The relationship between malt quality and beer quality

In the actual production process, according to the current experience, the quality of malt involved in the extraction rate, coarse and fine powder difference, saccharification time, filtration time, chromaticity, total nitrogen, Courbach value, boiling wort chromaticity, etc. Technical indicators directly affect the quality of beer, we will now describe the quality of malt to everyone.

1. Leaching rate

The amount of malt leaching rate depends on the original barley variety, which is related to the year and location of its planting, and also has a certain relationship with the protein content. The high-quality malt leaching rate is usually specified at 79.5%~81%. The leaching rate is very important. If the leaching rate is not measured, there is no need for malt analysis. Technically, low leaching rates are often due to insufficient protein solubilization. The higher the protein solubility, the higher the leaching rate, and the higher the leaching rate does not mean that the carbohydrates are dissolved well, so the leaching rate is an important parameter, and it is more important that the cells are lysed well and uniformly.

2. Thick and fine powder difference

The difference between coarse and fine flour indicates the degree of solubilization of the barley cell wall. The small difference between the thickness and the fine powder means that the cell wall is dissolved well, which is beneficial to the filtration and improvement of the saccharified wort. The fineness difference of high-quality malt is less than 1.9%, and the yield of beer can be improved by using malt with low fineness difference.

3. Saccharification time

Although saccharification is the result of the combined action of α and β amylase, the saccharification time can still indirectly indicate the amount of α-amylase in malt. If the mashing time of light-colored malt exceeds 10~15min, mashing will be difficult. Poorly dissolved malt will prolong the mashing time. Properly increasing the degree of soaking, implementing low temperature and long time germination, and increasing the concentration of carbon dioxide in the wheat layer in the later stage of germination are beneficial to the formation and accumulation of enzymes, and improving the activity of enzymes can shorten the saccharification time.

4. Chroma

Chromaticity is used as a general indicator in the line standard, and the light-colored malt chromaticity requires 2.5~5.7EBC. However, with the popularity of light-colored beer, the brewery's emphasis on malt chromaticity seems to have become the primary factor for each indicator. Some manufacturers It is required that the lower the malt chroma, the better, which is objectively contrary to the background color and roasting color of barley. Some manufacturers believe that the appearance of malt is bright and white, and the malt chroma is light. We analyzed the small samples collected. Although some malts have bright white appearance, the measured malt chromaticity is as high as 9.5EBC. For chromaticity, the domestic laboratory testing facilities are different. There is EBC colorimetry. The same malt sample may be used in different laboratories. There are the following readings: 3.0, 3.1, 3.25, 3.3, 3.5EBC, of which 3.0EBC and 3.5EBC may be caused by visual errors, and 3.1, 3.25, and 3.3EBC are estimated readings caused by errors. In addition, there is iodine solution colorimetry, which has large operating errors and should be eliminated, so EBC colorimeter should be used uniformly. The color plate is calibrated regularly, and it is recommended to gradually adopt the EBC digital display meter.

5. Boil the shade

The industry standard for boiling chromaticity requires the temperature of glycerin to be 108℃±2℃. According to our test, it is difficult to guarantee such accuracy. Once the temperature of glycerin rises, it will take a long time to fall again. In addition, the temperature of the upper, middle and lower layers of glycerin is quite different, and some experiments The chamber adopts saturated saline water as a constant temperature water bath, the temperature in the boiling state can reach 108 ℃±1 ℃, and the temperature at each point is the same, the effect is possible, but the initial temperature needs to be unified. The correlation between boiling chromaticity and finished beer chromaticity is very good, so the soluble nitrogen value is reversely checked. Usually, the maximum boiling chromaticity of light-colored malt is 7EBC. The measured values of different laboratories are often very different, indicating that this determination Be very careful to do it well. As a general principle, the boiling chromaticity of different batches of malt should not change too much, otherwise the chromaticity of the beer will be too different.

6. Total nitrogen

In order to determine the Courbach index, it is necessary to know the protein content of malt. The influence of protein content on beer output is well known. The higher the protein content, the lower the beer output, but the impact of protein content on beer quality is more than people The extent assumed is much lower, looking at the protein content alone, there is actually no effect in a fairly large range (10% to 12%), it is important to evaluate together with soluble protein.

7. Soluble nitrogen

Soluble nitrogen is an important indicator to measure the degree of protein solubility, which has a great impact on the quality of wort. The soluble nitrogen of malt should be neither too high nor too low, 650~750mg/L is suitable. If the value is lower than this range, the protein solubility of the malt is too low. Although this has no effect on fermentation and yeast reproduction, it will reflect the type of aroma of the beer, such as increasing the ethanol content, but if the soluble nitrogen content is too high , The aroma type will not change, but it will affect the taste of beer, especially the wine will be mellow. Using unmalted grains and reducing the dissolved protein content can give the beer a "dry" taste. This effect can also be achieved by using malt with low protein solubility, which also makes the beer lighter. Glycation has half of the effect on protein dissolution, so the protein of malt is particularly important.

8. Courbach value (index)

The Culbach index refers to the ratio of soluble nitrogen to total nitrogen, expressed as a percentage. The index is usually specified as 38% to 45%. If total protein deviates from the usual 10%–11% content range, more attention should be paid to soluble nitrogen rather than the Courbach value.

9. pH value

The pH value represents the acidity of the malt. The pH value of the malt is usually around 5.90. This value will be reduced to 5.75 when the sulfur-containing raw material is directly heated in the heating furnace. The low pH value increases the activity of most of the enzymes in the mashed mash, so it also obtains a higher leaching rate and a better 45°C Harmony value, but more protein dissolves, and indirect heating is now generally used, and the pH value will be in the Between 5.85 and 5.90, pay attention to the pH value measurement: ① The pH meter should be calibrated before use every day. The temperature difference between the calibration temperature and the temperature during use should not exceed 1 °C. Since many laboratories do not have air conditioning, the temperature difference between winter and summer is large. There is a large error in the pH value test. ②The constant temperature of 20°C should be used for calibration and measurement, and the reported pH value should also be uniformly specified as the measured value at 20°C. The pH value without temperature limit is meaningless.

10. Brittleness

The brittleness reflects the solubility and brewing performance of malt, and is generally required to be above 80% internationally. During laboratory measurement, the roller distance and screen should be checked regularly, and the comparison test between laboratories should be carried out regularly. After the malt is stored and transported, the moisture content and the thickness of the husk are different, which will affect the test results. Therefore, the acceptance of commercial malt should be carried out. Depending on the moisture content of the variety, the year-on-year acceptance is carried out, and the analysis value of the brittleness of the malt produced by the manufacturer can be used as the quality proof.

11. Viscosity

The viscosity of wort is related to solubility, and the viscosity value exceeding 1.67mPa·s indicates poor cell lysis. Viscosity lower than 1.48mPa·s indicates excessive dissolution.

12. α-Amino nitrogen

α-Amino nitrogen refers to amino acid low molecular nitrogen, α-amino nitrogen is of great significance to the composition of wort and beer fermentation, and is the main nitrogen source required for yeast fermentation. The main factors affecting the content of α-amino nitrogen in malt were the quality and characteristics of barley, the degree of immersion, the temperature and time of germination, and the temperature and time before drying. Such as low malting degree, too high temperature in the early stage of germination, too low in the later stage, high temperature in the early stage of drying, too fast heating, high coking temperature and long time, etc., the content of a-amino nitrogen in malt will be reduced.

13. Saccharification power

The saccharification power industry standard QB-1686-93 puts forward clear requirements for saccharification power, and it is evaluated as a limited index. The low malt saccharification power is because the original barley itself has low saccharification power, low protein content, short germination time, low germination temperature, and drying temperature. High, the temperature rises too fast, the coke temperature is high, and the time is long. Maltosification power is too high because of low drying temperature, low coke temperature, short time, and high moisture content. This malt lacks aroma, and the wort is difficult to filter and cloudy. Beer is prone to turbid precipitation.

Malt is the main raw material for the production of beer. High-quality malt is the material guarantee for the production of high-quality beer. How to produce high-quality malt is a subject for beer science and technology workers, and it is worth our unremitting efforts to explore. It's worth moving forward step by step.