Cereal α-amylases—an overview

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.

Section: Amylolytic Specificationsmentioning

confidence: 49%

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

Zarnkow¹,

Kessler²,

Burberg³

et al. 2007

“…Based on the data presented in Fig. 2, the temperature optimum for proso millet malt α-amylase activity in starch was 50°C, which was only slightly different from barley, which was 55°C 28 .…”

Section: Resultsmentioning

confidence: 99%

Optimisation of the Mashing Procedure for 100% Malted Proso Millet (Panicum miliaceum L.) as a Raw Material for Gluten-free Beverages and Beers

Zarnkow

Kessler

Back

et al. 2010

J. Inst. Brew. 116(2), 141-150, 2010Proso millet is a gluten-free cereal and is therefore considered a suitable raw material for the manufacturing of foods and beverages for people suffering from celiac disease. The objective of this study was to develop an optimal mashing procedure for 100% proso millet malt with a specific emphasis on high amylolytic activity. Therefore, the influence of temperature and pH on the amylolytic enzyme activity during mashing was investigated. Size exclusion chromatography was used to extract different amylolytic enzyme fractions from proso millet malt. These enzymes were added into a pH-adjusted, cold water extract of proso millet malt and an isothermal mashing procedure was applied. The temperatures and pH optima for amylolytic enzyme activities were determined. The α-amylase enzyme showed highest activity at a temperature of 60°C and at pH 5.0, whereas the β-amylase activity was optimum at 40°C and pH 5.3. The limit dextrinase enzyme reached maximum activity at 50°C and pH 5.3. In the subsequent mashing regimen, the mash was separated and 40% was held for 10 min at 68°C to achieve gelatinisation. The next step in the mashing procedure was the mixture of the part mashes. The combined mash was then subjected to an infusion mashing regimen, taking the temperature optima of the various amylolytic enzymes into account. It was possible to obtain full saccharification of the wort with this mashing regimen. The analytical data obtained with the optimised proso millet mash were comparable to barley wort, which served as a control.

“…Rice is different from these cereals because it can germinate under anaerobic conditions due to the activity of α-amylase II-4 isoform 7 . The expressions of α-amylase and β-amylase enzyme have been investigated extensively elsewhere 12,15,17,27 , whilst the production of α-and β-amylase under the malting conditions of rice lacks published data. Therefore, in this paper, α-and β-amylase production, as function of steeping duration and germination temperature, was investigated for rice malt production.…”

Section: Introductionmentioning

confidence: 99%

The Influences of Steeping Duration and Temperature on the α- and β-Amylase Activities of Six Thai Rice Malt Cultivars (Oryza sativa L. Indica)

Usansa

Sompong

Wanapu

et al. 2009

A preliminary study of malting conditions for six Thai rice cultivars was conducted. Three non-glutinous rice cultivars (KDML105, PT60, and WR) and three glutinous rice cultivars (SPT, RD6, and KND) were selected. The steeping durations (24, 48, and 72 h) and temperatures (20, 25 and 30°C) were investigated for their effect on α-and β-amylase, the key enzymes for malt quality evaluation. During steeping, the production of both enzymes was lower than at the germination process. The longer the steeping duration, the lower the maximum β-amylase activity obtained. The contradictory effect was observed for α-amylase activity, near the end of the germination time. Additionally, temperature influenced the water absorption content as well as the amylolytic enzyme activity. Particularly at 30°C, the maximum β-amylase activity (6.7 unit/mg protein) was found in KND malt steeped for 24 h, and maximum α-amylase activity (20 unit/mg protein) was found in PT60 malt steeped for 72 h. The amount of enzyme production depended on the variety rather than the amylose content in the rice. The optimal condition for malting rice regarding β-amylase activity and α-amylase activity was analyzed at 30°C, with steeping for 24 h and germination for 4-5 days.