With the development of society and the improvement of people’s health consciousness, tea drinks have gradually become one of the main products of people’s beverage consumption.

Production of Tea Drinks

1.1 Classification

According to the different raw materials, tea drinks can be divided into tea drinks and flavored tea drinks, tea drinks are divided into strong tea and light tea type, flavored tea drinks can also be divided into fruit-flavored tea drinks, juice tea drinks, tea drinks, carbonated tea drinks, milk tea drinks and other tea drinks.

According to China’s national standards for the classification of soft drinks and relevant regulations, tea drinks refers to the water extract of tea or its concentrate, instant tea powder as raw materials, processed and made to maintain the original tea should be flavored tea beverages; juice tea drinks refers to the tea broth by adding water, the original juice (or juice concentrate), sugar, acidifier and other modulations made of products, finished products in the original juice content of not less than 5.0%; fruit-flavored tea beverages Fruit-flavored tea beverages refers to the tea broth by adding water, food flavorings, sugar, acidifier and other modulations of the products; carbonated tea beverages refers to the tea broth by adding water, sugar and other flavored products filled with carbon dioxide; milk-flavored tea beverages refers to tea broth in the tea broth, water, fresh milk or dairy products, sugar, and other modulations of the tea beverages.

1.2 Production process

The production process of liquid tea beverages in different products and packaging forms is different, but the preparation process of tea leaf as the raw material of tea extract is basically the same.

The extraction of the specific process is: from the tea leaves to extract the concentration of tea broth because of raw materials, process equipment, production of different products vary, the ratio of water to tea is generally 1 ~ 15: 100. due to the concentration of large easy to produce white precipitation, in order to reduce the cost and to avoid turbidity phenomenon of the finished product, you can use 1% of the tea leaves for the extraction, the extraction temperature of 70 ~ 95 ° C, the extraction time of 5 ~ 30 min. The extraction time is 5~30min. After extraction, use 250 mesh nylon cloth to filter and remove dregs.

Extraction generally have sandwich pot type, basket cage type and coffee extractor type three forms. Sandwich pot extraction of hot water into the pot with a stirrer heated to the specified temperature into the tea, stirring to a certain time after turning the sandwich pot to pour out the tea extract for filtration. This form of extraction temperature and time is easy to control, easy to stir the material, extraction is sufficient.

Basket cage type extraction is to put the basket cage with tea in the hot water tank by equipment lifting down to play a stirring role in the extraction, but the extraction is not complete, the tea residue is inconvenient to take out, the tea is prone to astringent flavor. Coffee extractor-type extraction or spray, is the tea on the net, with the specified temperature of the hot water from the top of the spray extraction, to be fully impregnated with tea from the bottom of the tea broth, the extraction is easy to discharge slag, but can not be stirred, the end of the extraction is not easy to discern.

Influencing factors of tea beverage quality

2.1 Water quality

The main component of tea drinks is water, so the quality of water has a great impact on tea drinks. Calcium, magnesium, iron, chlorine and other ions in the water can affect the color and taste of tea, which will make the tea beverage turbidity, the formation of tea milk.

For example, when the iron ion content in the water is greater than 5ppm, the tea broth will be black, and bitter taste; and high chloride ion content will make the tea broth has a rotten smell.

In addition, the vegetable tannins in tea can react with a variety of metal ions, and can produce different colors. Therefore, the production of better quality tea drinks must be used to remove the ions of pure water, and the pH value of 7 or so, to maintain neutral, iron ion content of less than 2 ppm, the permanent hardness of the chemical content of less than 3 ppm, in order to ensure that the first fresh color and flavor of tea drinks.

2.2 Raw materials

The different flavors of tea beverages are mainly due to the differences in raw materials. Finished tea due to its different quality of tea, different places of origin and tea production technology, storage of good and bad to form a different flavor, while its soluble components are also different.

The quality of tea green and tea tree varieties, growing areas of soil, sunshine, fertilizer, cultivation methods, collection season, and tea buds moisture has a great relationship.

The quality of finished tea depends on the processing technology on the basis of tea green. Such as the thickness of tea green stacking, fermentation time mastery, baking temperature and moisture control. If the storage is not appropriate, it will cause moisture or mold, which leads to a decline in the quality of tea beverage products.

2.3 Extraction process

In the extraction process, the factors that directly affect the extraction rate of soluble substances in tea and the quality of the extract are the water temperature, extraction time, the size of raw material particles, the ratio of tea to water and the extraction method.

The higher the water temperature, the longer the time, the smaller the raw material particles, the larger the proportion of tea leaves, the higher the extraction rate, the more bitter and astringent tea soup, the higher the cost, and the freshness of the aroma will also be affected.

In addition extraction whether to use multi-stage method, also affects the quality of tea broth. Avoiding and eliminating turbidity and sedimentation in tea beverages is a key technology in the production of tea beverages.

Tea extract will produce white tea milk precipitation after cooling, is generated by the tea polyphenols and their oxidized decomposition of tea and caffeine chromium, this precipitation is also known as “tea creamer”.

In addition, proteins, pectin, starch and other macromolecules are also prone to precipitation, and the ions in the water are the primary cause of turbidity and precipitation.

2.4 Others

Tea drinks are generally blended from a variety of ingredients, a variety of ingredients with different physical and chemical properties, blending improper order of ingredients are caused by chemical changes in some components to generate insoluble substances.

For example, if citric acid and sodium benzoate, a preservative, are put in at the same time when mixing, the sodium ions in sodium benzoate will precipitate under the condition of high acidity of the liquid and produce a large number of white flaky precipitates that are difficult to dissolve in water.

Additives in tea beverages can also affect their quality. Such as color enhancers can improve the color and flavor of the product, if the choice is not appropriate, but will reduce the stability of the product, produce suspensions and precipitates.

Tea drinks in the sweetener quality is also very important, the general use of sucrose, but some of the purity of sucrose is poor, containing colloidal substances and impurities, if not processed for direct use, will produce colloidal substances aggregation and sedimentation.

In addition, microorganisms are also one of the factors that cause the instability of tea beverages. Tea drinks are rich in carbon and nitrogen nutrients for microbial growth and reproduction, if not strictly sterilized, when the total number of bacteria reaches a certain concentration, it will deteriorate and become muddy, resulting in flocculent or lumpy precipitates.

Solution

At present, to solve the problem of chaotic tea beverages, the general use of physical methods, i.e., low-temperature precipitation method, the tea extract is rapidly cooled, so that the turbidity of the tea juice or precipitation after the rapid formation of the tea juice, and then centrifugation or filtration to remove, in order to improve the clarity of the tea juice.

Ultrafiltration, microfiltration and other technologies can also be used to remove large molecules in the tea juice of chemical components such as proteins, pectin, starch, etc., so as to obtain a clear and transparent tea juice. In addition, the use of diatomaceous earth and other adsorbents can also remove macromolecules; or electrodialysis – microfiltration, to reduce the concentration of high-value metal ions and remove macromolecules.

On the other hand, to avoid the precipitation of tea beverage can also use chemical methods, such as adding enzyme preparations, adding colloidal substances.

Add tannase, cellulase, protease or pectinase in tea juice, can make the tea juice in the decomposition of large molecules to achieve the purpose of removing mixed to sedimentation.

In the tea beverage add gum arabic, sodium alginate, sucrose fatty acid lipids and other macromolecular colloidal substances, can make the tea juice in the soluble components of the dispersion has been improved to avoid turbidity at low temperatures, and can improve the color and flavor of the tea juice.

In addition, you can also add sodium hydroxide, potassium hydroxide, ammonium hydroxide, ammonium sulfate, sodium sulfite, sodium hyposulfite and other bases in the tea juice, so that the hydrogen bond between the tea polyphenols and the caffeine complex break, and the tea polyphenols and their oxides to generate a stable water-soluble salt, to avoid the tea polyphenols and their oxides with the caffeine complex, increase the solubility of the macromolecule components. It can promote the formation of tea precipitation, and then adjusted with acid, the tea juice can be increased after cooling and centrifugation to increase the degree of clarification.