Optimization of fermentation parameters for cereal-porridge production using Response Surface Methodology (RSM)

The possibility of the production of ‘ogi’ (a Nigerian cereal-porridge) with optimum quality was investigated using the Response Surface Methodology (RSM). Grains of white maize (Zea mays) and sorghum (Sorghum bicolor) were used separately and in combination (1:1 w/w), as the substrates for fermentations for a duration of 48h at ambient conditions. The starter cultures used in the controlled experiment consisted of 2 strains of Lactobacillus fermentum and a yeast, Pichia kudriavzevii. The organoleptic assessment of the ‘ogi’ showed that there was significant difference observed between the ‘ogi’ from the different substrates, with the maize-sorghum blend substrate being the most acceptable. Response surface optimization analysis using Box Behnken design revealed that the most desirable (0.89 desirability) conditions for ‘ogi’ production that could yield the following responses: pH of 5, protein content of 2.28% with overall acceptability of 8.5 were: temperature of 28 °C, substrate concentration of 50%, inoculum concentration of 4.0%, at 10h of fermentation. Response Surface Methodology was efficient in optimizing major fermentation conditions for the production of ‘ogi’ of high desirability from maize-sorghum blend, with the predictive and experimental values being closely related. The conditions could be employed in pilot study and industrialization of ‘ogi’ production.