Determining the exact amount of raw materials is the foundation of successful beer brewing. From malt and hops to yeast and water, every ingredient must be carefully measured and balanced. Taking the production of 1000 liters of beer as an example, to calculate how much malt is needed, we first need to determine the wort concentration and other relevant parameters of the beer we plan to produce.
Wort Concentration
Wort concentration is usually expressed in °P (degrees Plato), which reflects the content of soluble extract in the wort. The common wort concentration is the degree measured by the Brixmeter at 20°C. For example, wort with 12°P means that every 100 grams of wort contains 12 grams of soluble extract (mainly sugar).
Extract Yield
But the extraction rate of these soluble substances is never 100%. We usually use “as is” extract yield and “dry” extract yield to express the ability to extract soluble substances from malt. The malt extract yield is mainly affected by malt variety, milling degree, water quality, soaking time and water temperature.
Original Gravity
Unlike wort concentration, wort density refers to the ratio of the mass of dissolved extract in wort to its volume, usually expressed as original gravity or relative density. Original gravity can also be calculated based on wort concentration. That is, original gravity = wort concentration * 0.004 + 1. The Original Gravity of 12°P wort is about 1.048.
Brewhouse Efficiency
Brewhouse efficiency takes into account all losses throughout the brewing process, not just those during mashing. It measures the efficiency of converting malt potential into fermentable wort that reaches the fermenter. Because the actual brewhouse efficiency can only be calculated after the brewing is completed, and the brewhouse efficiency we use in the early stage of calculating the malt input is an expected value obtained from empirical data. It typically ranges between 65% and 85%.
Calculate the total input of malt required
Malt Input (kg) = planned beer output (L) * Wort Concentration (°P %) * OG / Brewhouse Efficiency
To produce 1000L of 12°P beer, with assuming 85% brewhouse efficiency:
Malt Input (kg) = 1000 * 1.048 * 0.12 / 0.85 ≈ 148 kg
If the malt quality is not high or the equipment cannot support the ideal brewing process, with a brewery efficiency is 75%, we need to use more malt:
Malt Input (kg) = 1000 * 1.048 * 0.12 / 0.75 ≈ 167.7 kg
As you can see, when brewing the same amount of beer, the quality of malt, degree of crushing, brewing process and efficiency will affect the amount of malt input, and thus also affect the cost.
It should be noted that since the wort concentration is measured at 20°C, and the volume of hot wort and cold wort is different, a more scientific calculation requires the addition of a volume conversion factor. In actual brewing, many beer styles use more than one type of malt, and the amount of each malt added must be calculated based on the proportion of these malts and their extraction yields.
