Pearl millet grain: A mini-review of the milling, fermentation and brewing of ontaku, a non-alcoholic traditional beverage in Namibia

Abstract

Pearl millet is a cereal that grows and produces grains in arid areas where other cereals may not survive. It has the potential to become a global food crop as the world experiences climate change. Pearl millet is a staple food for more than 60% of the Namibian human population. It is processed into flour, porridge and a daily-consumed fermented acidic beverage, known as ontaku or oshikundu. This drink comprises pearl millet meal, sorghum or pearl millet malt and water. Ontaku has a heterogeneous composition and a short shelf life, usually of less than a day at ambient conditions. Its brewing processes are various but all are not standardised. Freshest ontaku is non-alcoholic, but over time it can have an alcohol content of up to 1.6%. The quality and phenolic content of the malt and the composition of congeners and fermentation metabolites such as methanol and butyrate in ontaku have not been investigated. The production of ontaku with improved safety and of predictable, consistent and consumer-acceptable qualities requires the standardisation and control of ingredients and processing conditions. This contribution provides a mini-review on the malting, fermentation and milling processing steps and the underlying basic science involved in the production of the ingredients used in the brewing of ontaku. It also highlights gaps in knowledge to aid future research in the field of African traditional fermented cereal foods.

Keywords:

• pearl millet
• ontaku
• sorghum malt
• milling
• fermentation

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).