums corresponded to more starch retrogr adation as measured by loss of soluble starch. Higher molecular weight soluble AMY and AMP were observed in fresh to compared to aged to. Re trogradation of soluble AMY and AMP in fresh ta appears to be faster f or higher molecular weight than for lower molecular weight polymers.