Kinetic models for batch ethanol production from sweet sorghum juice under normal and high gravity fermentations: Logistic and modified Gompertz models

J Biotechnol. 2017 Feb 10;243:69-75. doi: 10.1016/j.jbiotec.2016.12.012. Epub 2016 Dec 14.


The aim of this study was to model batch ethanol production from sweet sorghum juice (SSJ), under normal gravity (NG, 160g/L of total sugar) and high gravity (HG, 240g/L of total sugar) conditions with and without nutrient supplementation (9g/L of yeast extract), by Saccharomyces cerevisiae NP 01. Growth and ethanol production increased with increasing initial sugar concentration, and the addition of yeast extract enhanced both cell growth and ethanol production. From the results, either logistic or a modified Gompertz equation could be used to describe yeast growth, depending on information required. Furthermore, the modified Gompertz model was suitable for modeling ethanol production. Both the models fitted the data very well with coefficients of determination exceeding 0.98. The results clearly showed that these models can be employed in the development of ethanol production processes using SSJ under both NG and HG conditions. The models were also shown to be applicable to other ethanol fermentation systems employing pure and mixed sugars as carbon sources.

Keywords: Batch ethanol fermentation; Logistic function and modified Gompertz models; Normal (NG) and high (HG) gravity; Saccharomyces cerevisiae; Sweet sorghum juice.

MeSH terms

  • Batch Cell Culture Techniques / methods*
  • Carbohydrate Metabolism
  • Carbohydrates / administration & dosage
  • Carbon / administration & dosage
  • Carbon / metabolism
  • Ethanol / metabolism*
  • Fermentation
  • Fruit and Vegetable Juices / microbiology
  • Hypergravity
  • Kinetics
  • Models, Chemical*
  • Plant Extracts / chemistry
  • Plant Extracts / metabolism*
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / metabolism
  • Sorghum / chemistry
  • Sorghum / metabolism*


  • Carbohydrates
  • Plant Extracts
  • Ethanol
  • Carbon