Agu R C, Brosnan J M, Bringhurst T A, Palmer G H, Jack F R
The Scotch Whisky Research Institute, Edinburgh EH14 4AP, Scotland.
J Agric Food Chem. 2007 May 2;55(9):3702-7. doi: 10.1021/jf0636059. Epub 2007 Mar 30.
Detailed studies were carried out on the influence of corn size distribution on the values obtained for diastatic power (DP) of commercially malted barley. Malted barley was screened using a screening box, and the DP activities of the different corns retained on the different compartments of the screening box were determined. The malt samples retained on the 2.8 mm screen had the highest DP activity, whereas the small corns (<or=2.2 mm) had the lowest levels of DP activity. When the DP results of the corns retained on the different screens were weighed in relation to the percentages of grains retained on each screen, the results obtained were very similar to those obtained from the mixed, unscreened malt samples. The results indicate that the higher the percentage of large corns in a malt sample, the higher the levels of DP found in the malts. In malt samples from both the Decanter and Maresi varieties/cultivars, regression analysis showed that large corns accounted for 87% of the variation in DP. These studies confirmed that corn size distribution is a very important factor in determining the DP level of malted barley. The study is of commercial significance because within a variety, with a similar range of nitrogen, large corns produce malt of higher DP. When the percentage of large corns is high, this should give extract with improved fermentability (yield of fermentable sugars). The gelatinization properties of different grain size fractions, some of which were malted individually, were also studied using a rapid visco analyzer (RVA), and this showed that kernel size had an important impact on the physical properties and malting performance.
针对玉米粒度分布对商业麦芽大麦糖化力（DP）值的影响进行了详细研究。使用筛选箱对麦芽大麦进行筛选，并测定保留在筛选箱不同隔层上的不同粒度玉米的DP活性。保留在2.8毫米筛网上的麦芽样品具有最高的DP活性，而小粒度玉米（≤2.2毫米）的DP活性水平最低。当将保留在不同筛网上的玉米的DP结果按照每个筛网上保留的谷物百分比进行加权时，所得结果与从未筛选的混合麦芽样品中获得的结果非常相似。结果表明，麦芽样品中大粒度玉米的百分比越高，麦芽中发现的DP水平越高。在倾析器和马雷西品种/栽培品种的麦芽样品中，回归分析表明大粒度玉米占DP变化的87%。这些研究证实，玉米粒度分布是决定麦芽大麦DP水平的一个非常重要的因素。该研究具有商业意义，因为在一个品种内，在氮含量相似的范围内，大粒度玉米能产生更高DP的麦芽。当大粒度玉米的百分比很高时，这应该会使浸出物具有更好的发酵性（可发酵糖的产量）。还使用快速粘度分析仪（RVA）研究了不同粒度级分（其中一些是单独发芽的）的糊化特性，结果表明粒度对物理性质和发芽性能有重要影响。
