Beer is a very popular alcoholic beverage in the world. It is brewed with malt, water and hops as the main raw materials and brewed by brewer's yeast. my country's beer production accounts for about 24.5% of the global production, and the consumption in 2019 was 37.963 million kL, with a huge market capacity. Beer is both an ordinary beverage and a high-energy food. The various functional ingredients it contains have the effects of promoting human gastrointestinal metabolism, blood circulation and diuresis.
Beer is mainly divided into two categories: industrial beer and craft beer. Traditional industrial beer has a large output, and the raw materials used are single and cheap. The brewed products have a single taste and low nutritional value, and the homogeneity between products is very serious. Craft beer uses high-quality and abundant raw materials, and the brewed beer has a rich taste, high nutritional value and more novelty. With the improvement of people's awareness of healthy eating and the adjustment of dietary structure, craft beer has gradually been sought after by beer lovers. The structure of my country's beer production has changed since 2014. The output of industrial beer has gradually declined. At the same time, the number of craft beer manufacturers has begun to increase. In fact, before 2014, some local craft beer brands such as "Master Gao" and "Beijing A" emerged in my country, and they are still increasing. In order to better communicate and exchange between brands, professional organizations and associations have been established to carry out exchange activities from time to time. However, due to the late start of craft beer in my country, the production scale and process conditions are relatively backward, and there is a lack of corresponding national and industry standards, which leads to uneven quality of craft beer products and great safety hazards. Jiang Suying believes that my country's craft beer needs to be improved in terms of process technology and quality control; it should enhance its own innovation ability and talent training, optimize raw materials and control processes, and improve relevant laws and regulations.
Tea is a traditional Chinese beverage. Tea contains active substances such as caffeine, theanine, tea polysaccharides, and tea polyphenols. It has physiological effects such as anti-oxidation, tumor prevention, radiation protection, nerve protection, lung damage relief, and inhibition of melanin formation. Tea is divided into six categories according to the different processing methods, and each type of tea has its own unique taste and aroma. Tea and hops have similarities in some sensory properties. For example, catechins and caffeine in tea are bitter, which is similar to the -acids (humulone, cohumulone, plus humulone, prehumulone and posthumulone) and B-acids (syn-lupulone, ortho-lupulone and plus humulone) in hops. Therefore, using tea and hops to brew beer can reduce the amount of hops while obtaining the special flavor and functional characteristics of tea, thereby reducing the brewing cost of beer.
Tea beer is made of tea, malt, water and hops as the main raw materials. After pre-treatment such as saccharification, filtration and boiling, it is processed through brewing processes such as fermentation, filtration and packaging. Tea beer started late in my country, and the research depth is not enough. There are still many problems in flavor and appearance, such as the fermentation technology, clarification technology and pre-treatment of raw materials of tea beer. There is still a lot of room for improvement in the future, and there is still a long way to go before productization and market production. Therefore, in response to these situations, this article reviews the research status and existing problems of tea beer brewing technology in recent years, and puts forward the main development direction of tea beer in the future, providing some theoretical references for the research and development of tea beer, helping the development of the beer and tea industries, and improving the value and utilization rate of tea resources.
Preparation of wort: After the malt is crushed, it is mixed with water in a certain material-liquid ratio to obtain wort. The wort is saccharified in stages. The saccharification starting temperature is 30-35℃, then the temperature is raised to 50-55℃, and the protein rest begins for 30-40min; then the temperature is raised to 65-68℃ for saccharification for 60-80min; the temperature is slowly raised to 72℃ for 20min; and finally the temperature is raised to 76-78℃ for 10min. The saccharified wort is repeatedly filtered through a filter tank until the wort is clear, then boiled for 60-120min, and tea leaves and hops are added at the same time. The boiled wort is pumped into the cyclotron sedimentation tank along the tangential direction using a delivery pump, so that the wort performs a decelerating cyclotron motion in the tank, and the heat coagulants generated during the boiling process are precipitated in the center of the bottom of the tank by gravity and centrifugal force. The precipitated wort is cooled by a plate heat exchanger or a coil heat exchanger, etc., and then pumped into the fermentation tank.
Fermentation of tea beer: Inoculate a certain amount of activated yeast (1.0x10-3.0x10 cells per ml) into the cooled wort, and carry out the main fermentation at 10-20℃ for 6-10 days. After the main fermentation is completed, the post-fermentation is carried out at 0-4℃ for 5-15 days. (3) Clarification of tea beer: After the fermentation, the tea beer contains a small amount of suspended matter, which is filtered using a plate-and-frame diatomaceous earth filter to obtain clarified beer.
The pretreatment of tea beer includes the selection and addition of tea and hops, the crushing of malt, the saccharification, boiling, and filtration of wort. The pretreatment not only affects the fermentation rate and clarity of the product, but also affects the final flavor and taste.
Adding tea leaves during the brewing process of tea beer not only gives the beer the flavor of tea, but also introduces the functional components of tea, enriching the flavor of tea beer while increasing its nutritional value. Different types of tea have different flavors, tastes and functional components, so the flavors and physiological functions of tea beer fermented from them are very different. Sun Liangyun developed a green tea beer with a sweet and refreshing taste, light color and unique fragrance by adding green tea, giving the beer a rich green tea flavor. Among tea products, in addition to the six major types of tea, there are some other types of tea, such as scented tea, which has a richer aroma and a strong floral fragrance. In order to make the aroma of tea beer more unique, Xia Zhongchen developed a jasmine tea beer with a light beer style and jasmine tea flavor by adding jasmine tea, giving the tea beer a strong jasmine aroma and health care function. In addition, adding beneficial mineral elements to beer is also beneficial to beer. Tao Shuaiping ensures the hygiene and safety of selenium-rich tea beer by adding organic selenium-rich tea. At the same time, researchers also coordinate the flavor of tea beer by adding a variety of teas to make up for the shortcomings of adding a single tea. Yu Shujuan and others found that simply using Kudingcha to replace hops will make Kudingcha beer bitter and uncomfortable; after adding black tea, the brewed tea beer has a richer taste. Compared with traditional beer, tea beer has obvious advantages in flavor, color and nutritional value, which effectively improves the economic value of beer and is more popular among consumers. In addition, when selecting tea raw materials, less famous tea should be used, and more summer and autumn tea should be used, which can not only reduce the cost of tea beer, but also solve the problem of low utilization rate of summer and autumn tea in my country.
Tea and hops are the sources of the main flavoring substances in tea beer. Hops are called "the soul of beer". Its main function is to increase the taste and aroma of beer and inhibit the growth of miscellaneous bacteria during fermentation. The main ingredients are α-acid, B-acid, hop essential oil and polyphenols (Table 1). Tea contains bitter substances such as caffeine, catechins and flavonoid glycosides, and aroma substances such as fatty alcohols, aromatic alcohols, aldehydes and esters, which can provide special taste and aroma components for tea beer; in addition, substances such as tea polyphenols have antibacterial functions and can improve the stability of beer products.
| Table 1 The main components and functions of hops in beer | |
| Active ingredient | Major functions |
| α-acids and their derivatives | Provides bitterness to beer, has the ability to inhibit bacteria during brewing, and improves the stability of beer foam |
| β-acids, xanthohumol and their derivatives | After isomerization, it gives beer a soft bitter taste |
| Hop polyphenols | Improve the mellowness of beer, promote bitterness, improve the non-biological stability of beer, and deepen the luster of beer |
| Hop essential oil | The main source of wine aroma, providing a pleasant aroma for beer |
The time and method of adding tea have a great influence on the flavor and stability of tea beer. The time of adding tea is mainly divided into before fermentation and after fermentation. Adding tea before fermentation is mainly to blend the characteristic components of tea with the body of wine; adding tea after fermentation is to retain the aroma components of tea, because the temperature of the body of wine is lower after fermentation, which is more conducive to the retention of aroma components.
| Table 2 Adding types, amount, method and time of tea in tea beer | ||
| Types of tea | Addition levels | Mode and time of addition |
| Green tea | 2% | Green tea extract (10 min soaking in 80℃ water); add 1/3 during wort cooling, 2/3 during main fermentation |
| 2.5% | Tea extract (after grinding, soak in a microwave oven at a material-liquid ratio of 1:20 for 6 min, then extract in 50℃ water for 10 min and filter with 400 mesh filter cloth); add after the juice is boiled | |
| 3 g·L-1 | Tea extract (boil tea leaves for 12 min); add during boiling | |
| 0.1%~1% | Tea powder; add 0.1%-1% of the total amount of wort at the end of boiling, add 1% when the apparent fermentation degree of main fermentation is 50%~70% | |
| 0.8% | Tea essence (tea leaves are crushed to 40 mesh in a grinder, put into a container filled with 80℃ water, stir and soak for 5 min, the temperature drops to 30~40℃ and maintains the temperature for 20min, and a 20%-30% concentration of tea essence is obtained through membrane technology); added before wort fermentation | |
| Black tea | 4 gL-1 | Tea leaves: added after boiling for 80 min |
| Black tea | Black tea 10% | Tea powder (black tea: Tieguanyin tea is dried at 40-55℃, mixed raw tea is obtained according to the mass ratio of 1:1, and crushed to 200 mesh in a grinder); added before wort fermentation |
| Ticguanyin | Ticguanyin 15% | |
| Dark tea | 1%~1.5% | Tea leaves; added after boiling for 60 min |
| Fu brick tea | Fucha granules 3%, Fucha extract 5% | Fu tea granules, Fu tea extract (tea-water ratio 1:100, ultrasonic extraction at 60℃ for 30 min); Fu tea granules are added during boiling, and Fu tea extract is added in the post-fermentation stage |
| Kuding tea | 8% | Kuding tea powder; added after boiling for 20 min |
| 2.5% | Tea extract (tea-water ratio 1:40, extraction at 90℃ for 30 min) ;Add after the wort is finished | |
| 2 gL-1 | Kuding tea powder;Add 10 minutes before the end of the wort boiling | |
| Jasmine tea | 15%~20% | Jasmine tea powder;Add during the fermentation process |
| 2% | Jasmine tea extract (add 80℃ pure water with a material-liquid ratio of 1:80 and soak for 10 minutes);Add 1/3 during the cooling of the wort, and add 2/3 during the main fermentation | |
The main ways to add tea are adding tea extract, directly adding tea and adding tea powder (Table 2). The concentration and extraction method of tea juice affect the quality and production cost of tea beer. Before adding tea juice to wort, the concentration and extraction process of tea juice extract should be effectively optimized. Ding Yong and others found that the Pu'er tea beer directly added with Pu'er tea has problems such as yellow or light yellow brown color, insufficient tea aroma, turbidity, large amount of Pu'er tea, and unclear unique color and aroma. In order to solve this problem, a tea juice specially made for Pu'er tea beer was prepared. The product brewed with this tea juice has the advantages of aroma, good taste and coordinated color, which is more conducive to the brewing of tea beer. The fusion efficiency of the characteristic components of tea and wort and the retention of the characteristic flavor of tea in beer are the key indicators for evaluating the success of tea addition. In order to brew special tea beer, some researchers use the method of adding tea twice. For example, Gao Xueling found that adding tea leaves at the end of the wort boiling, and then adding tea powder when the apparent fermentation degree is 50%-70%, can not only effectively dissolve the components of tea leaves, but also retain the aroma components in tea leaves, making the aroma of tea beer more intense; Ji Xiaoming and others used the method of adding tea twice when developing Fucha beer. The first time was to crush the Fucha tea and boil it with the wort, and the second time was to sterilize the Fucha tea after ultrasonic extraction, and add the sterilized Fucha extract after fermentation; Zhao Weiwen significantly reduced the bitterness of tea beer by adding tea leaves twice. The purpose of choosing different addition methods and times is to allow the components in tea leaves to be better integrated into beer and ensure the quality of tea beer. The high-temperature boiling stage of wort is the best time for the dissolution of soluble components of tea leaves, but due to high-temperature evaporation during this period, a large amount of tea aroma components will be lost, while adding tea leaves during the fermentation stage can better retain the aroma components of tea leaves.
