| Abstract: | The objective of this research was to investigate the fermentation performance of waxy grain sorghum for ethanol production. Twenty‐five waxy grain sorghum varieties were evaluated with a laboratory dry‐grind procedure. Total starch and amylose contents were measured following colorimetric procedures. Total starch and amylose contents ranged from 65.4 to 76.3% and from 5.5 to 7.3%, respectively. Fermentation efficiencies were in the range of 86.0–92.2%, corresponding to ethanol yields of 2.61–3.03 gallons/bushel. The advantages of using waxy sorghums for ethanol production include easier gelatinization and low viscosity during liquefaction, higher starch and protein digestibility, higher free amino nitrogen (FAN) content, and shorter fermentation times. The results showed a strong linear relationship between FAN content and fermentation rate. Fermentation rate increased as FAN content increased, especially during the first 30 hr of fermentation (R2 = 0.90). Total starch content in distillers dried grains with solubles (DDGS) was less than 1% for all waxy varieties. |
