Optimization of Red Sorghum (Sorghum bicolor (L.) Moench) Malt Mashing Using Response Surface Methodology

Abstract

The Response Surface Methodology (RSM) was used to optimize the Released Glucose Equivalent during red sorghum malt mashing. Three parameters were tested: the β-amylase (EC 3.2.1.2) temperature level (min value = 62°C and max value = 63°C, TB), the α-amylase (EC 3.2.1.1) temperature level (min value = 72.5 and max value = 77.5°C, TA) and the duration of each stage (min value 15 min and max value 22.5 min, D). The optimal condition obtained during this study (TA = 79°C, TB = 63°C, and D = 18 min) would make it possible to obtain a wort of around 13° Plato. The Analysis of Variance shows that TB and D do not have a significant effect on Released Glucose Equivalent during mashing. This is probably due to the fact that in addition to the very low activity of β-amylase in sorghum malt, the starching temperature of sorghum starch is high and β-amylase is sensitive to heat. Therefore, this enzyme will be lost in larger quantities during mashing than α-amylase. However, the model obtained shows that the β-amylase Temperature (TB) can explain the release of simple sugars despite the fact that its effect is not statistically significant at the 0.1 threshold in the sense that the lack of adjustment of the model obtained is not significant at the same threshold. On the other hand, the temperature of α-amylase and the square of the duration significantly affect the release of simple sugars during mashing. The proposed model of the released Glucose Equivalent expressed as g of Glucose Equivalent per 100 g of red sorghum malt (GE) as affected by the β-amylase Temperature (TB), the α-Amylase Temperature level (TA), and the duration of each stage (D) obtained using RSM has presented a significant goodness of fit.