Mashing
Regime
General Considerations
• The mashing regime used depends on the plant
available and the types and amount of adjuncts employed.
• The parameters to be specified are the liquor grist ratio, the
pH, the time(s) and temperature(s) at the conversion stand(s) and
the sparge temperature regime.
• A temperature programmed mash should provide more soluble and
amino nitrogen during mashing than is obtained in a constant temperature
infusion.
• When using constant temperature infusion, the lower the stand
temperature the more fermentable the worts and the higher the contents
of total and free amino nitrogen.
Range of Values
• For constant temperature infusion the liquor
to grist ratio is typically 2·3 - 2·8 hectolitre per 100 kg (2·1
- 2·6 barrels per quarter).
• For transferred mashes the liquor to grist ratio is typically
2·7 - 3·3 hectolitre per 100 kg (2·5 - 3·1 barrels per quarter).
• pH is in the general range 5·0 - 5·5 with an optimum of 5·3· Tolerance
on specification is ± 0·1.
• For constant temperature infusion the initial temperature (initial
heat) of the mash is 64° - 67°C (147° - 153°F) (see Appendix 4)
and stand time is typically 0·5 to 1·5 hr.
• During sparging mash stand temperature rises to 70° - 71 °C (158°
- 160°F) (see Topic 6).
Operational Protocols
• Mash temperatures, liquor grist ratios and pH
should be reviewed if the grist composition is changed, e.g. with
new season's malt or with change of barley variety.
• Spent grains should occasionally be examined for residual extract
and unconverted starch. In case of difficulty, for example with
low extract or slow run-off, grains should be examined for signs
of gelatinous beta-glucan.
• If wort separation is impeded check the sparge/underlet temperatures
and the milling of the grist.
Measurement Protocols
• Most variables are measured in process, e.g.
weighing, volume measurement and temperature.
• Mash and wort pH should be measured without delay on a cooled
sample using a standardised pH meter
• Apparent fermentability of wort is measured using the Institute
of Brewing Recommended Method 7·1
• A sample of spent grains should be taken (IoB Recommended Method
7.2.1) and analysed for moisture (IoB Recommended Method 7.2.2),
Soluble Extract (Recommended Method 7.2.3) and Total Available Extract
(Recommended Method 7.2.4) The difference between Total Available
Extract and Soluble Extract is principally due to, and therefore
a close estimate of, the residual starch.
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