Tea undergoes processes such as hot water extraction, filtration, storage, blending, sterilization, and filling, especially the high-temperature effects of extraction and sterilization, resulting in significant loss or destruction of its aroma components. The biggest issue with the quality of these drinks is the lack of aroma from freshly brewed tea. Conventional extraction techniques cannot sufficiently soak and capture the aroma and flavor characteristics of tea, especially the head aroma.
01
Processing causes loss of aroma
After analyzing the changes in aroma components of canned green tea drinks after sterilization, researchers found that after sterilization, the content of cis-3-hexenol, linalool oxide, and nerol in the tea drinks decreased; The content of geraniol and benzyl alcohol increased; The content of compounds such as β - ionone, 4-vinylphenol, and indole also increased significantly. This is due to the heating and decomposition of glycosides in tea, which leads to an increase in compounds such as enols and benzyl alcohol, disrupting the balance of aroma components in green tea and ultimately resulting in the production of a hot soup flavor. Another study on the aroma changes during the processing of green tea beverages has shown that using the SDE method to extract aroma components, the total amount of low boiling point aroma components, total amount of high boiling point aroma components, and total amount of all aroma components after extraction were reduced by 47% compared to those treated with reheated green tea 44%, 39% 0% and 40% 86%. The FI index is smaller than that of the reheating treatment, resulting in a decrease in aroma quality and a decrease in aroma quality. Research also shows that the higher the extraction temperature and time, the greater the loss of aroma component content. The effect of UHT sterilization on the aroma components of green tea raw materials is also very significant. After thermal sterilization at 137 ℃ for 4 seconds, the total amount of low boiling aroma components increases, while the content of high boiling aroma components decreases, leading to a decrease in the FI index and a decrease in aroma quality, resulting in a clear cooked soup flavor. The processing of instant tea and tea concentrate must go through the processes of extraction, coarse filtration, cooling, fine filtration or centrifugation, vacuum concentration, blending, sterilization and spray drying. Traditional instant tea processing techniques can result in excessive loss of tea aroma. Research and production practice have proved that the tea after hot water extraction has almost the same fresh aroma concentration as the freshly brewed tea, but in each subsequent process (such as extraction, filtration, thermal concentration, sterilization and spray drying), due to heating, vacuumizing, oxygen and pump transportation, each process has aroma loss, especially the vacuum concentration and spray drying processes, resulting in the production of Instant Powder or tea concentrate, whose aroma intensity is almost 10% to 20% of the fresh brewed tea. The most severely damaged are the low boiling volatile components with "fragrant" characteristics. The study on the aroma changes of instant green tea during processing showed that after the extraction, concentration and spray drying of green tea, the aroma components, aroma component composition and sensory flavor showed a significant downward trend. Compared with green tea raw materials, there are 59 aroma components in the raw materials, and the total amount of aroma components in the extract has been lost by 35.63%, while 47 aroma components have been retained; The total loss of aroma components in concentrated juice was 82.03%, and 35 aroma components were retained; After spray drying, 94.78% of the total aroma components were lost, and only 6 aroma components were retained. The aroma of the finished instant green tea is almost exhausted, and its aroma and flavor characteristics no longer exist.
02
Aroma improvement technology
1. Utilize multiple varieties of green tea to combine the aroma of new tea beverages
China's tea production areas are vast, with numerous varieties and diverse environmental conditions, resulting in different aroma types of tea. Different tea varieties, origins, seasons, cultivation conditions, the age and tenderness of raw materials, and different processing techniques of the same tea category all have different effects on the aroma of tea, forming a unique tea aroma. The main types of tea in China are black tea, green tea, green tea, and floral tea, among which green tea is the most common. Green tea is the most abundant type of tea in China. It is made from fresh leaves through three processes: blanching (frying or steaming), kneading, and drying. Some green teas have a light and elegant aroma (head aroma), some have a strong and long-lasting aroma (base aroma), some have a tender aroma, and some have a nutty aroma. Therefore, by utilizing the unique characteristics of different green tea varieties and combining them, a new type of green tea beverage aroma can be created, which is one of the effective measures to improve the aroma of tea beverages. 2. Using ultrafiltration membranes and reverse osmosis membranes instead of vacuum concentration for concentration
By utilizing the characteristics of reverse osmosis membranes, under the condition of no phase change in tea, the goal of concentrating tea can be achieved, and to some extent, the loss of tea aroma can be reduced, improving the aroma quality of Instant Tea Powder. Especially the tea concentrate produced by combining UHT and sterile filling technology has a better aroma than instant tea powder. 3. Using freeze-drying technology to dry tea powder
Firstly, freeze 25% of the concentrated tea juice, with a freezing temperature of -25 ℃ and a freezing time of ≤ 2 5 hours, and then at a vacuum degree of 66 Heating at 7-266.6 Pa causes the moisture in the material to sublimate from solid ice to steam, resulting in dehydration and drying of the material. Freeze drying is considered an effective measure to reduce the loss of tea aroma. The GC-MS method was used to analyze the aroma components of oolong tea extract, spray dried powder, and freeze-dried powder. The results showed that spray dried powder could detect 46 components, freeze-dried powder could detect 52 aroma components, and the extract could detect 52 aroma components. According to sensory evaluation, the flavor of freeze-dried powder is better than that of spray dried powder.
4. High temperature reheating treatment
In the tea industry, high-temperature reheating treatment is considered an effective measure to enhance the aroma of tea leaves. Through the study of the formation and changes of aroma components during the process of green tea re heating, it was found that after re heating, in addition to the formation of pyrrole, pyrazine, and furan substances, green tea also forms 3,7-dimethyl-1,5,7-trioctenol and phenylacetaldehyde. Among them, methyl pyrazine, 2,5-dimethylpyrazine, 1-ethylpyrrole-2-aldehyde, 2-acetylpyrrole, and sugar aldehydes were mainly generated. A small amount of these compounds can significantly improve the aroma of green tea. 5. Add aroma additives
In order to make up for the loss of aroma in the processing of tea drinks, instant tea powder or tea concentrated juice, the method of adding essence, spices or flavor improvement additives, such as β - cyclodextrin, can make up for or reduce the loss of aroma in the processing of tea drinks to a certain extent. 6. ARS aroma improvement technology
The principle of "ARS" technology is to avoid the loss of the light aroma or special head aroma of tea varieties during the production process. Firstly, during tea extraction, a special aroma extraction device (ARS) is used to continuously separate and extract aroma compounds from the tea slurry composed of tea and water. The extracted tea aromatic substances are condensed and refrigerated to maintain the best aroma quality. After extracting the aroma, the tea slurry and tea water can be further separated, filtered, and concentrated into concentrated tea juice using conventional techniques. Then, the extracted tea aroma liquid can be added back by the following method: adding a mixture again to the tea concentrate juice, and then producing the tea concentrate juice through UHT and sterile filling; Re add and mix in the concentrated tea juice, and then spray dry or freeze dry to produce high aroma instant tea powder; Adding tea powder during the mixing process to produce high aroma instant tea powder; Adding it as a natural flavor enhancer in the production of tea beverages to produce high aroma tea beverages. The ARS technology is used to produce the aroma of tea extract through tea pulp processing, similar to the aroma of freshly brewed tea. A comparison was made between the tea extracts obtained using conventional extraction equipment and ARS technology using GC analysis instruments. The results showed that the tea extracts obtained using ARS technology had a higher content (concentration) of aromatic substances (especially head fragrance). When the aroma liquid is added back to the tea concentrated juice, the flavored concentrated juice is added, and then UHT sterilization and aseptic filling are used to make the tea concentrated juice, or spray drying is used to make instant tea. The product shows excellent fresh, delicate or floral aroma characteristics. Especially in tea concentrate products, the performance is particularly outstanding, which can maintain 85% to 90% of the aroma characteristics and intensity of tea.
Shaanxi Huike Botanical Development Co., Ltd. a integrated enterprise which is focus on natural products, plant extract related products and services.We mainly focus on pharmaceutical, functional food, Freeze-dried powder,Natural Pigment,Homology of medicine and food,beverages and other business services.
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2024-06-12
Shaanxi Huike Botanical Development Co., Ltd.
