Sorghum in Fermentation: New Insights into Genetics, Grain Traits, and Microbial Interactions from Baijiu to African Traditional Beers
Sorghum (Sorghum bicolor) has long played a central role in the production of fermented beverages across continents, from West African dolo and pito to Chinese baijiu and emerging gluten-free craft beers in the West. A wave of recent research is shedding light on how sorghum’s grain properties, microbial interactions during fermentation, and genetic diversity influence the quality and sustainability of these beverages.
Microbial and Metabolic Interactions in Baijiu Fermentation
A study by Liu et al. (2023) used metagenomics, metaproteomics, and metabolomics to investigate the fermentation of strong-flavor baijiu with four different sorghum varieties. The researchers found that sorghum variety had a pronounced effect on microbial diversity and metabolic outcomes, particularly within the first 21 days of fermentation. Glutinous varieties such as Luzhouhong yielded the most desirable sensory profiles, linked to distinct microbial communities and volatile compound profiles. The study also emphasized the dominant role of bacteria, especially Lactobacillus, in shaping fermentation outcomes. These bacterial communities influenced amino acid and carbohydrate metabolism, key factors in determining flavor quality and aroma.
These findings align with a comprehensive review by Zhao et al. (2024), which outlines how grain traits like starch, protein, tannins, and fats significantly impact baijiu quality. The review underscores the importance of understanding how these components influence microbial activity and fermentation chemistry, providing a roadmap for improving sorghum selection and fermentation practices.
Genetic Signatures of Liquor-Making Sorghum
In parallel with these biochemical studies, Zhang et al. (2022) conducted a genome-wide association study of 244 Chinese sorghum accessions, identifying three distinct genetic subpopulations: Northern, Southern, and Chishui groups. These groups followed clear geographic patterns and showed selection signatures associated with traits valuable for baijiu production, including grain pericarp strength and inflorescence architecture. Importantly, the study showed that pericarp strength, more than grain size, was key to withstanding repeated cooking cycles during fermentation. These results offer breeders specific genetic targets for improving sorghum’s brewing suitability and contribute to a deeper understanding of the crop’s domestication history in China.
Sorghum in African Traditional Brewing and Sustainable Development
Across sub-Saharan Africa, sorghum remains essential in traditional beers such as dolo and pito. Sawadogo-Lingani et al. (2021) reviewed the production processes and microbiology of these spontaneously fermented beverages, which support both nutrition and livelihoods. The beers rely on lactic acid bacteria (LAB) and wild yeasts like Saccharomyces cerevisiae, with strain-level biodiversity playing a key role in fermentation dynamics. Despite their cultural and economic importance, traditional sorghum beers face challenges related to raw material quality, product consistency, environmental impact, and shelf life. The authors recommend interventions including improved sorghum varieties, better raw material storage, use of defined starter cultures, improved cookstoves, quality standards, and valorization of brewing by-products. These steps could enhance sustainability and scale production without compromising traditional practices.
Toward Industrial and Functional Sorghum Beverages
Growing demand for gluten-free and health-promoting beverages has led researchers to explore sorghum’s potential for modern brewing. Disharoon et al. (2020) evaluated 42 diverse sorghum accessions for amylase activity, grain color, and tannin content. They identified several lines with high alpha-amylase content and revealed genetic resources that could support improved malting efficiency. Their findings also point to associations between grain color and enzyme activity, providing a foundation for mapping and selecting traits related to fermentation efficiency.
Meanwhile, Garzón and Drago (2018) assessed 24 sorghum hybrids for both brewing performance and bio-functional properties. White sorghum hybrids tended to have higher diastatic power and beta-amylase activity, making them more suitable for brewing. Red sorghum hybrids, by contrast, had higher levels of GABA, phenolics, and antioxidant capacity, giving them promise as sources for functional beverages. The authors demonstrated that these properties could be predicted from grain composition, allowing for targeted selection based on end-use goals.
Implications for Sorghum Breeding and Genetic Improvement
The research highlighted here presents important opportunities for sorghum breeders. Fermentation-related traits such as diastatic power, amylase activity, pericarp strength, and volatile compound production can now be linked to measurable grain properties and specific genetic markers. These traits are ready to be incorporated into marker-assisted selection programs, enabling the development of varieties optimized for brewing and functional beverage production. Furthermore, the identification of selective sweeps and candidate genes for brewing quality traits opens the door to precision breeding of sorghum tailored to industrial or artisanal fermentation processes.
The continued exploration of underutilized landraces and hybrids also holds promise. These genetic resources may contain unique combinations of traits that support microbial resilience, enhance flavor diversity, or contribute to bio-functional properties of beverages. For researchers and breeders working to expand sorghum’s role as a sustainable, value-added crop, these findings provide a clear path forward: evaluate fermentation-relevant phenotypes across diverse germplasm, apply modern breeding tools to identify and propagate useful variation, and align breeding priorities with the needs of beverage producers and consumers alike.
References
Disharoon, A, Boyles, R, Jordan, K, Kresovich, S. Exploring diverse sorghum (Sorghum bicolor (L.) Moench) accessions for malt amylase activity. J. Inst. Brew. 2020 Dec 17; 127: 5–12. doi.org/10.1002/jib.628. Read more
Garzón AG, Drago SR. Aptitude of sorghum (Sorghum bicolor (L) Moench) hybrids for brewery or bio-functional malted beverages. J Food Biochem. 2018 Sept 27; 42:e12692. doi.org/10.1111/jfbc.12692. Read more
Liu MK, Tang YM, Liu CY, Tian XH, Zhang JW, Fan XL, Jiang KF, Ni XL, Zhang XY. Variation in microbiological heterogeneity in Chinese strong-flavor Baijiu fermentation for four representative varieties of sorghum. Int J Food Microbiol. 2023 Jul 16;397:110212. doi: 10.1016/j.ijfoodmicro.2023.110212. Epub 2023 Apr 14. PMID: 37084618. Read more
Sawadogo-Lingani H, Owusu-Kwarteng J, Glover R, Diawara B, Jakobsen M, Jespersen L. Sustainable Production of African Traditional Beers With Focus on Dolo, a West African Sorghum-Based Alcoholic Beverage. Front. Sustain. Food Syst. 2021 May 10; 5. doi:10.3389/fsufs.2021.672410. Read more
Zhang L, Ding Y, Xu J, Gao X, Cao N, Li K, Feng Z, Cheng B, Zhou L, Ren M, Lu X, Bao Z, Tao Y, Xin Z, Zou G. Selection Signatures in Chinese Sorghum Reveals Its Unique Liquor-Making Properties. Front Plant Sci. 2022 Jun 9;13:923734. PMID: 35755652. doi: 10.3389/fpls.2022.923734. Read more
Zhao W, Liu Y, Zhou K, Kehu Li, Shen J. How sorghum grain composition affects the quality of Chinese Baijiu – A comprehensive review. J. Food Compos. Anal. 2024 July 9; 134: 106512. doi.org/10.1016/j.jfca.2024.106512. Read more
