Cereal Chem. 71:439-443   |  VIEW ARTICLE


Bound Free Fatty Acids in Glucoamylase-Digested Starches of Corn and Sweetpotato.

K. Kitahara, T. Suganuma, and T. Nagahama. Copyright 1994 by the American Association of Cereal Chemists, Inc. 

The raw starches from corn and sweetpotato were digested by glucoamylase and lipids remaining in the residual starch granules, especially free fatty acids (FFA), were investigated. FFA were determined by high- performance liquid chromatography after fluorescence labeling of the FFA. This method has enabled the determination of the FFA contents with samples of 20-100 mg without any procedures for concentration. The total FFA content (18.41 micromol/g of corn starch) was much larger than that (1.07 micromol/g of sweetpotato starch), which agreed with those reported previously. At the initial stage of digestion, the FFA in both starches were rapidly released. During the later stages, linoleic acid in corn starch decreased in proportion to the extent of the digestion, whereas all FFA in sweetpotato were hardly released. Gel- permeation chromatography analysis of both starches showed no significant difference in the mode of enzyme action on the starch components. On the other hand, observation by scanning electron microscopy of the residual starches revealed differences in their appearances, suggesting that the manner in which they are digested is different.