Effects of the order of addition of reagents and catalyst on modification of maize starches.

The objective of this research was to determine if adding reactive reagents to starch granules before addition of alkali (TRF method) would produce products that are different than those obtained by adding alkali before addition of reagent. Normal (NMS) and waxy (WMS) maize starches were each reacted with acetic-adipic mixed anhydride (AAMA), phosphoryl chloride (POCl3), sodium trimetaphosphate (STMP), acetic anhydride (AA), succinic anhydride (SA), and octenylsuccinic anhydride (OSA). Almost no or no starch polymer molecule modification occurred when the TRF method and AAMA, AA, or POCl3 were used; less than half as much reaction when SA was the reagent used, and about the same amount of reaction when STMP or OSA were the reagents used (for different reasons). It was concluded that most AAMA, AA, SA, and POCl3 reacted with surface protein molecules when the TRF method was used and that OSA molecules were driven into the structured internal water of granules.