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Starch characterization and ethanol production of duckweed and corn kernel

Lee, Chang Joo, Yangcheng, Hanyu, Cheng, Jay J., Jane, Jay‐lin
Die Stärke = 2016 v.68 no.3-4 pp. 348-354
amylopectin, amylose, chemical structure, corn, corn starch, digestibility, ethanol production, physical properties, resistant starch, retrogradation, seeds, starch granules
The objectives of this study were to characterize the chemical structure, physical properties, enzyme digestibility, and ethanol production of duckweed starch and compare them with that of corn starch (B73). Duckweed consisted of 23.3% starch (dry basis, db), which was less than B73 corn kernels (66.5%). The morphology of duckweed starch granules displayed disk/dome shapes with one side of the granule flat and diameters of 4–9 µm. Duckweed starch displayed a B‐type polymorph, having an average amylopectin branch‐chain length of DP 26.5, and 35.7% amylose; both were larger than corn starch counterparts (DP 21.3 and 31.0%, respectively). Cooked duckweed starch showed higher resistant‐starch content (14.1%) and a greater percentage of retrogradation after 7‐day storage (57.5%) than the cooked B73 corn starch counterparts (8.7 and 49.6%, respectively). Duckweed plant produced a smaller ethanol‐yield (12.0 g/100 g plant, db) but a greater ethanol‐conversion efficiency (90.8%) than the B73 corn kernels (33.7 g/100 g kernels and 89.4%, respectively).