What are the processing steps of broken red tea(1)

Red broken tea, also known as finely cut black tea, is currently the main selling variety in the international tea market, accounting for over 95% of the world’s total black tea production and sales. The method of making broken red tea began around 1880 and has developed rapidly over the past century.
Before the 1990s, the production of broken red tea was concentrated in some state-owned tea plantations, with the main production areas being Hainan, Guangdong, Guangxi, Guizhou, and Jiangsu. Guangdong had the highest production, with better quality Yingde black tea and Hainan black tea, which were popular for export. Currently, only a few provinces such as Hainan and Guangdong produce it.

broken black tea (2)

Broken black tea processing

Red broken tea leaves require tenderness, freshness, uniformity, and cleanliness. Fresh leaf processing involves four steps: withering, kneading, fermentation, and drying. Due to the need to achieve the purpose of kneading and cutting, there are significant differences in production equipment, technical conditions, and requirements compared to Gongfu black tea.

1.Withering process

Withering is the most basic process in the processing of broken red tea, and it is an indispensable prerequisite for kneading and cutting. It lays a certain material foundation for the formation of strong, strong, and fresh quality of broken red tea. After fresh leaves enter the factory, they must be withered in a timely manner and appropriate measures must be taken to control the degree of withering. The withering method of broken red tea and the mastery of the degree of withering of fresh leaves in different seasons and degrees are basically the same as the initial production of Gongfu black tea.

(1) Degree of withering

The degree of withering varies depending on the variety of fresh leaves, season, and the type of kneading and cutting machine used. For example, when using a rotary machine for kneading and cutting, due to the good tenderness of spring tea and low temperature, it is advisable to focus appropriately. The moisture content of withered leaves should be between 60% and 62%; Tea withering in summer and autumn is relatively mild, with a moisture content of 63% to 65%. When using LTP hammering machine and CTC machine for kneading and cutting, the degree of withering should be relatively light, and the moisture content of withered leaves should be controlled at around 70%. When using a combination of Lofan and CT machine for kneading and cutting, the moisture content of withered leaves is controlled at 68% to 70%.

The length of withering time is influenced by factors such as tea tree variety, climate, withering method, etc. It is usually determined by the degree of withering, generally not less than 6 hours and not more than 24 hours, with 8-12 hours being suitable.

(2) Precautions for withering

For fresh leaves with different age and tenderness, different dryness and wetness, and different batches entering the factory, they should be withered separately to avoid the phenomenon of wrong grading and disorderly batch. Light withering is recommended for fresh leaves that are aged, tender, confused, or mechanically damaged, as it can reduce endoplasmic reticulum loss. Keep the withering site and tools clean and hygienic. After each withering, they must be thoroughly cleaned to avoid affecting the quality of the next batch of withered leaves. Always pay attention to the airflow, temperature changes, and blade perforation in the withering groove to ensure smooth withering. Regularly check the degree of withering to prevent insufficient or excessive withering. The withering amount should be reasonably arranged according to the throughput of the following processes, achieving coordination between upper and lower processes and balancing production.

broken black tea (3)

2.Rubbing and cutting process

Rubbing and cutting are important processes for the quality formation of broken red tea. By kneading and cutting, it is necessary to finely chop and compact the particles tightly. Adopting fast and intense kneading and cutting techniques to obtain a strong and fresh inner texture.

Due to different types of machines and cutting methods used during kneading, there are significant differences in product quality. The kneading and cutting of red broken tea is significantly different from the kneading and rolling of Gongfu black tea, including kneading, chopping, and breaking into pieces. Red broken tea requires more tightly packed crushed tea particles, which meets the requirements of one-time brewing. Therefore, the kneading and rolling should be sufficient.
However, during the kneading and cutting process, due to the effects of cutting, grinding, and squeezing on the leaves, the leaf temperature often rises rapidly, and the changes in polyphenolic compounds are intense, resulting in a decrease in soluble substances and affecting the quality of broken red tea. Therefore, multiple kneading and cutting steps are used to disperse heat, reduce temperature, and prevent excessive fermentation, in order to obtain a strong and fresh inner essence and increase the amount of broken tea.

(1)Rubbing and cutting machine

There are many types, including disc type kneading and cutting machines, CTC kneading and cutting machines, rotor type kneading and cutting machines, hammer cutting machines, etc.

a. Disc type kneading and cutting machine

Also known as a tablet machine. The appearance and operating principle of the machine are the same as ordinary kneading machines, except that there are 8-12 sharp curved kneading knives on the kneading disc. Cut the tea strips finely during the rotation of the kneading bucket. The cutting effect varies depending on the model, operating pressure, and number of kneading and cutting times. The traditional method of making broken red tea by combining a regular kneading machine with a disc type kneading and cutting machine is called the traditional method.

b. CTC kneading and cutting machine

The main body is composed of stainless steel rollers engraved with concave patterns. The two rollers rotate in opposite directions at different speeds of 700r/min and 70r/min, respectively. The tea strips are twisted, twisted, and cut into granular broken tea through these two rollers at different speeds. The cutting efficiency is high, but the body shape is very different from other methods of kneading and cutting broken tea.

c.  Rotary kneading and cutting machine

rotorvance。 By using a rotor spiral to push the tea strips, it achieves the functions of squeezing, kneading, and twisting, with high kneading and cutting efficiency, a large proportion of broken tea, and compact particles. Various types of rotor machines have been researched and manufactured in different regions based on actual production, which can be roughly divided into four types: blade edge plate, spiral rolling cutting, full spiral, and combination. Each type has its own characteristics in product quality. Medium sized ones include Yingde 25 and Shaodong 27; Small models include Yingde 20, Shaodong 18, Fushan 18, Zhujiang 20, Yangai 20, Maolu 18, as well as models such as Furong 705 and Nanchuan 759.

d.  Hammer cutting machine

LTP(Laurie tea processor)， It is a new type of red broken tea making machinery. There are 160 hammer slices inside the machine, divided into 40 combinations. The first 8 sets of hammers and knives, and the last 31 sets of hammers and knives plus one set of hammers and knives, with a speed of 2250r/min, complete the crushing task within 1-2 seconds. Due to the high-speed impact of the hammer blade, small fragments of uniform size and bright green color are formed and sprayed out, with a size of 0.5-1.0mm. For example, the 6CZ-30 hammer cutting machine cuts fragments with a size of 1.0-2.5mm.

broken black tea (4)

(2) Rubbing and cutting techniques

There are traditional kneading and cutting methods for red broken tea in China, as well as rotary kneading and cutting methods. Due to the limitations of various machine performance, it is difficult to achieve rapid and sufficient damage to leaf cell tissue using a single type of kneading and cutting machine or completing kneading and cutting in one go. To this end, various regions often adopt several types of kneading and cutting machines and matching kneading and cutting technologies, which have played a positive role in further improving the quality of Chinese red broken tea, adapting to international market needs, and enhancing product market competitiveness.

a. Traditional manufacturing methods

Generally, knead the strips first, and then knead and cut them. Require short-term, heavy pressure, multiple kneading and cutting, and multiple tea making.
Withered leaves are first kneaded on a bucket and disc type rolling machine for 30-40 minutes, forming a tight rope. The dough tea and screened bottom tea are then sent to a 55 type disc rolling and cutting machine for 20 minutes. After 5 and 6 holes of block separation and screening, the bottom is the first crushed tea, which can be sent for fermentation. Sift the tea and repeatedly knead and cut it. The second knead and cut it for 15 minutes, the third for 10 minutes, and if necessary, the fourth knead and cut it for 10 minutes. Generally, about 85% of broken tea is taken, and old leaves should not be cut forcefully. When cutting, alternate between applying pressure and releasing pressure. Generally, apply pressure for 7-8 minutes, reduce pressure for 2-3 minutes, and apply more pressure to ensure even rolling and cutting of the leaves, lower leaf temperature, and produce more broken tea.
The frequency and duration of kneading and cutting should be determined according to the temperature and the age and tenderness of the leaves. The temperature is high, so the number of kneading and cutting should be increased briefly each time to reduce leaf temperature. The frequency and duration of kneading and cutting tender leaves can be reduced. The traditional kneading and cutting method can be used to extract mainly from Houttuynia cordata and leaf tea.

b. Rotary kneading and cutting machine method

Compared with traditional kneading and cutting methods, the red broken tea produced by the rotary kneading and cutting machine has the advantages of short kneading and cutting time, high tea crushing rate, tightly packed particles, and fresh and strong aroma. In the 1970s, various types of rotor kneading and cutting machines were improved and promoted in various regions to adapt to different types of fresh leaves. Due to different performance of kneading and cutting machines, different combinations of machine models, and significant differences in cutting degree. For example, the Yingde 7051-50 and Furong 709 models mainly use the function of rolling strips, with some leaves being finely cut; The Yingde 30 type Furong 705 type is mainly used for cutting, and their tea making quality also varies.

There are two forms of combination for different models: one form is that the rolling machine rolls, breaks down and screens the blocks, and then enters the rotor kneading and cutting machine for kneading, cutting, and screening. The screening head is repeatedly kneaded and cut multiple times.

Generally, the 90 type rolling and twisting machine is used to knead the leaves for 30-35 minutes, and the pressure is applied in a “light and heavy” manner (no pressure for 15 minutes → light pressure for 7 minutes → loose pressure for 3 minutes → heavy pressure for 7 minutes → loose pressure for 3 minutes → heavy pressure for 3 minutes). The leaves are kneaded and sieved through 4 and 5 holes, and the resulting tea leaves are classified as Leaf Tea No.1 and No.2 (F.O.P). The sifted tea enters the rotary kneading and cutting machine for kneading and cutting (such as using the Yingde 30, 25, and 20 models), with three cuts and three sieves. After each kneading and cutting, it passes through 5 and 6 sieve holes, and the tea is taken as 1-12-1 and 3-1, respectively. The tea on the sieve is called the tea tail (or tea head), which is controlled below 10%. Another form is to knead the strips with a rolling machine for 20-30 minutes, then use a disc type kneading and cutting machine to knead and cut for 15 minutes. After cutting, the tea is sieved through 5 or 6 holes to dissipate heat, and the tea leaves are sieved to extract fine tips before being sent for fermentation. The sieved tea enters the rotary kneading and cutting machine and is repeatedly kneaded and cut, with the tea tail controlled at the minimum amount.

Both of these methods use a rolling machine to knead the tea strips before cutting, in order to extract some tender tips and strengthen the tightness of the tea strips, resulting in more broken tea after cutting and reducing the amount of flakes. However, the kneading and cutting process takes too long, which affects the color and freshness of the raw tea.

For this reason, later on, direct entry into the rotor kneading and cutting machine was often used for kneading and cutting. This method has a short kneading and cutting time, good cutting effect, good freshness, bright leaf bottom, but less broken tea leaves and more sliced tea leaves.

c. Combination kneading and cutting methods of different types of kneading and cutting machines

CTC machine, LTP machine, and imitation improved hammer cutting machine have the characteristics of strong, fast, and low leaf temperature in kneading and cutting, which can increase the content of theaflavins in red broken tea. Fully utilize the advantages of various types of kneading and cutting machines to achieve the effect of both tightly rolling and fully cutting the particles. Various regions have conducted extensive experimental research on different machine combinations to improve the quality of tea production to varying degrees. There are roughly the following combination methods.

① The combination of rotor kneading and cutting machine and triple CTC has the advantages of fast kneading and cutting speed, short time, and a total process time of 20-30 seconds. At room temperature of 28.5 ℃, the temperature of the cut leaves increases by 2.8-5.5 ℃, while the traditional method generally increases the leaf temperature by 6-7 ℃. Due to the low leaf temperature and short time in the kneading and cutting machine, the oxidation of catechins is slight. After kneading and cutting, the leaves can undergo a suitable fermentation process, and the degree of fermentation can be effectively controlled. Therefore, it is beneficial for the product to obtain concentrated, strong, and fresh quality, and can improve the tea crushing rate.

② LTP and secondary CTC combination: These two types of kneading and cutting machines need to meet the following two conditions for combination kneading and cutting: firstly, the withering degree of fresh leaves should be light, and their moisture content should be maintained at 68%~70%, which is conducive to cutting the withered leaves finely and evenly; Secondly, fresh leaf raw materials require good tenderness. If fresh leaves are divided into 5 grades, grades 1-3 are the best, which can achieve products with smooth appearance and good internal quality.

If the lower grade raw materials are used, the dry tea color will be dull and gray, and the elastic skin sweater will bond with the tea, forming “hairy beard” particles, which are also difficult to handle in precision processing. CTC type coarse aged tea has a strong green and astringent taste. If it is a lower grade fresh leaf raw material, it can be first cut by LTP and CTC machines, and then fed into a rotary kneading and cutting machine, which is more conducive to improving quality.
It must be pointed out that the tea cutting edges of LTP and CTC must be kept sharp in order to produce tea leaves with a smooth appearance and less elastic skin. If the blade is blunt, the cut tea appears as thick slices of tea, revealing the elastic skin of the sweater. Therefore, before the production of broken red tea, it is necessary to check the condition of the cutting edge. If there is significant wear, measures should be taken to ensure the quality of the tea. In production, it is generally necessary to mill and grind the rolling teeth and cutting edge once every 1-2 weeks.

broken black tea (5)

(3) Requirements for the kneading and cutting room

Kneading and cutting require low temperature and high humidity environmental conditions to facilitate the conversion of polyphenolic compounds. Therefore, it is advisable to knead and cut black tea in the morning and evening. In hot and dry seasons in summer and autumn, it is necessary to sprinkle water or spray frequently to increase humidity and reduce temperature. Quick kneading, quick cutting and quick separation are adopted to ensure the quality.

(4) Moderate kneading and cutting mark

  • The tea strips are tightly rolled, with a strip rate of over 80%.
  • The tea juice overflowed fully, and even when holding the tea, the tea juice overflowed from between the fingers.
  • The cell damage rate is 70%~80% for strip tea and over 95% for broken tea.

broken black tea (1)

(5) Precautions for kneading and cutting

a.  Fresh leaf raw materials

If it is a large leaf variety, the rotor machine should be selected with a smaller extrusion force model. In order to extract Houttuynia cordata, after rolling and kneading the strips, it can be disassembled and sieved. The tea at the bottom of the sieve can be taken out, fermented, dried, and then kneaded and cut by a kneading and cutting machine.

b.  Reduce leaf temperature

Withering leaves undergo rolling and multiple cutting processes, resulting in complete damage to leaf cells, increased leaf temperature, and intensified fermentation. Therefore, minimizing temperature is an important measure to obtain high-quality finished tea.

  •  The room temperature in the kneading and cutting workshop is required to be between 22-26 ℃, and the relative humidity should be above 85%. If it exceeds 28 ℃, cooling measures should be taken. During the high temperature season, it is recommended to knead and cut at night.
  • The excessive amount of leaf feeding in the rolling and cutting machines leads to a significant increase in leaf temperature. It is necessary to control the amount of leaf feeding according to the operating procedures. The rolling machine should be pressed and loosened frequently, and the pressure should be reasonably applied, and not pressed to the bottom at once.
  •  If the tea machine and power fail, it is necessary to promptly remove the damaged tea to dissipate heat.
  • The tea leaves kneaded and sieved should be spread as thin as possible to dissipate heat, and processed in a timely manner, without being stacked too thick

c. Remove debris

Metal objects, stones, sediment, and other non tea impurities mixed into tea leaves should be promptly removed. special

Be careful when feeding the rotor kneading and cutting machine to prevent hard objects from damaging the components.

d. Pay attention to hygiene

The workshop should be kept clean regularly, and the tea on the ground should be cleaned at all times without leaving any residue in the next batch of tea.

e. Rapid transportation, kneading and cutting process

If there is no joint installation equipment, the transportation action should be rapid, and the up and down time of each machine’s tea billet should be shortened as much as possible to reduce the residence time of the tea billet between various processes and minimize the loss of contents.

f. Balance production between various processes

Properly plan and arrange, closely connect, and achieve balanced production. Continuous feeding and no backlog are important aspects to ensure tea quality and improve efficiency.