AFRICA GOES SORGHUM: CHALLENGES AND OPPORTUNITIES

Moses Musisi

w Breweries Ltd, PO Box 762, Jinja,

ABSTRACT Close Bar

w Sorghum was first domesticated in Africa and has therefore played an important role in the culture and economies of African Countries since time immemorial. There are a number of key advantages and opportunities for brewing with sorghum including availability, knowledge of the crop as it is an indigenous crop, low price per kilogram of extract, gluten free and good colloidal stability of clear sorghum . Key brewing challenges include low free amino nitrogen (FAN) in sorghum worts that pause serious fermentation challenges, high tannin levels that bind proteins and therefore reduce enzyme efficiency, low foam potential, lack of a husk and low β-amylase even when sorghum is malted. Key research opportunities are there in areas of improving breakdown of kafirin to increase FAN, increasing foam potential, developing varieties with low tannin levels while at the same time resistant to birds, ability to brew with high tannin sorghums and production of other forms of brewing raw materials from sorghum like maltose syrup and starch. Africa grew clear beer volumes on average of 7% between 2005 and 2007 compared to 12% of SABMiller Africa between 2008 and 2010.

ACKNOWLEDGMENTS

I would like to express my thanks to Nile Breweries Ltd, a subsidiary of SABMiller, for having been kind to me to allow me to use the valuable resources that necessitated me to write this w paper.

BACKGROUND Close Bar

w Clear beer brewing has traditionally been from barley malt as a principle source of extract world over and other sources of raw materials only used as adjuncts. Adjuncts have been used essentially to supplement on malt for various reasons ranging from taste to cost. Sorghum has been used for brewing beer in Africa for ages, mainly for producing opaque beer, whose volumes still dwarf clear beer in many parts of sub-saharan Africa (SABMiller plc, 2009). Brewing clear beer from sorghum was put on industrial platform by Nigeria in the 1980s after government legislation banning importation of barley malt.

In 2002, SABMiller in Uganda launched its first commercial brew made from raw sorghum and from that time brewing clear beer from sorghum has not scaled down but gone significantly up in various African countries in which it operates.

Table 1: Projected clear beer production in Africa (After Canadean, 2008; SABMiller plc, 2009). Year 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 SABMiller Sorghum Beer 341 682 787 758 828 954 1,097 1,262 1,451 1,669 1,919 Nigeria Clear Sorghum Beer 8,269 9,468 10,412 11,453 12,599 13,858 15,244 16,769 18,445 20,290 22,319 w Total Africa Sorghum 10,615 12,156 13,206 14,219 15,436 16,822 18,352 20,042 21,909 23,973 26,253

Total Clear Beer Africa 71,923 76,969 82,653 88,439 94,629 101,253 108,341 115,925 124,040 132,723 142,013 Close Bar

% Sorghum to Barley malt beer 15% 16% 16% 16% 16% 17% 17% 17% 18% 18% 18% w

Key Opportunities from Sorghum

1. Sorghum is indigenous from Africa. Sorghum also called by its scientific name of Sorghum bicolor is a grass that has its centre of origin in Africa (FAO, 1995a). Its success in

conquering marginal areas of land where there is little rainfall is because of its extensive w root system, its ability to thrive with less water than maize, which may be due to its ability to hold water in its foliage better than maize, its waxy coating on its leaves and stems which helps to keep water in the plant even in intense heat and its yields are not affected

by short periods of drought as severely as other crops such as maize because it develops Close Bar

its seed heads over longer periods of time therefore short periods of water stress do not w usually have the ability to prevent kernel development (New World Encyclopedia, 2009). It is a perennial grass, though it is treated as an annual crop and can be harvested many times during the year (FAO, 1995a). All those factors make sorghum have a competitive advantage over other cereals as a number one choice for brewers as a reliable source of extract. 2. Over 30% of world’s Sorghum production is from Africa. World annual sorghum production is over 60 million tonnes, of which Africa produces over 20 million tonnes (Taylor, n.d.). The high tonnage of sorghum produced from Africa means it is a raw material that is readily available in the region, which gives the brewing industry an opportunity to tap into the vast resource without excessive amount of investment necessary compared to a pioneer crop. 3. Sorghum beer tradition. Sorghum has been used to brew local beer in Africa for ages, so the taste and sound of a clear beer from sorghum is not foreign to the population.

This shows that opaque beer volumes are three times bigger than clear beer in those selected countries in Southern Africa w

Table 2: Sorghum production in Africa in 2008 (After FAOSTAT, 2010).

Rank Country Production MT Close Bar

1 Nigeria 9,318,000 w 2 Sudan 3,869,000 3 Ethiopia PDR 2,316,041 4 1,875,046 5 1,311,100 6 Mali 1,027,202 7 United Republic of Tanzania 900,000 F 8 Egypt 866,948 9 Chad 685,430 10 Cameroon 600,000 F 11 Uganda 477,000 12 South Africa 373,000 * 13 330,950 14 Eritrea 302,515 F

15 227,927 * w 16 210,298 * 17 Mozambique 204,986 * 18 Senegal 189,787 * Close Bar

Total 25,085,230 w *: Unofficial estimate F: FAO estimate Table 3: Clear beer volumes compared to Opaque Sorghum beer in a few selected countries (After SABMiller, 2009).

Country Clear Beer. '000 hl Opaque Sorghum beer. '000 hl

Malawi 250 1000 w

Zambia 520 1600 Close Bar

Botswana 500 1500 w

Zimbabwe 1000 2500

Total 2270 6600

4. Sorghum is gluten free. Beer made from sorghum can be taken by people who suffer from celiac disease. Gluten occurs naturally in barley, wheat, and rye (Wikihow, 2010) but is not present in Sorghum. While sorghum has been successfully used to replace malted barley in African countries such as Nigeria and Uganda, more recent interest in the area of gluten-free beer, has highlighted sorghum on the world-stage as a leading contender for the production of gluten-free (Kerry, n.d.). Anheuser-Busch is already marketing its gluten free beer Redbridge from sorghum syrup (Anheuser-Busch, 2010). Celiac disease affects 1% of the population (Marian et al., 2004).

5. Price of sorghum is low. Compared to other raw materials that are used to make beer, the w price of sorghum is low even on extract basis. Comparatively a kilogram of extract from barley malt is US$ 1.30 while that of sorghum is US$ 0.50 in Uganda for example. 6. Technological challenges are not insurmountable. The sorghum structure is very similar to that of maize except for its much smaller size and generally oval shape (Taylor, n.d.). For Close Bar example neither grain has a true hull (husk), unlike barley or rice. The absence of the husk w in sorghum grain was up until recently considered a major problem with regard to using sorghum on lauter tuns. The advent of mash filters has broken this technological barrier. Modern mash filters have comparatively good extract recovery. 7. Diversification into secondary products. Sorghum can still be used to produce syrups, powder or even pure starch. These can be used as raw materials in the brewhouse. Sorghum syrups can effectively be used to increase brewhouse capacity. 8. Sorghum has low fat compared to maize. While sorghum has a close structure similar to maize, it has much less fat content compared to maize, this therefore lowers the rancid potential of beer (Taylor, n.d.). Maize can only be used if it is further processed into grits where the germ has been removed or if it is further processed into pure starch. 9. Sorghum beer has very good colloidal stability. Compared to malt or wheat beers, sorghum clear beer has better colloidal stability (Armad et al., 1998). This is due to polyphenolic compounds that have beneficial “functional” anti-oxidant properties. Brewing experience at SABMiller shows that beers made out of sorghum not only have longer shelf lives based on colloidal stability but also organoleptically. w

Key Challenges of the Sorghum Industry

1. Decision to brew with malted sorghum or raw sorghum is a challenge as each has its cons Close Bar

and pros. w 2. Brewing challenges: a. One of the major challenges of brewing with raw sorghum is that of very low free amino nitrogen (FAN) (Chisala et al., 2008). Several studies have shown that the levels of FAN in sorghum grain wort mashed with commercial enzymes are considerably lower than those obtained with sorghum and barley malt. The low levels of FAN attained when using exogenous proteolytic enzymes can be attributed primarily to the factors that contribute to the low digestibility of the kafirin fraction of sorghum protein, which accounts for around 70% of total grain protein. Use of reducing agents like 2-mercaptoethanol, sodium bisulphate and ascorbic acid, improve sorghum protein hydrolysis (Chisala et al., 2008). Low FAN leads to tailing fermentations and therefore low fermentation efficiency. b. Tannin levels in sorghum pause a challenge in that it binds with both the grain proteins w (Price et al., 1980) and the exogenous enzymes. Astringency of sorghum increases cost of enzymes and reduces the nutritional value of the grain in case of enzymes of the digestive tract (Armad et al., 1998). The high levels of tannins in some varieties of sorghum mean that they can’t be used for brewing as conversion is difficult with Close Bar commercial enzymes. This causes high brewhouse losses and a high cost of w enzymes. This means that a large quantity of the sorghum produced in Africa can’t be used for clear beer production in spite of its availability. c. Poor foam potential of clear sorghum beers (Kerry n.d.). d. The absence of a hull (husk) in sorghum grain was until recently considered as major technological problem. e. Even when sorghum is malted, it contains low levels of of β-amylase (Taylor, n.d.). f. Fast decrease in pH during fermentation leads to sour acidic taste. g. Poor flocculation of yeast at end of storage. h. Depending on the variety of sorghum, tartness can be quite high. 3. Agronomical: a. Low yields per acre. Average yields of sorghum in Africa remain below 1 tonne/ha (Taylor, n.d.), so the increase in quantity of sorghum has been due to increase in acreage and not yield per unit area. This means that there is little surplus sorghum on which processing industries can rely. b. Diseases like leaf diseases, smut and parasitic weeds like Striga.

c. Birds – they attack the varieties suitable for clear beer brewing. Quantitative w assessment done in Awash Basin in Ethiopia, indicated that the Red-billed Quelea (Quelea quelea) can be an important limiting factor in overall production of sorghum and that damage can be locally severe (Michael, 1980).

4. Social economic factors which include among others are: Close Bar a. Poor infrastructure in the marginal areas where sorghum is grown w b. Marketing and logistical issues c. Under developed agricultural practices coupled with lack of economical irrigation systems 5. Resistance and controversies associated to genetically modified foods and organisms slows down scientific research

Key Research Opportunities a. Development of enzyme systems that can increase hydrolysis of proteins in sorghum to yield more FAN than the current enzymes. It has been shown that sorghum contains as much total proteins as barley but the difference is the predominance of kafirin protein that doesn’t contain lysine and difficult to hydrolyse (Mugode et al., 2009; Taylor, n.d.). b. Development of high yielding varieties. Increase in sorghum production has been due to increase in acreage under cultivation. This strategy should change to increasing yield per area and not opening up new virgin land. c. Development of varieties that are resistant to various diseases. w d. Development of varieties that are not palatable to birds but retain brewing qualities e. How to unlock the kafirin protein matrix either with varieties that have less of the matrix or more efficient enzymes than what are currently on market

f. Given good colloidal stability, there is still room for more research in understanding the Close Bar

mechanisms that can lead to a beer with much longer shelf life than current clear beers. w g. Development of new yeast strains, that would produce a clean beer while getting good fermentability. Current yeast strains, struggle to ferment sorghum beer with low free amino nitrogen h. Longer shelf life for the traditional opaque beer from sorghum i. While high tannin levels prevent bird damage to red sorghum, they prevent those types of sorghum from being used to brew clear beer as these bind commercial enzymes making starch conversion difficult. Research into how to brew with high tannin sorghum, while at same time get those benefits that prevent bird damage is desirable. j. Research into production of syrups from red sorghum. This is high tannin sorghum that cannot be used in the brewhouse using conventional enzymes. If syrups are produced w from the cheap red sorghum that is less vulnerable to birds, then the cost of extract can be further reduced. k. Production of pre-gelatinised sorghum starch can cut costs off production in the brewhouse. Pre-gelatinised sorghum starch would convert for a much shortened time Close Bar therefore reducing brewhouse cycle time and cut on energy costs of boiling. w

CONCLUSIONS

While sorghum is Africa’s second most important cereal after maize and the world’s fifth largest most important cereal after wheat, maize, rice and barley, its full potential in terms of processing has not been realized. For Brewers in Africa, sorghum presents itself as a vast source of raw material that is cheap and readily available. Key challenges still remain like low FAN and high tannin levels but these should be looked at opportunities for research.

REFERENCES

Anheuser-Busch. (2010). Redbridge Beer Made with you in Mind. http://www.redbridgebeer.com/homePage.aspx. Retrieved December 15th, 2010. Armad, R., Anderson, H., Bardocz, S. & Serra F. (1998). Polyphenols in Food. Office for Official Publications of the European Communities, Brussels. Canadean. (2008). ICARP–International Centre for Alcohol Policies; NW, Washington. w http://www.icarp.org/LinkClick.aspx?fileticket=zcL0oIlydvE%3D&tabid=235. Retrieved December 16th, 2010.

Chisala, C. Ng’andwe, Alan, N. Hall & Taylor, J.R.N. (2008). Proteolysis of Sorghum Endosperm Close Bar Proteins when Mashing with Raw Grain Plus Exogenous Protease and Potassium w Metabisulphite. J. Inst. Brew.114(4), 343-348, 2008. Emmambux, M.N. and Taylor, J.R.N. (2003). Sorghum kafirin interaction with various phenolic compounds . Journal of the Science of Food and Agriculture in press. FAOSTAT. (2010). http://faostat.fao.org/site/339/default.aspx. Retrieved December 13, 2010. Food and Agricultural Organization (FAO) of the United Nations. (1995a). Sorghum and in human nutrition: Chapter 1: Introduction. FAO Corporate Document Repository. Retrieved December 07, 2010. Food and Agricultural Organization (FAO) of the United Nations. (1995a). Sorghum and millets in human nutrition: Chapter 4: Chemical composition and nutritive value FAO Corporate Document Repository. Retrieved December 07, 2010. Kerry (n.d.). High Adjunct Brewing. http://www.brewing-solutions.com/adjunct_process.php?action=details&id=13. Retrieved December 15th, 2010. w Marian, J. Rewers. (2004). Epidemiology of Celiac Disease: What Are the Prevalence, Incidence, and Progression of Celiac Disease? http://consensus.nih.gov/2004/2004CeliacDisease118Program.pdf#page=40. Retrieved December

15th, 2010. Close Bar w Michael, M. Jaegar., & William, A. Erickson. (1980). Levels of bird damage to sorghum in the Awash Basin of Ethiopia and the effects of the control of Quelea nesting colonies. Proceedings of the 9th Vertebrate Pest Conference. http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1036&context=vpc10. Retrieved December 15th, 2010. Mugode, L. (2009). Free Amino Nitrogen Improvement in Sorghum Malt Brewing. Unpublished Master’s Thesis, University of Pretoria, South Africa. http://upetd.up.ac.za/thesis/available/etd- 08162010-173519/unrestricted/dissertation.pdf. Retrieved December 15th, 2010. New World Encyclopedia. (2009)

http://www.newworldencyclopedia.org/entry/Sorghum. Retrieved December 09, 2010. w Price, M.L. & Butler, L.G. (1980). Tannins and Nutrition, Station Bulletin No. 72, Purdue University Agricultural Station, USA.

SABMiller plc. (2009). Quarterly divisional seminar series, Africa and Asia. 22 September 2009 Close Bar (London) and 23 September 2009 (New York) w http://www.sabmiller.com/files/presentations/2009/220909/220909_africaasia_quarterly_seminar.pdf. Retrieved December 15th, 2010. Taylor, J.R.N. (n.d.). Overview: Importance of Sorghum in Africa. http://www.afripro.org.uk/papers/paper01Taylor.pdf. Retrieved December 07, 2010. Wikihow. (2010). How to Homebrew Gluten Free Sorghum Beer. http://www.wikihow.com/Homebrew-Gluten-Free-Sorghum-Beer. Retrieved December 15th, 2010.

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