The action of three technical mashing enzymes (hitempase 2XL, bioglucanase-TX and brewers protease) on yields of extract and free amino nitrogen (FAN) of the worts of mashes of unmalted and malted Madjeru sorghum was modeled and analyzed using the response surface methodology. The analysis showed that increasing amounts of hitempase 2XL considerably increased yields of extract during mashing of unmaltedMadjeru sorghum grist. The use of bioglucanase-TX was not indispensable, while Brewers’ protease contributed very little. Increasing amounts of hitempase contributed approximately 45% of the free amino nitrogen, while Brewers’ protease influence amounted to not more than 15%. Bioglucanase’s action was globally nil. Addition of the three enzymes into malted Madjeru sorghum mashes had no significant effect on the yields of extracts and FAN, but the milling operation singularly liberated more than 50% of FAN for both mash types. Optimization of the concerted actions of the three enzymes for extract yield for unmalted Madjeru sorghum mash gave a combination of (1960.5 U; 132.61 BGU and 28.86 mg) for hitempase, bioglucanase and brewers protease respectively). This gave a maximal extract yield of 16.55 °P. This combination was: 2610 U; 0 BGU and 40.44 mg for malted Madjeru sorghum mash, giving a maximal extract yield of 16.35 °P. Optimization for free amino nitrogen for unmalted Madjerusorghum mash gave a combination of: 3000 U; 0 BGU and 100 mg for hitempase, bioglucanase and brewers protease respectively). This gave maximal FAN of 93.55 mg/L. The combination was: 3000 U; 0 BGU and 100 mg for malted Madjeru sorghum mash, giving a maximal FAN of 144.48 mg/L.
Key words: Modeling, technical mashing enzymes, yields of extract, free-amino-nitrogen, Madjeru, optimization.
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