Comparison of rheological and colorimetric measurements to determine α-amylase activity for malt used for the beverage Bozo

Abstract

In the current study, rheological and colorimetric methods were compared for determination of α-amylase activity of grain malt, used for Kyrgyz traditional fermented beverage Bozo. The highest α-amylase activity determined by colorimetric method was found in barley malt (32.83 A), followed by wheat (32.09 A), and was lowest in millet malt (10.82 A) and maize malt (10.76 A). Rheological parameters of millet porridge without and with malt were studied. The liquefaction effect of millet porridge after addition of malt was determined with rotational and oscillatory measurements. Results from statistical analysis (partial least squares regression) revealed that oscillatory rheological parameters (yield stress τ, deformation γ, and storage modulus G′) could be an effective indicator to predict the α-amylase activity of the investigated malt with R2 = 0.9572. Consequently, rheological oscillatory measurements were recommended as an alternative tool to determine α-amylase activity of grain malt.