Discussion Points on Malt Specification
Malt should be relatively well-modified with even modification and uniform grain size.
Malt analytical values depend on barley variety, malting conditions including use of additives, kilning conditions and equilibration of malt (i.e. period after kilning).
Laboratory analysis is used to establish malt quality and other physical and chemical properties of malt. Care should be taken to ensure that the analytical values specified match the brewing conditions to be used such as the use of cereal or copper adjuncts and the required nitrogen content of the wort.
Range of Values
A wide range of values of total nitrogen may be used and will lead to a considerable variation of extract values (see table below). Particular specifications will depend on the amount and kind of adjuncts employed. Other quality criteria should ideally fall within a narrow range (see table below).
Barley variety is agreed with the supplier but is normally chosen from the Institute of Brewing recommended list (see Appendix 1). Use of a single variety is preferable; mixed varieties, when used, must be compatible in malting character and grain size.
Malting should produce a friable and consistently modified product for which four to five days germination is a good guide line. The use of gibberellic acid, bromate or sulphuring is agreed with the supplier.
The period between kilning and use is agreed with the supplier but is usually 3 weeks minimum. Malt should be inspected visually and by hand on arrival at the brewery to check the extent and uniformity of modification (see also Appendix 1, for use of the Friabilimeter).
Malt is sampled using the Institute of Brewing Recommended Method 2.1. The analytical parameters which should be measured are listed in Table 4.
Malt should be checked visually and by hand on its arrival at the brewery.
Typical Ranges of Values for Malt Specifications
|Hot Water Extract (° per kg dry basis)||Min 302 (High TN Malt, ca 175 mgs/ltr) to 312 (Low TN Malt ca 140 mgs/ltr)||-4|
|Moisture (%)||2·7 – 3·3||+0·2|
|Colour (° EBC)||4 – 6||±1|
|Total Nitrogen, TN (% dry basis)||1·45 – 1·75||+ 0·03 (Low TN) + 0·05 (High TN)|
|Soluble Nitrogen Ratio||38 – 40||±2|
|Free Amino Nitrogen (mgs/ltr @ 1040 gravity)||140 – 175*||±10 (Low TN) to ±15 (High TN)|
|Screenings, < 2·2 mm, %||1·5 – 2·0||+0·5|
|Corns > 2·5 mm, %||93 – 95 dependent upon variety and season||-3|
|Ungerminated grains, %||Target 0, dependent upon season||+2|
|Cold Water Extract, %||18 – 19||±1·5|
|Diastatic Power (° IoB)||35 (Low TN) to 55 (High TN)||±7 (Low TN) to ±12 (High TN)|
Precise specifications, which should be balanced, will be agreed between supplier and customer. It is important that analyses are consistent between batches.
*As measured in laboratory worts which, because of factors such as mash thickness, contain less FAN than do the brewery worts. These values are consistent with a FAN content of 160 – 190 mgs/ltr in the brewery wort.
Analytical Techniques for Malt
|Hot Water Extract, HW||IoB Recommended Method 2.3|
|Moisture||IoB Recommended Method 2.2|
|Colour||IoB Recommended Method 2.4|
|Total Nitrogen, TN||IoB Recommended Method 2.8|
|Soluble Nitrogen Ratio||IoB Recommended Method 2.9|
|Cold Water Extract, CWE||IoB Recommended Method 2.5|
|Diastatic Power, DP||IoB Recommended Method 2.6|
|Free Amino Nitrogen, FAN||IoB Recommended Method 8.3 (see note1)|
|Screenings and Corn Size||Analytica – EBC method 2.7|
|Husk Character||Visual Inspection|
|Ungerminated grains||Visual Inspection|
|Molds||Visual Inspection (see note 2)|
|Filtration Volume||See Appendix 5|
1 Measured on laboratory wort produced by the IoB Recommended Method 2.3
2 Check taste and smell in case of contamination by moulds