Diastatic power

The analysis of maltose syrups is carried out similarly to that of glucose, determinations of the reducing sugars and dextrin being of particular importance. With malt extracts, a determination of the diastatic power may also be required. 

Diastatic Power.—This determination consists in a test of the saccharification of starch by means of the substance and may be carried out as follows 1 ... 

On the other hand, 2 grams of the substance are dissolved in 100 c.c. of water and determinations made of the liquefying power, that is, of the capacity of the substance to render starch soluble and of the true diastatic power, that is, of the capacity to saccharify starch. 

If the colour is a little darker than that of the original honey solution, that is, from yellow to greenish or brownish yellow, the whole of the starch is saccharified by the diastatic enzymes of the honey if, however, the liquid is more or less dark blue, saccharification has not taken place and diastatic enzymes are absent or have been destroyed. Finally, if the colour is red or brownish red or brown, a weakening of the diastatic power is indicated, this transforming the starch only into dextrin this is what happens with more or less heated centrifuged honey or with mixtures of natural with artificial honey. If the results are uncertain, the test should be repeated. 

Figure 4. Effect of gibberellic acid on diastatic power...

Amylase Solution Dissolve into 5 mL of water a quantity of (3-amylase, free from a-amylase activity (Sigma Chemical Co., Catalog No. A7005), equivalent to 250 mg of 13-amylase with 2000° diastatic power. 

Special Starch Use starch designated as Starch (Lintner) Soluble (Baker Analyzed Reagent, Catalog No. 4010). Before using new batches, test them in parallel with previous lots known to be satisfactory. Variations of more than 3° diastatic power in the averages of a series of parallel tests indicate an unsuitable batch. 

Other Enzyme Preparations Prepare a solution so that 10 mL of the final dilution will give a diastatic power (DP) value between 2° and 150°. 

Calculation One unit of diastase activity, expressed as degrees diastatic power (DP°), is defined as that amount of enzyme contained in 0.1 mL of a 5% solution of the sample enzyme preparation that will produce sufficient reducing sugars to reduce 5 mL of Fehling s solution when the sample is incubated with 100 mL of the substrate for 1 h at 20°. 

Diaminohexanoic Acid Hydrochloride, 229 Diammonium Phosphate, 27, (S3)4 Diastase Activity (Diastatic Power), 793 Diatomaceous Earth, 120, (S2)8 Diatomaceous Silica, 120, (S2)8 Diatomite, 120, (S2)8... 

Other Uses. Malt is sold and used on the basis of its diastatic power as determined by estimating the maltose formed through the action of endogenous and a-amylases during a standard incubation period. 

In this country, the ordinary six-row barley is the kind most abundantly produced, being raised extensively in the States of the Mississippi Valley. Its relatively high protein content causes it to produce malt of high diastatic power, and thus fits it especially to use in the distillery. 

On the other hand, where high diastatic power is not so... 

A number of important methods are based on the oxidation of sugars by ferricyanide ion in alkaline solution. The method is open to the same objections as the copper reduction methods, namely, the lack of a stoichiometric reaction and the dependence of the method on arbitrarily chosen conditions. The ferricyanide may be used to titrate the sugar solution directly by the use of picric acid or of methylene blue as an indicator. Or, the reduced ferrocyanide may be precipitated as the zinc salt, and the excess ferricyanide determined iodometrically. The Hagedom-Jensen method and the Hanes modification utilize the latter procedure. In the Folin-Malmros micro method, Prussian blue is formed and determined colorimetrically. Extensive application of the ferricyanide method has been made in the determination of the diastatic power of amylase preparations and in blood analysis. 

Dark malts rich in melanoidins and poor in diastatic power are used for brewing dark, rich, aromatic, and full-bodied lagers. The kilning program starts at low temperature (38°C), and when the moisture drops to 15% to 25%, the temperature is increased to 75°C and then to 87°C to 105°C... 

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