The composition and function of hops hops products and factors affecting the utilization rate of hops and hops in beer brewing important role. Hop addition, extraction, and the latest supercritical extraction process.
Hops hops are known as hops. Germany was the first country to add hops to beer production. Hops are an important raw material for brewing beer, which can give beer a refreshing bitter taste and unique flavor, can promote the clarification of beer and wort, is conducive to the foam of beer, as a preservative of beer. Thus hops are indispensable for brewing beer. Among the chemical components of hops, the main components of beer brewing are hops resin, hops oil, and polyphenols.
The composition of hops
1. Hop resin
The main ingredient in hops is hop resin, which is the main source of bitterness. Hop resins are divided into hard resins and total soft resins. Soft resins are divided into alpha acid, molar acid and molar acid. Bitter substances are soft resins, and hard resins do not play a role in beer brewing.
1.1 alpha acid
α -acid is the most important quality index in hops. It does not have a bitter taste in itself, but when boiling, it can be isomerized into hetero-α -acid with stronger bitter taste and better solubility. Finally, it is hetero-α -acid that gives beer its bitter taste. α -acids and isoα -acids have antibacterial effects in beer, inhibiting bacterial growth at low concentrations and killing bacteria at high concentrations.
1.2 beta acid
Beta-acid, also known as humarone, does not taste bitter, is not heterogeneous, and does not dissolve well in water, but its oxides give beer a strong bitter taste.
2. Hop oil
Hop oil is the main source of hop aroma. Hop oil is a yellow oily liquid that is volatile and insoluble in water and wort. There are two main groups of components: hydrocarbons and oxygen-containing compounds. Hydrocarbons have a side effect on hops, while oxygen is pure and pleasant.
Polyphenols play an important role in beer. Phenols in hops account for 4%-10% of the dry matter, polyphenols have many effects on beer production, the main role is to clarify wort, wort boiled with protein to form a complex, promote protein coagulation.
Polyphenols play a dual role in beer quality. High polyphenol content can easily cause color deepening, turbidity, precipitation and other phenomena, affecting the abiotic stability of beer. When the content is too low, the taste of beer is very light, which is not good for the flavor of beer.
Recently, a substance in hops called xanthohumol has become more famous. Werner Barker, a scientist at the Technical University of Munich, and other scientists have found that xanthohumol has obvious anti-cancer and other benefits.
Hop products
The traditional way to use hops is to add whole hops when wort is boiled, and the utilization rate is necessarily not very high. At present, many breweries use various hop products.
1. Beer pollen
The hops are crushed into beer pollen smaller than 1mm by a grinder, using the same method as adding whole hops. Beer pollen in boiling contact area is large, heat transfer is good, so the utilization rate is high. However, there are advantages and disadvantages, the large surface area of beer pollen is also easier to oxidize, easy to lose.
2. hops
Pellet hops are processed into granules by adding certain additives on the basis of beer pollen. This can not only improve the utilization rate of hops, but also prevent the oxidation and loss of hops active components, killing two birds with one stone. Therefore, pellet hops are currently the most widely used hop products in the world.
3. Hops extract
Hops extract with organic solvents to extract the effective components of hops, in the evaporation of organic solvents, so as to get concentrated resin extract. The advantage of hop extract is to improve the utilization rate of α -acid, and can be more accurate control of the dosage. The largest production and use of the country is the United States and Germany, currently domestic beer enterprises use the most or hop particles.
4. Heterogeneous hops
Isomeric hops are divided into isomeric hops granules and isomeric hops extracts. In order to avoid the loss of α -acid in wort boiling and fermentation, it is necessary to isomerize the α -acid in hops in advance, and then treat it into granules or extract, which can greatly improve the utilization rate of hops.
Factors affecting the utilization rate of hops
1. The boiling intensity of wort
The greater the boiling intensity, the greater the isomerization rate of α -acids in hops, the more heterogeneous α -acids obtained, the higher the utilization rate of hops.
2. oxygen
Hops in boiling, the lower the oxygen content, converted into isoα - acid oxidation decomposition rate is less, the utilization rate of hops is higher.
3. the pH of wort
The higher the pH value of wort, the more α -acids dissolved in wort, the more α -acids isomerized, and the higher the utilization rate of hops.
4. the concentration of wort
The higher the concentration of wort is, the more polymer material will be combined with the formation of isoα -acid, so that the free isoα -acid is less and less, resulting in the lower utilization rate of hops. But at the same time, the wort concentration should not be too low, otherwise it is not conducive to the later fermentation.
5. The amount of 5 α -acid added
When the amount of α -acid was greater than 80mg/L, the amount of α -acid was inversely proportional to the isomerization rate of bitter substances. The higher the addition amount, the lower the isomerism rate and the lower the utilization rate of hops.
The role of hops in beer brewing
Hops are added to the wort when the wort is boiled. It can give beer a refreshing bitter taste and unique fragrance, increase the anti-corrosion ability of beer and improve the biological stability of beer.
The bitter taste of beer is mainly due to the isomerization of α -acid and the oxide of β -acid formed when wort is boiled. The characteristic aroma is mainly due to the oxygen compounds in hop oil. The anti-corrosion ability of beer mainly comes from soft resin in polyphenols. The improvement of beer's abiotic stability mainly depends on polyphenols, which can interact with proteins to form coagulants, which can be removed to improve beer's abiotic stability.
Five, hops add method
1. Whole hop adding method
The principle of adding hops is as follows: when bitter flowers and fragrant flowers are used, first add bitter flowers and then add fragrant flowers; Use the same hops, add old hops first, then add new hops; Add the hops in batches, starting small and then adding more.
There is no unified method for adding hops. Beer factories develop corresponding adding methods according to their own experience and product characteristics. Generally, it can be divided into one-time addition method, two-time addition method and three-time addition method.
1) Secondary addition: Usually the first hops are added 10-15 minutes after boiling begins. Add the remaining hops 10-30 minutes before boiling ends.
2) Triple hop addition: widely used when wort is boiled for 90 minutes. Add the first hops five to ten minutes after the wort begins to boil, the second hops 30 minutes after the wort begins to boil, the third hops five to ten minutes before the wort ends, and the remaining hops. Boiling hops for too long can cause excessive bitterness, so a small amount of hop bubbles can be added before boiling, but not all at once.
There are two main ways to add hops: one is directly added from the manhole; The other is a closed boiling process in which the hops are added to the hop-adding pot, and then the wort from the boiling pot is poured into the boiling pot.
2. Adding method of hop products
(1) the method of adding hops extract: the method of adding hops is basically the same, but the time of adding is a little earlier.
(2) pellet hop addition method: pellet hop is now widely used, because the effective components of pellet hop are more soluble than the whole hop, and the use and storage are more convenient than the whole hop, so it is widely used in the brewery home, and the number of addition has also been reduced.
(3) the method of adding hop oil: hop oil should be dissolved in edible alcohol first, and then added.
3. Amount of hops added
The amount of hops should be determined according to the α -acid content of hops, consumers' preferences and habits, the way of beer fermentation and the type of beer. The amount of hops added can be calculated in two ways. The content of α acid in hops is used to calculate the amount of hops added internationally. However, the calculation method used in China is still the traditional method, which is expressed by the mass of hops added per cubic meter of hot wort, which is directly related to the type of beer. General pale beer to hop flavor and bitter, add more; Strong beer is malt - based, add less. Hop quality as hops quality difference can be added less.
Hops extraction method
At present, organic solvent extraction and carbon dioxide extraction are the traditional ways to produce hops extract. That is, through organic solvent or CO₂ will be hops in the effective components of extraction, and then through the evaporation of organic solvent and concentrated into paste.
Supercritical CO₂ extraction technology developed in recent years has great application prospects. Supercritical CO₂ extraction is the use of CO2 in the critical value above the characteristics of the extraction of spray in a soluble component of a new separation technology. Compared with the traditional organic solvent extraction method, supercritical extraction does not have residual harmful components, and compared with CO₂ extraction, the extraction rate of important components is high, beer flavor is stronger, taste is better, the process is better.
The current situation of hop industry
At present, hops are divided into three categories. The first category is the best fragrant flower, with the average formic acid content reduced and the yield increasing. The second kind is fragrant flower, the yield shows a decreasing trend; The third category is the high formic acid hop box bitter flower, the production showed an increasing trend, highlighting the formic acid bitter taste. It can be seen that the development trend of international hop varieties is that bitter flowers and fragrant flowers tend to be specific.
The main hop producers are Germany, the United States, China and the Czech Republic. According to the international Hop Association disclosure, in 2008 the global hop planting area of 800,000 mu, production of 110,000 tons. Among them, the top three countries: Germany 262,000 mu, output 39,560 tons, accounting for 32.88%, 35.96%; The United States 238,000 mu, production of 34,580 tons, accounting for 29.75%, 31.44%; China 125,000 mu, production of 14,500 tons, accounting for 15.63%, 13.18% respectively. China's hop output is not small, China's hop output the world's third. Although the yield is very high, but our hops are also pure in many problems:
(1) The content of formic acid in hops was decreasing due to its single variety.
The main hop varieties in China are bitter flowers (mainly Qingdao big flowers), and the production of high formic acid hops is less. Because of the long planting time of beer flower seedlings in China, the content of formic acid decreased obviously.
(2) Backward hops processing technology
Hops in China are mainly grown in Xinjiang and Gansu provinces, mostly on reclaimed farms and dispersed by farmers. The conditions for post-harvest processing are poor, making it difficult to process and store hops at low temperature. The loss of formic acid and other active components in hops was more in hops processing. At present, There are abundant hop resources in China, but other hop products, such as hops extract and isomeric hops, have not been produced on a large scale, and the application of hop oil extraction and molar acid is almost blank.
