Tea contains ascorbic acid, tea tannin, theanine, aromatic oil, protein, catechuic acid, lipids, vitamins, pigments, pectin, enzymes and minerals. These components are easily affected by humidity, oxygen, temperature, light and environmental odor. Therefore, when packaging tea, the influence of the above factors should be weakened or prevented. The specific requirements are as follows.
1. 1 moistureproof
The water content in tea is the medium of biochemical changes in tea, and low water content is beneficial to the preservation of tea quality. The water content of tea should not exceed 5%, and 3% is the best for long-term storage, otherwise the ascorbic acid in tea is easy to decompose, and the color, fragrance and taste of tea will change, especially when the temperature is higher, the deterioration speed will be accelerated. Therefore, moisture-proof packaging can choose a composite film with good moisture-proof performance, such as aluminum foil or aluminum foil evaporation film as packaging materials.
1.2 oxidation protection
Excessive oxygen content in packaging will lead to oxidative deterioration of some components in tea. For example, ascorbic acid is easily oxidized to deoxyascorbic acid, which will further combine with amino acids to produce pigment reaction, which will worsen the taste of tea. Therefore, the oxygen content in tea packaging must be effectively controlled below 65438 0%. In packaging technology, inflatable packaging or vacuum packaging can be used to reduce the existence of oxygen. Vacuum packaging technology is a kind of packaging method that tea leaves are put into a soft film packaging bag with good air tightness, and the air in the bag is removed during the packaging process to produce a certain vacuum, and then sealed; Inflatable packaging technology is to fill in inert gas such as nitrogen while exhausting air, in order to protect the color, aroma and taste of tea and maintain its original quality.
1.3 high temperature protection
Temperature is an important factor affecting the change of tea quality. The temperature difference is 65438 00℃, and the chemical reaction rate is 3 ~ 5 times different. At high temperature, tea will aggravate the oxidation of the substances contained, leading to the rapid reduction of effective substances such as polyphenols and accelerate the deterioration of quality. According to practice, the optimum storage temperature of tea is below 5℃. When the temperature was 10 ~ 15℃, the color of tea decreased slowly, which could keep the color effect well. When the temperature exceeds 25℃, the color of tea will change rapidly. Therefore, tea is suitable for low temperature storage.
1.4 shading
Light can promote the oxidation of chlorophyll, lipid and other substances in tea, increase the odor substances such as valeraldehyde and propionaldehyde in tea, and accelerate the aging of tea. Therefore, tea packaging must be shaded to prevent the photocatalytic reaction of chlorophyll, lipids and other components. In addition, ultraviolet rays are also an important factor leading to the deterioration of tea. Shading packaging technology can be used to solve this kind of problem.
1.5 gas resistance
The aroma of tea is easy to be lost and influenced by external odor, especially the residual solvent of composite film and the smell of decomposition by electric hot sealing will affect the flavor of tea, thus affecting the aroma of tea. Therefore, when packaging tea, it is necessary to avoid the fragrance escaping from the packaging and absorb the external odor. Tea packaging materials must have certain gas barrier properties.
2, the packaging method of tea
As a special commodity, tea packaging is different from other general commodities due to its own and objective conditions. At present, the commonly used tea packaging methods mainly include the following.
2. 1 metal can packaging
Metal can packaging has excellent anti-breakage, moisture-proof and sealing properties, and is an ideal packaging for tea. Metal cans are usually made of tinned steel plates. There are square and cylindrical cans, and there are two kinds of single-layer lids and double-layer lids. From the point of view of sealing, there are two kinds of cans: ordinary cans and sealed cans. In packaging technology, cans can be packaged with deoxidizer to remove oxygen in the package. Sealed cans are mostly air-filled vacuum packaging. Metal cans have a better protective effect on tea than composite films, and their appearance is beautiful and noble. Their disadvantages are high packaging cost, high weight ratio between packaging and goods, and increased transportation cost. The well-designed metal cans are suitable for the packaging of high-grade tea.
2.2 carton packaging
Cartons are made of white board paper, gray board paper, etc., and are formed after printing. Carton packaging prevents easy damage and has excellent shading performance. In order to solve the volatilization of tea aroma in carton packaging and avoid the influence of external odor, tea is usually packed in polyethylene plastic bags and then packed in cartons. The disadvantage of carton packaging is that it is easy to get wet. In recent years, paper-plastic composite packaging boxes have appeared, which overcomes the problem that cartons are prone to moisture. The packaging box made of cardboard with plastic film layer or moisture-proof coating as packaging material not only has the function of composite film bag packaging, but also has the protection and rigidity of carton packaging. If plastic bags are used as small packaging bags, the protection effect will be better.
2.3 Plastic molding container packaging
Plastic containers such as polyethylene, polypropylene and polyvinyl chloride have the characteristics of elegance, beauty and good packaging and display effect, but their sealing performance is poor, so they are mostly used as outer packaging in tea packaging, and their packaging is mostly packed in composite plastic bags.
2.4 Composite film bag packaging
Plastic composite film has many advantages such as light weight, not easy to be damaged, good heat sealing, reasonable price and so on, and is widely used in packaging. There are many kinds of composite films for tea packaging, such as moisture-proof cellophane/polyethylene/paper/aluminum foil/polyethylene, biaxially stretched polypropylene/aluminum foil/polyethylene, polyethylene/polyvinylidene chloride/polyethylene and so on. The composite film has excellent gas barrier, moisture resistance, fragrance retention and odor resistance. Because the light transmittance of most plastic films is 80% ~ 90%, in order to reduce the light transmittance, ultraviolet suppression can be added to packaging materials or printing coloring can be used to reduce the light transmittance. In addition, composite materials based on aluminum foil or vacuum aluminized film can be used for shading packaging. There are many packaging forms of composite film bags, such as three-sided sealing shape, self-standing bag shape, folding shape and so on. As the composite film bag has good printability, it plays a unique role in attracting customers and promoting tea sales as a sales packaging design.
2.5 paper bag packaging
Tea bag, also known as tea bag, is a kind of bag packaging with thin filter paper as the village material, which is put into the tea set together with the paper bag when used. The main purpose of packaging with filter paper bag is to improve the leaching rate, and also to make full use of tea powder in tea factory. Teabag is very popular in the international market because of its advantages of rapid brewing, cleanliness, standard dosage, mixed drinking, convenient slag discharge and portability, which meets the needs of modern people's fast-paced life. Early teabags generally had bag lines to meet the convenience of repeated soaking. Due to the requirements of environmental protection, teabags without bag thread are gradually becoming popular.