Quantitative and qualitative studies on grain sorghum for traditional beer (dolo) production in Burkina Faso.
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2012
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Abstract
In the Central Plateau of Burkina Faso, grain sorghum [Sorghum bicolor (L.) Moench] is the major cereal crop used to produce the traditional beer commonly called dolo. Improvement of the dolo chain supply that requires quantity and quality grain for dolo production to improve the supply chain constitutes a big challenge for processors and police-makers. To that end, studies were conducted (1) to determine the best cropping practice to optimize grain yields and grain quality for IRAT9 and Framida (two red grain sorghum varieties) for dolo production, through experiments combining water management techniques and fertilizer treatments and conducted from 2003 to 2005, (2) to evaluate sorghum malt and dolo quality criteria and parameters affecting quality and (3) to assess costs and profits of malt and traditional beer (dolo) production through surveys conducted from December 2006 through January 2007.
Results indicated that combination of water management techniques and fertilizer treatments largely influenced grain yield production and grain quality of the two red grain sorghum varieties. The best cropping system to optimize grain yield of Framida and IRAT9 was the use of tied-ridges and application of microdose with additional phosphorus and nitrogen. Tie-ridging technique produced the highest yield benefit of 241 kg ha-1 for Framida and 395 kg ha-1. Microdose with additional phosphorus and nitrogen produced the highest grain yield increases from 420 to 756 kg ha-1 for Framida and from 812 to 1346 kg ha-1 for IRAT9. Previous studies suggested a diastatic power of at least 70 mg of maltose equivalent per g of dry malt weight per minute for commercially acceptable sorghum malt in Burkina Faso, though the diastatic power of grain sorghum malt produced under traditional conditions was found to be 53.13 mg of maltose equivalent per g of dry malt weight per minute. Results from these studies indicate that for Framida the combination of water management techniques such as scarifying, tie-ridging, manual zai, mechanized zai or dry soil tillage with application of microdose + additional 20 kg P ha-1 and 30 kg N ha-1
produced a sorghum malt with higher diastatic power than the commercially acceptable one (Table 4.4) . For IRAT9, this targeted dp is only achieved in an agronomic practice combining scarifying and microdose + additional 20 kg P ha-1 and 30 kg N ha-1 (Table 4.5). Production of sorghum grain and malt with the needed characteristics for high dolo quality would be the use of water management techniques that sufficiently improve soil water conditions in combination with a microdose application with additional phosphorus and nitrogen to provide sufficient nutrients and particularly nitrogen to the crop.
The malt and traditional beer (dolo) quality assessment study indicated that the major quality criteria for malt quality assessment were perceived to be taste (82% of respondents) and presence/absence of roots in the malt (76%). Taste (82%), alcohol content (73%) and wort sufficiently cooked (63%) were perceived as major criteria for the dolo quality assessment. The major parameters affecting malt quality were perceived to be malt production period (100% of respondents), proportions of grain and the amount of water entering malting (100%), presence of pesticide residues in the malting grains (62%) and age of grain (64%). Processing method (100%), yeast source (100%), proportions of the components (crushed grain, water, mucilage, yeast) entering dolo production (97%), malt quality (97%), wort temperature at time of inoculation (96%), amount of energy available for cooking wort and sediment boiling time (92%), quality of mucilage (78%), malt with non-sweet taste (75%), presence/absence of roots in the malt (73%) and ease of filtering crushed malt (64%) were perceived as major parameters affecting the dolo quality.
The economic study showed differences in costs, sales and profits in the dolo chain from one group of members to another and from one category to another within each group. The study also indicated that, though equipment and raw materials were readily available throughout the year, their high cost limited accessibility and acquisition. Actions must be undertaken by policy-makers and developers to make credit available for farmers to produce quality sorghum grain and women processors to purchase equipment needed for malt and dolo processing, conservation and distribution, thus increasing profits. Other
important aspects to consider when designing programs to improve the dolo supply chain were the organization of malt and dolo production and marketing systems and suitable training programs to the benefit of all members to improve production skills and increase profit per unit cost in all dolo activities. Results from this study will help in the improvement of the dolo supply chain in Burkina Faso by providing more reliable information for (1) development of best cropping practices to improve grain quality, and providing better selection criteria for sorghum breeding programs, (2) development of training programs for efficient dolo brewing processes and (3) development of training programs to improve marketing systems and skills for chain members. It is expected that results from this study would further help increase the economic potential of sorghum in Burkina Faso and neighboring countries since a commercialized traditional product has a greater chance of being popular and culturally acceptable than an exotic or novel product.
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Ph.D. University of KwaZulu-Natal, Pietermaritzburg 2012.