Cereal Chem 69:654-658 | VIEW
Swelling and Gelatinization of Cereal Starches. III. Some Properties of Waxy and Normal Nonwaxy Barley Starches.
R. F. Tester and W. R. Morrison. Copyright 1992 by the American Association of Cereal Chemists, Inc.
Starches were isolated from 12 waxy and six nonwaxy genotypes of barley grown in adjacent field plots to minimize edaphic variation. Amylopectin (AP) in all of the starches appeared to be very similar in structure. For the colorimetric determination of amylose (AM), a revised calibration curve was necessary because barley AP gave a lower lambda max (529 nm) and absorbance with I2/KI reagent that AP from other cereal starches used previously. The waxy starches contained AM (less than 7.4%) and lipids (120-630 mg/100 g), giving an AM-lipid relationship (r = 0.990) different from that in the nonwaxy starches; the B-granules in the waxy starches had about half of the AM and lipids found in the A-granules. The fatty acid composition of the lipids in the waxy starches was much more saturated than in the nonwaxy starches, and it was negatively correlated with total lipid content. Starch granule swelling at 70 and 80 C, after gelatinization (disordering) of AP is complete, is a property of the whole AP molecule. Swelling factors for the AP fraction, over the range of 4-35 for all starches from the present and previous studies, were inversely correlated with lipid content (r = -0.918, n = 30).