The Use of Response Surface Methodology to Optimise Malting Conditions of Proso Millet (Panicum miliaceum L.) as a Raw Material for Gluten-Free Foods

Abstract

Response surface methodology was used to investigate the influence of the three malting parameters, i.e. degree of steeping, germination time, and temperature on the quality of proso millet malt. Each predictor variable was tested at three levels. Germination times varied from 5, 6, and 7 days, degrees of steeping were 44, 48, and 52%, and germination temperatures were 16, 20, and 24°C. A set kilning temperature of 65°C was used for all malts. A series of malt quality parameters were investigated including extract, apparent attenuation limit, gelatinisation temperature, ␣-amylase activity, ␤-amylase activity, limit dextrinase activity, Kolbach index, ␣-amino nitrogen, viscosity, and colour. The optimal malting program was achieved after the fifth day of germination, 44% degree of steeping, and a 22°C steeping and germination temperature. The obtained values for the amylolytic and cytolytic attributes were 64.8% extract, 1.383 mPa × s viscosity, 76.0% apparent attenuation limit, 111 U /g ␣-amylase activity, and 102 U /g ␤-amylase activity.

Teff (Eragrostis tef) as a raw material for malting, brewing and manufacturing of gluten-free foods and beverages: a review

“…Presence of too little enzyme activities in the mash may lead to several undesirable consequences such as low extract, longer time to separate the wort, slow fermentation process, too little alcohol in the final product, microbiological instability, reduced filtration rate of the beer, and inferior flavour and stability of the beer. Zarnkow et al (2008) reported that teff malt has good level of enzyme activities though the recorded α-and β-amylase activities (75 and 213 U/g, respectively) are lower than those of barley malt 106 and 514 U/g, respectively (Phiaraise et al 2005). The levels of the enzyme activities of four different teff varieties reported by Zarnkow et al (2008) were enough to use them as suitable raw materials for malting.…”

“…Zarnkow et al (2008) reported that teff malt has good level of enzyme activities though the recorded α-and β-amylase activities (75 and 213 U/g, respectively) are lower than those of barley malt 106 and 514 U/g, respectively (Phiaraise et al 2005). The levels of the enzyme activities of four different teff varieties reported by Zarnkow et al (2008) were enough to use them as suitable raw materials for malting. However, the gelatinization temperature of teff (68-80°C) (Bultosa 2007) is too high for the amylolytic enzymes.…”

“…Thus, it may be useful to consider an adjunct mashing regimen for wort production. Research findings showed that the highest limit dextrinase value of teff malt (894 U/Kg) is twice the average limit dextrinase value of barley malt (400 U/Kg) (Zarnkow et al 2008).…”

“…Thus, it is a potential cereal for brewing process and can be used as a substitute for wheat flour in almost all its applications. Malting and brewing processes for teff have not been extensively investigated except for the study conducted by Zarnkow et al (2008) on the optimization of the malting conditions of teff (Fig. 5).…”

“…Based on the result of this study, they concluded that the optimal malt is obtained after 4 days of germination with 48 % degree of steeping, and a set temperature of 24°C for steeping and germination. Studies showed that like other cereals teff is predominantly starchy; the starch content and its malt quality are indicators of its suitability as raw material for brewing (Bultosa 2007;Zarnkow et al 2008). Protein content of teff is comparable to those of wheat and barley, and it is nutritionally superior because of its high levels of amino acid profile (FAO 1970;National Research Council 1996), making it an excellent material for malting and brewing.…”