The potential of sweet sorghum as a source of ethanol and protein

• Sweet sorghum has been evaluated in terms of energy and food security
• Ethanol productivity used as energy security indicator
• Grain nutritional characteristics used as food security indicator
• Ethanol was produced by simultaneous sugar extraction and fermentation
• Nutritional grain evaluation by employing biological tests with rats
• The Top 76-6 variety provided the best outcome

Sweet sorghum is a multipurpose crop with the potential to achieve sustainable biofuel production, human food and animal feed products. Six sweet sorghum varieties were sowed in the Guatemalan Pacific coastal plains for this study. Our goal was to determine which sweet sorghum variety had the combination of higher ethanol productivity from the stem's soluble sugar, and higher nutritional value from the grain. The Top 76-6 variety had the best combined outcome of, higher ethanol productivity and best grain protein quality. The stem and grain average yields obtained were 42.15 Mg of fresh stalk/ha and 2.36 Mg dry grain/ha, respectively. The average ethanol productivity was approximately 220 g ethanol per kg of original dry stem, equivalent to 2465 l of ethanol per ha. The grain had the lowest polyphenol levels and an adequate relative protein quality indicated by a 1.07 protein efficiency ratio value and an 83.2% protein digestibility.