Flour diastatic activity

When carrying out these determinations, it will be found advantageous to make control determinations simultaneously on a malt flour or syrup of known diastatic activity. 

The basic principles of flour milling are applied to the production of durum semolina. However, durum milling is different from conventional wheat milling, especially in terms of the usage of more break roll passes and number of purifiers used. The refined semolina contains more ash compared to refined flours from soft or hard wheats. Durum semolina is evaluated based on speck count, protein and mineral contents, color and diastatic activity (Chapter 15). In addition, the... 

Most bread recipes include diastatic barley malt flour. Diastatic malt contains high levels of a- and P-amylases and proteases that mainly hydrolyze damaged starch granules and proteins, respectively. These enzymes gradually and slowly provide substrate for the fermenting of yeast. Diastatic malt is especially important in those formulations where sugar is not used, such as in French breads. Many commercial hard-wheat flours are supplemented with diastatic malt in order to adjust their diastatic activity, usually measured by the falling number assay (Chapter 15). The quantities used vary from 0.1% to 1.25% (Doerry 1995, Kulp and Ponte 2000, Stauffer 1990). 

The pressurometer is a special metal airtight container equipped with a gauge (Figure 15.10) designed to measure gas pressure produced by a yeasted suspension of flour. The test is usually carried out for 5 h under strict temperature conditions (30°C) in a proof cabinet or in a water bath (AACC Method 22-11). The instrument is used to determine yeast activity, although it could be also used to indirectly determine diastatic activity of flours and malts. 

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