UDC 338.24
TASTING AS THE MAIN METHOD OF ORGANOLEPTIC ASSESSMENT OF TEA QUALITY
Kovalenko Tatyana Dmitrievna Penza State Technological Academy
Penza, Russia
Tasting as the main method of organoleptic evaluation complements the objective methods of tea quality control. Organoleptic indicators of tea quality include: appearance, brightness and intensity of the infusion, taste and aroma, color of the boiled leaf. Infusion, aroma, taste and color of the boiled leaf is determined after brewing tea. Processing the results of tasting includes the calculation of the arithmetic mean of the indicators, standard deviation and complex indicators of tea quality, taking into account weight coefficients. According to the results of the organoleptic evaluation of the quality of the samples, it is possible to draw conclusions about the quality of tea.
Tasting; organoleptic quality indicators; falsification; average sample; hitch; quality categories
Tasting; organoleptic quality indicators; falsification; average test; a hinge plate; quality categories
The main method for assessing the quality of tea remains organoleptic, that is, tea tasting. Tasting does not exclude, but complements the objective methods of tea quality control. Although the subjective factor is present, it is not decisive; therefore, the tasting method is quite suitable not only for assessing the quality of various batches of industrial products, but also in scientific research. To improve the accuracy of tea assessment, each sample is offered to be tested by a group of tasters, and the resulting scores are averaged.
Organoleptic indicators of tea quality include: appearance, brightness and intensity of the infusion, taste and aroma, color of the boiled leaf. In appearance (cleaning) ready green tea is a smooth, uniformly twisted, different in size (depending on the kind of leaf) tea leaves. It has a delicate, delicate, characteristic of green tea, pleasant, with astringency taste. Its infusion is clear, lemon-colored. The color of the boiled leaf is uniform, with an olive greenish tint.
For analysis, a sample weighing 100 g was taken from the average sample and poured out in a thin layer on a sheet of white paper. The appearance of tea was determined by inspection in daylight diffused light or bright artificial light. At the same time, attention was paid to the color, evenness, uniformity and degree of twisting of the tea leaves. The presence of petioles (red stems) or wood fibers in tea indicates that the tea is made from coarse raw materials and is poorly sorted.
The infusion, aroma, taste and color of the boiled leaf were determined after brewing the tea. To do this, we weighed a 3 g portion of tea on a technical scale and poured it into a titestor porcelain teapot with a capacity of 125 cm 3, after which it was poured with boiling water, without adding 4-6 mm to the top of the teapot, and quickly closed with a lid, after 1-1.5 minutes . began to determine the aroma. To determine the taste of the infusion, they drank some tea from a cup and, without swallowing, rolled it in the mouth, evaluating the taste sensations. The astringency and fullness of the taste of the infusion is a sign of extractiveness and high P-vitamin activity of tea. With insufficiently pronounced astringency, tea has an empty taste. An infusion devoid of astringency is considered “watery” (low content of extractives in raw materials, weak twisting of leaves, absorption of excess moisture by tea). In the course of the study, we used a special tea utensil - gaiwan (porcelain, made in China, volume 125 ml.) and a tea tool.
Chaow or gaiwan is a miniature tea brewing set. Includes cup, lid and saucer. Chaow brewing is used when you need to taste tea, as well as for everyday tea drinking. A handy item for quick tea brewing. This is an opportunity to look at the brewing tea leaves and smell them. Any tea can be brewed in chaow. Gaiwan brewing rules:
Heat the chow with boiling water.
Pour the tea leaves into the chaow.
Rinse the tea leaves and drain immediately.
Pour 2/3 of the water down the side of the cup.
Wait 30 seconds, pour tea.
Serve tea.
For various actions with tea during tea drinking, various tea devices have been used since ancient times. All of them are called chaju. The metamorphoses of time have influenced the variety of forms of the tea instrument. The composition of the set of tools also changed at different times, but at the moment the most common set has developed, which we describe. The spoon is used to transfer tea from the caddy (Cha Yeguan) to Cha He. The needle (Cha Zan) is a wooden needle with a plastic or bone tip. It is commonly used to clean out stuck tea leaves in a teapot. However, it must be remembered that the needle is used only in those teapots that do not have a mesh inside, or this mesh consists of large holes. An attempt to apply a needle to teapots of modern designs, with careless movements, can lead to its damage. In some sets, the needle and spatula are combined - on one side the needle, on the other hand the spatula. A funnel (Cha Xiangluo) is used to prevent tea from waking up past a small teapot. Tongs (Jiazi) are designed to take hot cups for rinsing them, to get the tea leaves asleep.
The simplest methods for processing the results of tasting with a small number of experts (7 people) included the calculation of the arithmetic mean of the indicators, the standard deviation and complex indicators of tea quality, taking into account weight coefficients. Green tea quality categories are presented in Table 1.
Inferior 1-2
Below average 2.5-3
Average 3.25-4
Good average 4.25-5
Good 4.75-5
Above good 5.26-6
Supreme 6.28-8
First, the assessments of experts, who were tasters, were averaged by single indicators, they were entered into the summary sheets for each sample, and the arithmetic mean value of the assessments of individual indicators (in points) was calculated using the formula
where I x - the sum of the tasters' ratings for a specific indicator (aroma and
taste, infusion, etc.) of one tea sample, points; n is the number of tasters.
To characterize the spread of the totality of tasters' assessments, the standard deviation for each single indicator was determined using the formula:
where I xr2 is the sum of the squares of the tasters' ratings, points;
x2 is the square of the average value of the indicator scores, points.
The standard deviation S characterizes the consistency of expert opinions under the condition of homogeneity of the analyzed samples. The scores are unambiguous, S on a 10-point scale does not exceed ± 1 point. The results of testing the scoring scale are shown in Table 2.
table 2
Tasting sheet of the organoleptic evaluation of the quality of green tea
№ Indicator Ko Numerical Characteristics of quality levels
n/ and quality ef value of green tea
n fi levels,
t weight ohm axle
1 Aroma and taste 0.3 5 9-10 7-8 6 5 4 3 2 1 Sufficiently full bouquet, very thin delicate aroma, spicy taste pleasant with astringency Full bouquet, delicate, delicate aroma, pleasant taste with astringency Delicate aroma, pleasant with astringency taste Pleasant aroma and rather tart taste Pleasant aroma and tart taste Weak aroma, insufficiently tart taste Very weak aroma, insufficiently tart taste Rough aroma, slightly perceptible tart taste
2 Infusion 0.2 9 - 10 7 - 8 6 5 4 3 2 1 Transparent, olive, with a yellowish tint Transparent, light green, with a yellowish tint Transparent, light green with a yellowish tint Transparent, light yellow Transparent, light yellow with a pink tint Yellow with a reddish tint, not transparent Yellow with a red tint, not transparent Dark yellow with a reddish tint, cloudy
3 Color of the boiled leaf 0.1 5 9 - 10 7 - 8 6 5 4 3 2 1 Fairly uniform, with a greenish tint Uniform, with a greenish tint Uniform, with a greenish tint Insufficiently uniform, with a yellowish tint Insufficiently uniform, with a light yellow tint Heterogeneous , with a yellowish tinge Non-uniform, yellow Non-uniform, dark yellow
4 External 0.3 9 - 10 Fairly even, uniform, good
twisted view
(cleaning) 7 - 8 Smooth, uniform, well curled
6 Smooth, uniform, twisted (sheet); medium leaf - even, twisted, with the presence of lamellar
5 Not flat enough, twisted
(sheet); medium leaf -
not even enough
twisted or lamellar
4 Not flat enough, twisted
3 Uneven, insufficiently twisted
2 Uneven, badly twisted
1 Uneven, the tea leaves are very badly twisted
The results of the organoleptic evaluation of the quality of samples of green Chinese
tea was arranged in table 3.
Table 3
Organoleptic evaluation of the quality of green tea samples
Sample number, name Quality indicators Weighting factor Numerical value of levels, points (average score) Generalized quality index, points Quality categories, variety
1 "Kudin Aroma and taste 0.35 1.1
middle leaf Infusion 0.20 1.0 1.76 lower
ready" Color of boiled 0.15 2.0
Appearance 0.30 2.9
2 Aroma and taste 0.35 2.0
«Green Infusion 0.20 5.1 3.12 medium
pearls Boiled color 0.15 3.3
Appearance 0.30 3.0
3 Aroma and taste 0.35 2.1
«Green Infusion 0.20 5.0 3.50 medium
leaf Color of boiled 0.15 5.0
Appearance 0.30 3.3
4 Aroma and taste 0.35 1.7
"Beauty's eyelashes" Infusion Boiled leaf color Appearance (cleaning) 0.2 0.15 0.30 5.1 3.0 2.3 2.76 below average
5 "Gunpowder Aroma and taste 0.35 2.4
weakly infused Infusion 0.20 5.3 3.52 medium
cooked» Color of boiled 0.15 4.0
Appearance 0.30 3.4
6 "Gunpowder Aroma and taste 0.35 4.0
silver Infusion 0.20 5.0 4.14 medium
th» Color of boiled 0.15 3.4
Appearance 0.30 4.1
7 Aroma and taste 0.35 2.4
«Ganpaud Infusion 0.2 5.0 4.21 medium
ep" Boiled color 0.15 4.4
Appearance 0.30 5.7
8 Aroma and taste 0.35 5.4
«Green Infusion 0.20 5.1 4.94 good
spirals» Boiled color 0.15 3.6 medium
Appearance 0.30 5.0
9 Aroma and taste 0.35 6.0
"Spiral Infusion 0.20 4.0 5.30 above
Jade" Boiled color 0.15 6.0 good
Appearance 0.30 5.1
10 "White Aroma and taste 0.35 5.0
monkey Infusion 0.20 5.6 4.60 good
Boiled color 0.15 3.7 medium
Appearance 0.30 3.9
11 Aroma and taste 0.35 5.0
"Green Infusion 0.20 4.9 5.22 above
Yunnan Color boiled 0.15 6.6 good
Appearance 0.30 5.0
12 "Temple Aroma and taste 0.35 1.4
sky" Infusion Boiled leaf color Appearance (cleaning) 0.20 0.15 0.30 5.0 3.7 5.4 3.67 medium
13 Aroma and taste 0.35 3.6
"Nine Infusion 0.20 5.0 4.50 good
dragons Boiled color 0.15 4.1 medium
Appearance 0.30 5.4
14 Aroma and taste 0.35 1.7
"Kudin" Infusion 0.20 2.0 2.17 lowest
Boiled color 0.15 2.0
Appearance 0.30 2.9
Samples No. 9; 11 have a quality above good, which corresponds to the Russian counterpart as the highest grade.
Samples No. 8; ten; 13 have a good average quality, which corresponds to the Russian analogue as the first grade of I and II categories.
Samples No. 2; 3; 5; 6; 7; 12; have an average quality, which corresponds to the Russian analogue of the second grade.
Sample No. 4 has a quality below average, which corresponds to the Russian counterpart as the second grade III category.
It is known that obtaining a red leaf color in the production of green tea is undesirable. This may be due to incomplete inactivation of the enzyme complex, which results in the oxidation of tannins, and is also associated with a violation of the duration of heat treatment of green tea leaves with a high moisture content, which leads to a decrease in the aromatic and taste characteristics of the finished tea, and an increase in its color; as a result, the infusion of some tea samples had a pink tint (for example, sample No. 9).
Samples No. 1; 14 have the lowest quality, which corresponds to the Russian counterpart as the third grade. Such a low quality of green tea samples can be explained by two reasons: high-quality falsification; long shelf life, as a result of the aging process during the oxidation of tea leaf substances.
Bibliographic list
1. GOST 3716-90. Bulk green tea. Specifications.
2. GOST 1936-85. Tea. Acceptance rules and methods of analysis.
3. Elizarova L.G. Examination of the quality of tea. - M.: Moscow Higher School of Expertise, 2001. - 43 p.
4. Rodina T.G. Sensory analysis of food products. - M.: ACADEMA, 2004. - 208 p.
5. Khoperia R.M. Tea production technology. - M.: Agropromizdat, 1988. - 160 p.
Municipal educational institution
"Bakchar Secondary School"
STUDY OF ORGANOLEPTIC AND CHEMICAL INDICATORS OF BLACK AND GREEN TEA
Design and research work
MBOU "Bakcharskaya secondary school", grade 11
Head: Zaitseva Lyubov Valentinovna,
Chemistry teacher.
Bakchar village - 2016
Table of contents
1. Introduction ……………………………………………………………………… 1 page
1.1 Relevance…………………………………………… 1 page
1.2. Purpose……………………………………………………… 1 p.
1.3.Tasks…………………………………………………… 1 page
1.4.Questioning ………………………………………… 2 p.
2. The history of tea…………………………………………….. 4 p.
2.1. Tea in China………………………………………………4 pages
2.2. Tea in Russia………………………………………………… 5 pp.
3. The chemical composition of tea,…..………………………………………………… 7 p.
4. Stages of tea production………………………………………………………………………………………………………………………………………………….
5. Varieties and grades of tea……………………………………………….. 10 p.
6. Extraordinary facts about tea……………………………………………….. 14 p.
8. Conclusion…………………………………………………………………… 19 p. 9. Sources and literature……………………………………… ……………… 20 pages
10. Application. The study of tea ………………………………………. 21 pages
10.1. The mechanical composition of tea. ……………………………….. 21 pages
11.2 Determination of the presence of dyes………………………… 22 p.
11.3 Organoleptic properties of tea ………………………… 23 p.
11.4. Determination of acid-base balance……………… 23 pp.
11.5. Determination of tannin in tea…………………………………… 24 pages
11.6. Qualitative response to caffeine…………………………… 24 pp.
1. Introduction.
1.1. Relevance.
The usual means to disperse melancholy and unite the family.All over the world people know and love tea as a beverage. We have seen how it is prepared more than once: dry leaves are poured with boiling water. But what is this plant - tea?We rarely ask ourselves what this "good friend" tea contains and how one type differs from another.Where does it grow? What are its properties? How is it used? It became interesting to me. I tried to answer these questions in my work.Nowadays, the market offers tea of different quality and price, it is important to be able to understandm and correlate quality with price,be able to chooseandarmy correctly. In the process of research, a familiar drink reveals many of its secrets.
Separate fragments are visible, the surface of which is covered with hairs.
The particles are dark brown in color, have the same, small size. There are also light brown inclusions.
Parts of leaves and stems. The structure is homogeneous. The color of the particles is from light brown to dark brown.
The particles are different in size and shape, the main mass is dark brown, contains inclusions of light brown. Particle sizes from 1 mm to 6-7 mm.
Parts of leaves and stems. The structure is homogeneous. Dark brown.
Small in size, dried, twisted parts of the leaves. The shape and size of the leaves are different. Color from light green to dark green, available in a small amount particles of yellow stems.
Parts of leaves and stems The structure is homogeneous, without fibers, dark green.
Conclusion: As a result of examining the contents of tea with the naked eye and under a microscope, it was revealed that heterogeneity is determined in samples No. 1, 3.4. When studying the mechanical composition under a microscope, it was revealed that in sample No. 4 there are parts of the leaves and a lot of parts of the stem. In the sample under No. 1, separate fragments are visible, the surface of which is covered with hairs, which, in my opinion, are not related to tea. In samples under No. 2,3, the contents and particle sizes are almost the same. In the sample under No. 4, the surface of the leaves is shiny and matte.
Examination of the presence of dyes.
Method: Brew tea with water room temperature and we insist 7-10 minutes and we see that the color intensity is more pronounced in samples under No. 2.3.
Method: Place a fabric in the prepared warm infusion of tea white color for 7-10 minutes, then dry and see the difference in color.
Conclusion: Pigmenting and coloring substances contained in tea leaves can be used as safe dyes.
In the resulting tea infusions, add a slice of lemon. The lemon reacted with the coloring substances of the tea, resulting in a discoloration of the solutions compared to the original color. This indicates that dye was added to these samples, and in a larger amount in samples No. 2,3.
Study of the organoleptic properties of tea.Determination of taste and aroma.
Methodology: tea is brewed for 5-7 minutes, then the aroma of tea in pairs, taste characteristics, degree of astringency and the presence of foreign flavors are compared.
Table number 2.
p/n
Name of tea
Aroma in pairs
Taste
Degree of astringency
Foreign taste
"Princess Java" green tea with jasmine. Packaged.
Weak, sweetish, with jasmine aroma
Weak bitterness
Weak
Grassy
"Princess Nuri" high-mountain, black, long leaf tea. Packaged.
Medium, sweetish
Medium bitterness
Medium
Not
"Princess Nuri" high-mountain, long leaf, black tea. Leafy, small.
Average,
sweetish
Medium bitterness
Medium
Not
"Princess Java" Chinese, green, long leaf tea. Sheet.
Weak
Weak bitterness
Weak
Grassy
Conclusion: The aroma of tea in pairs is weak in samples No. 1.4. The smell is sweetish in samples No. 1,2,3.
Weak bitterness is noted in samples No. 1.4, medium - in samples No. 2.3. The degree of astringency is more pronounced in samples No. 2,3. The grassy taste is more felt in samples No. 1.4.
Determination of acid-base balance.
Methodology: In the resulting tea infusion, strips of indicator paper were placed to determine the pH, and then compared with the standard.
Conclusion: Green tea has a pH of 6, while black tea has a pH of 5. The solution medium is close to neutral.
Determination of tannin in tea.
Method: Add 5-6 drops of ferric chloride (3) to the tea solution. In the presence of tannin in tea, the appearance of a dark purple color was observed.
Conclusion: In the samples under No. 3 and No. 4, the highest content of tannin.L-tanninis a water-soluble chemical found in tea and is responsible for some of the effects that tea has on the human body and condition, as well as affecting the taste and aroma of tea. It is an amino acid derivative of glutamic acid.
Definition of caffeine.
Method: Place 0.1 tea in a porcelain cup, add 1-3 drops of concentrated nitric acid. The mixture is carefully evaporated to dryness. As a result of the oxidation of caffeine, orange-colored tetramethylaloxanthine is formed. The analysis data are compared with the standard obtained from a citramone tablet containing 43% caffeine.
Conclusion: There is more caffeine in samples No. 1.4. Green tea contains more caffeine than black tea. Alkaloids are an important component of any tea. It is in this group of substances that caffeine, or tea theine, is included. It is caffeine that has a tonic, stimulating effect on a person. The caffeine content in tea is higher than in coffee. In addition, tea caffeine is more beneficial for the human body. Caffeine is found in tea leaves, and in the leaves that appeared first, its content is higher.
Table number 3.
p/n
Name of tea
pH
Presence of tannin content
Vitamin C content.
Sample #1
Average
0,00009
Sample #2
high
Sample #3
high
0,00013
Sample #4
average
22 +1,8
Table #3
Conclusion: Based on the conducted research, the following conclusions can be drawn:
According to the mechanical composition, only sample No. 2 corresponds to the GOST standards, because according to the regulations, there should be no stem in tea leaves. The external inhomogeneity of the composition is determined for samples No. 1,3,4.
The solution medium is close to neutral. Green tea has a slightly higher pH of 6, while black tea has a pH of 5.
All tea samples contain artificial coloring,which is unacceptable, according to GOST.
Tannin is found most in loose leaf tea compared to tea bags.
Caffeine is found in all tea samples. It is found in large quantities in green leaves.
The aroma, astringency, taste of tea correspond to the traditions of tea drinking in all samples.
The information indicated on the tea packages is often incomplete, there is no description of the processing of tea, no specified time of collection, no place where the tea grew.
Thus, all the studied teas comply with the GOST standards and can be recommended for use.
The analysis was carried out for compliance of the labeling of tea samples, label design, packaging condition, with the requirements of GOST R 51074-2003 Food products. Information for consumers. General requirements, GOST 1938-90 Packed black tea. Specifications, TU 9191-001-56843012-03 and made conclusions about compliance with the requirements specified in the regulatory documents.
From the organoleptic quality indicators in tea, the following were determined: appearance (cleaning), color of the infusion, taste and aroma, color of the boiled leaf in the following sequence. First, visually studied the appearance, then brewed a portion of tea and determined the color of the infusion, its aroma and taste. The aroma of tea is better felt in the pairs of boiling. The color of the boiled leaf was studied after putting it on the lid of the teapot.
Long leaf tea of good quality should consist of homogeneous, well-rolled tea leaves, of the same size, without wood hairs, red petioles, yellow or green dust; Bouquet tea should contain golden tips.
Preparation of infusion and evaluation of its quality.
Preparation for analysis. A sample weighing 100 g was taken from the average sample and 3 g of tea was taken from it, placed in a special porcelain teapot, poured with boiling water in an amount of 125 ml, and closed with a lid. After 5 minutes, the infusion from the teapot was poured into a special porcelain cup, the teapot was shaken several times so that the last purest drops of the infusion completely drained.
The analysis of tea was carried out 1-1.5 minutes after the infusion was poured into a cup.
Analysis.
The color intensity, shade and transparency (purity) of the infusion were determined visually.
The aroma was determined in the pairs of tea boiling. At the same time, extraneous odors and defects not characteristic of tea were detected. Then the taste of tea was determined, noting the fullness, degree of expression and its astringency, as well as extraneous flavors that are not characteristic of tea. The color of the boiled leaf was determined after laying it on the lid of the teapot.
Infusion color.
The color of tea infusion is: weak, intense, cloudy. The infusion should be transparent, clean, copper-red shades.
A brown infusion or cloudy infusion gives an over-fermented tea.
The dark color of the infusion indicates prolonged fermentation.
The greenish color of the infusion is characteristic of underfermented tea.
Aroma of infusion.
The specific aroma of black long leaf tea is due to the content of essential oils in it, which are mainly formed as a result of oxidative processes during fermentation. The aroma of tea should be delicate, subtle, floral, honey, etc.
Disadvantages of the aroma of black long leaf tea: sour, burnt, (hot), green smell, musty, smoky, etc.
Sour smell - occurs as a result of overfermentation of raw materials, as well as in violation of drying regimes or damage to the sheet during transportation.
Burnt smell (hotness) - in case of violation of the drying process.
The smell of greenery is underfermented tea. Violation of the process of withering, twisting, fermentation.
Musty (damp smell) - occurs due to the aging of tea under the influence of microorganisms during storage in conditions of high relative humidity or if the leaf is damaged by microorganisms before processing.
The taste of tea.
Determined correct throughout the text of the ending "from the first person" determined, looked, poured, measured, etc. along with the aroma of the infusion. The leading role in the formation of taste belongs to tannins (tea tannin). The tannins of tea are polyphenols of organic compounds, a complex complex of catechins and their derivatives.
During fermentation, due to the oxidation of catechins, the bitter taste disappears and astringency appears.
Good quality tea should have a full taste with astringency (the so-called "body" of tea). Tea that lacks flavor is said to be "watery" or "empty".
The “empty” taste is the result of over-fermentation.
"Greens" - a bitter taste without astringency, combined with a "green" aroma, occurs with insufficient fermentation.
Broken leaf color.
The color of the boiled leaf indicates the observance or violation of the technological regimes for processing the tea leaf.
The color of the boiled sheet should be even, light brown.
Flaws.
Dark color is observed with excessive fermentation or excessive wilting.
Variegated color - when processing underfermented raw materials.
When characterizing appearance natural roasted coffee beans pay attention to the uniformity and uniformity of roasting beans. Ground coffee should be a brown powder with the inclusion of coffee bean shells.
The taste of coffee is evaluated only in the extract after brewing. The aroma of coffee is determined in the dry product and in the extract.
For determining taste coffee extract is drunk in small sips and the first taste sensations are recorded. The taste of coffee is characterized by the following terms: empty, grassy, astringent, bitter, velvety, winey, full, pleasant, delicate, sharp, rough, etc.
For rate flavor coffee extract is brought to the nose and inhaled. Good coffee has a delicate aroma characteristic of normally roasted beans.
Results
The results of the organoleptic evaluation of coffee quality are listed in Table. 12.2.
Table 12.2
Organoleptic characteristics of coffee
Students need to familiarize themselves with the presented theoretical material; determine the quality of various types of tea and coffee by organoleptic indicators. Prepare a report indicating the purpose of the work, the main theoretical provisions, as well as a description of the sequence of work; answer the control questions in writing. Print and submit GOSTs regulating the organoleptic quality indicators of coffee and tea.
test questions
What is the value of tea?
What types and types of tea are distinguished?
What is the value of coffee?
What types of natural coffee are there?
By what indicators is the organoleptic evaluation of tea made?
What are the criteria for organoleptic evaluation of coffee?
What indicators refer to the physical and chemical indicators of the quality of tea?
Name the physical and chemical indicators of coffee quality.
What are the microbiological and safety indicators of tea and coffee?
According to what GOST is the quality of tea assessed?
According to what GOST is the quality of coffee assessed?
List of used literature
Mikulovich L.S., Smolskaya A.O. Merchandising of food products. Textbook. 5th edition, add. and Perer. - Rostov n / a: "Phoenix", JSC "Moscow Textbooks", 2005. - 596 p.
Gavrilova N.B. , Shchetinin M.P. Laboratory workshop on the technology of milk and dairy products: Textbook. - Barnaul - Omsk: AltGTU Publishing House, 2003. - 159p.
Vinogradova A.A., Melkina G.M., Fomicheva L.A. and others. Laboratory workshop on the general technology of food production. / Ed. L.P. Kovalskoy.- M.: Agropromizdat, 1991.
Shildlovskaya V.P. Organoleptic properties of milk and dairy products. Directory. M.: Kolos, 2000. - 280s.
Nikolaeva M.A., Polozhishnikova M.A. Identification and detection of falsification of food products. Tutorial. - M .: ID "FORUM": INFRA-M, 2009. - 464 p.: ill.
Reference book of the commodity specialist of food products: in 2 volumes / B.V. Andret, I.A. Bolkind, V.Z. Gornitskov et al. - 2nd ed., revised and additional. – M.: Economics, 1987. – 386 p.
Kastornykh M.S., Kuzmina V.A., Puchkova Yu.S. Commodity science and examination of food fats, milk and dairy products / Textbook for higher educational institutions. M.: Publishing Center "Academy", 2003. - 288 p.
General technology of food production. / Ed. L.P. Kovalskaya. - M: Kolos, 1997. - 752 p.
Chepurnoy I.P. Commodity research and examination of taste products. M.: Dashkov i K, 2005. - 404 p.
Nilova L.P. Commodity research and examination of grain flour products. Textbook - St. Petersburg: GIORD, 2005. - 416 p.
Blinnikova O.M. Commodity research and examination of food products. Dietary fats. Training and metodology complex. Michurinsk: MichGAU Publishing House, 2008. -87 p.
Currently for tea quality ratings Increasingly, various objective methods (chemical, physical, biochemical) are used, which are carried out at the end of each production process on the basis of the characteristic physico-chemical changes inherent in this stage of tea leaf processing. Biochemical analysis allows you to establish the composition of tea. More acceptable in this regard are such physical and chemical methods of tea analysis as the refractometric method for the quantitative determination of extractive substances, the spectrophotometric method for determining caffeine in tea, and others, which allow using instruments to determine substances and their properties in tea infusion. However, according to their results, it is impossible to assess the quality of tea as a whole.
The researchers tried to establish a relationship between the quality of tea and its chemical composition. Some scientists believed that the main substance that determines the quality of tea is caffeine, others preferred its phenolic compounds, believing that the more of them contained in tea, the better its quality. But practice has shown that one definition of the quantitative composition chemical substances tea, it is impossible to accurately determine the quality of the finished product.
Indian teas are a prime example of this. If we compare Assam tea with Darjeeling, then although Assam tea contains much more tannin, it is inferior to Darjeeling in quality: Assam tea is more tart, but less fragrant, and Darjeeling has a rather tart taste and a delicate aroma. In this regard, we present a witty comparison of Ribero-Gayon's assessment of the importance of the chemical method. He says that modern methods of chemical analysis are very similar to those that would try to determine the structure of a house by destroying it, separating the different materials and weighing them: this would reveal what the house was built of, but would not give any idea of \u200b\u200bthe plan of its construction , the location of various parts and their sizes, the way materials are assembled into a single whole. Meanwhile, the importance of objective methods for evaluating tea is undoubtedly important, since physical chemistry makes it possible to judge the relationship between the various components of tea, their proportions, and certain properties of it are determined with the help of special methods.
However, the oldest and at the same time the simplest, fastest and most reliable method for determining the quality of tea is tasting - tea-testing of the received batches of tea. Tasting is a quality assessment method food product, which is carried out with the help of the senses without the use of special devices or chemical analyzes. Unlike biochemical control, which can be carried out at different stages of tea production and requires complex technical equipment, this method evaluates the finished product at the stage of a semi-finished or finished product, does not require complex technical means and a large staff of workers.
Tasting is the most reliable method for accurately determining the quality of tea. Despite the subjectivity of the method, it is of great importance for the rapid recognition of the quality of tea, since some properties of tea (shades of smells, smokiness, the presence of different flavors, and others) cannot be characterized without tea-testing. In addition, there are elements of objectivity in this method, since otherwise the assessments of the quality of tea made by different people would not coincide as it is observed in reality.
The tasting is done by a teatester (the English word teatester can be translated as "tasting tea") - a professional tea taster. The terms of reference of the teatesters are determined by the evaluation of the quality of the finished product. In addition, he is also responsible for the blending of the finished tea. The profession of a teatester is highly respected in the "tea" world, since it is he who determines the quality of a tea sample, giving each one points for the appearance, aroma, color and taste of the infusion. Sophisticated technique is not able to compare with his skill and knowledge. However, a tea taster is more than a profession. It is also a vocation, special abilities (delicious taste, perfect sense of smell), colossal self-discipline, unique experience and extensive knowledge.
Tea tasting is an organoleptic method for assessing the quality of finished products. The word "organoleptic" comes from two ancient Greek words: organon (organ, tool, tool) and leptikos (able to take, perceive). In the tea industry, the organoleptic evaluation method is the main method for determining the quality of tea, so the teatester who determines the variety and category of tea must have a high ability to distinguish all those quality indicators by which it can be determined whether the product being tested meets the requirements of the standards.
The perception of the sense organs is influenced by many factors: the purity and relative humidity of the air, the temperature of the sample and the environment, and the illumination of the room. So, best temperature air in the room where the organoleptic analysis (tasting) is performed is considered to be 20-24 ° C, and optimum temperature sample prepared for tasting - 80 C. It is desirable to maintain the relative humidity of the air, which contributes to a better perception of smell in the organoleptic analysis of tea, at a level of 60-70%. Experiments also proved that light sharpens the sense of smell and other senses, having a beneficial effect on the general condition of the central nervous system. In addition, in a bright room it is easier to maintain the quality of visual control. Therefore, tea tasting is carried out in a room specially designated for this purpose, in which there is enough light to better capture the differences in shades of tea infusion and boiled leaves when tasting tea, a certain temperature and humidity are maintained, and furnishings do not contain pungent odors so that the teatester can perceive subtle flavors and aromas.
The ability to perceive can also vary depending on the state of health, mood, degree of fatigue and attentiveness, personal hygiene. Therefore, the rules of tasting require that before it begins, tea-testers do not consume spicy, odorous and hot dishes, alcoholic beverages, do not use fragrant soap, perfume or cologne, avoid using any cosmetics, and also do not have colds, do not get nervous, do not get distracted.
In organoleptic analyses, an important role is undoubtedly played by the degree of teatester fatigue when testing tea samples. As a result of a nervous state, feeling unwell or evaluating an excessive number of samples, absent-mindedness may appear, sensitivity may decrease, a state of physiological fatigue of the sense organs (their adaptation) and mental inoperability may occur. It has been established that if, when determining the aroma, fatigue occurs after 100-125 samples, then when determining the taste, the sensation noticeably weakens after testing 50 samples, and after 70 samples it completely disappears. Therefore, in tester practice, there are also certain threshold norms for the number of samples (no more than 15-20 assessments are performed in a row).
Tasting order
The production equipment of the tea-testing laboratory is very simple: porcelain tasting cups, teapots with a capacity of up to 125 ml, pharmaceutical scales, a kettle for boiling water, a five-minute hourglass.
As a rule, samples submitted for evaluation are tested by three testers. Each teatester works independently. First, the cleaning (appearance) of tea is checked, then (by eye) - the degree of intensity of the infusion; after that, the sample is tested first for aroma, then for taste; the color of the boiled sheet is checked last.
The tasting procedure is strictly sequential. First, portions of 3 g of tea are weighed on accurate teatester scales, which are brewed for 5 minutes with fresh boiling water of a certain temperature in small porcelain teapots with a standard capacity of 125 ml. While the tea is infused, tea-testers study the contents of the packs - dry tea leaves. By appearance, you can determine the cleaning of dry tea particles (their size, uniformity, curl). Then the resulting infusion is poured into a cup so that boiled tea leaves do not get there. While the tea is cooling, tea-testers evaluate the intensity of the color of the infusion, its shades and transparency, as well as the aroma, which judges the tenderness of the bouquet (combination of taste and aroma), its fullness and strength. Then they taste the tea, and do not drink the infusion, but only slightly rinse their mouth with it. In the taste of tea, tea testers evaluate the "body" of the infusion (its extractiveness), astringency, character, lack of bitterness. In conclusion, the tea-testers check the "decoction" of tea - the appearance of the boiled leaf. After the end of the tasting, the sensations experienced during the tasting are discussed by all three tea-testers, after which a score in points is assigned to one or another tea sample. Usually, if one teatester's score differs from that of two others, then the grade and category are determined by the two teatesters giving the same score. But here it should be noted that such discrepancies in organoleptic analysis are rare, and in most cases all three tea testers give the same score, which is due to their great skill and training. If at least one of the members of the commission admits that the sample has signs of acidity, hotness, mustiness, bitterness or any other foreign smell, to whatever extent these shortcomings are found, the sample is brewed a second time. At the same time, dubious samples are brewed simultaneously with standard ones, tested in advance and recognized as completely clean. If the previously discovered deficiencies were confirmed during re-testing, then the product is rejected.
International Tea Quality Assessment System
A 10-point assessment of the quality of tea is accepted all over the world, where 0.25 points is a transitional step from one variety to another. Despite the same assessment system, the quality division of tea according to the Russian classification is fundamentally different from that used abroad. So, according to the international classification, long leaf tea is divided into five groups according to its dignity: high; superior; average; below average; short. There is tea of exceptionally high value, which does not belong to any of these groups. Such tea is called Unique - unique (incomparable, exceptional).
This division is somewhat arbitrary, since the assessment is based on the subjective method of organoleptic evaluation of tea quality. However, tea that has been assigned one or another quality category will always have a price corresponding to it.
Main indicators of tea quality
Determination of the quality and grade of tea is carried out by organoleptic analyzes according to five quality indicators:
- 1) appearance;
- 2) the intensity of the infusion;
- 3) aroma;
- 4) taste;
- 5) the color of the boiled leaf.
An unmistakable assessment of product quality depends on the correct definition of each of them.
Consider the significance of these qualitative indicators separately.
1. Appearance of dry tea leaf (tea harvesting). The appearance of tea gives an idea of what raw materials the products are made from, whether the technological regimes are observed, especially in the process of twisting and sorting tea. Cleaning of tea is determined by scattering it on white paper. When assessing the appearance of tea, the main attention is paid to the uniformity of the mass, the color of the tea leaves, the twisting of the leaves, the presence of golden tips, the presence of coarse stems, wood hairs, dust and other impurities.
Well-harvested teas consist of uniform, well-rolled tea leaves, with no admixture of teas of other sizes, and have the appropriate color for the type of tea, which indicates correct sorting.
The presence of golden tips indicates the preparation of tea from delicate raw materials, which are collected at a time when buds with silvery hairs appear on the tea leaves. With proper processing, these hairs (fluff) are covered with juice released from the cells of the tea leaf, and during the drying process they acquire a light golden color. Presence in tea a large number golden tips indicates the high virtues of tea.
The presence of petioles (red stems) or hairs of wood in the tea indicates that the tea is made from coarse raw materials (raw materials of late harvest) and is poorly sorted. The more petioles or hairs of wood the tea contains, the lower its quality.
The admixture of non-twisted leaf blades negatively affects the quality of tea. When processing coarse raw materials, the third leaf of the tea shoot does not roll well, juice is hardly squeezed out of its cells, therefore, untwisted tea plates contain less extractive substances, which has a very negative effect on the aroma and taste of tea.
2. The color of the tea infusion. Determined by its intensity and the nature of the color. The infusion of tea obtained from a tea leaf processed under normal conditions must be transparent and bright, and its characteristics must not be lower than the declared category of tea. Determining the color of tea and the intensity of its infusion are not the main evaluative features, but each grade of tea by leaf type must have a color intensity corresponding to it, below which the tea loses its rating in grade and is transferred to a lower grade, despite a high rating for aroma and taste. The intensity of the infusion is not evaluated in points, but is characterized by such definitions as “very strong”, “strong”, “above average”, “average”, “below average”, “weak”, “weak”.
Consumers place especially high demands on the color of black tea infusion, rightly believing that the more intensely colored the infusion, the higher the quality of the tea. Teas that have a brighter (intense) infusion and red color are defined as superior to duller brown teas or teas that have a greenish color. Dark (grayish-black) or cloudy color of the infusion indicates a defect in black tea. When the tea has a more brownish infusion, the leaf is over-fermented. A dark (grayish) infusion indicates that the fermentation process has been running for an excessively long time. When this phenomenon is accompanied by a sour smell and taste, the tea is not subject to evaluation. An overly light tea infusion with a greenish tint indicates insufficient fermentation and that the raw material has been processed too late.
It should be noted that high quality black tea, rich in tannins, has the ability to precipitate extractive substances - “tea cream”, which are obtained by cooling the tea infusion. "Cream" is a mixture of catechins and caffeine found in hot tea solution. When cooled, they stand out from the solution and are in suspension. With longer cooling, they settle to the bottom. The bright color of "cream" indicates a good quality tea, dull color is considered a negative phenomenon. Usually "cream" forms stronger teas. Assam tea has a "cream" color that looks like milk has been added to it. regular teas have a dull, heavy cream. It is characteristic that in light and fragrant infusions "cream" is not formed, but this does not at all reduce the value of tea.
When comparing the intensity of the infusion, it is also taken into account which type of tea belongs to - leaf or small. Fine tea has a more intense infusion than leaf tea.
3. The aroma of tea. In the organoleptic analysis, tea-testers attach great importance to the aroma index. This approach is based on the fact that the taste properties of tea, with the exception of rare cases, completely coincide with the aroma indicators. In the terminology of the foreign tea industry in English, the concepts of flowor and taste have long been distinguished; taste means exclusively a taste sensation, while flowor expresses a mixed sensation of aroma and taste, which reflects a direct relationship between them.
The specific aroma of tea is determined by the content of essential oils in it. Currently, up to twenty different components have been found in the composition of tea essential oils, including aliphatic and aromatic carbohydrates, aldehydes, acids, alcohols, phenols, ketones and other compounds. They are found in small quantities in green tea leaves and are formed during the production of tea, mainly as a result of oxidative processes. Already in the withered leaf, there is a slight increase in the amount of essential oils compared to the fresh leaf, however, during fermentation, the content of essential oils increases intensively, reaching a maximum at the end of the process. As a result of oxidative processes, essential oils undergo profound changes, a complex complex of volatile substances is formed, in connection with which the aroma of tea changes: the components of essential oils that give the tea the smell of a green leaf disappear, instead components are formed that give the tea a specific aroma and are characterized by the smell of roses, citrus fruits. , honey, etc. Their harmony determines the aroma of tea.
Since the fermentation process is typical for the production of mainly black and red tea, it is they who differ from other types in their special aroma.
To evaluate the aroma of tea, the teatester drains the infusion from the teapot and, after allowing the tea leaves to cool slightly, removes the lid from the teapot and determines the nature and strength of the aroma. Good quality teas have the following aroma characteristics: “pleasant”, “strong”, “delicate”, “rosy”, “honey”, “floral”, “lemon”, “bread”, “almond”. loose leaf teas. Defects in the bouquet of tea, its aroma and taste are considered to be “smoky”, “roasted”, “sour”, as well as the smell of greenery or grass, especially with hints of dampness and mustiness. The smell of dampness and mustiness occurs mainly under the action of microorganisms (bacteria) when storing tea in high humidity conditions. The reason for the musty smell may also be damage to the tea leaf before processing.
4. The taste of tea. Of all the indicators that determine the quality of tea, the most important role is played by taste, the properties of which are subject to special requirements. Therefore, the teatester pays special attention to the definition of this dignity of tea.
According to experts, deliciousness is a complex sensation perceived during testing as a result of exposure to smell-taste-touch impulses. When determining the taste of tea, tasters determine the degree of astringency and bouquet - a combination of two quality indicators - aroma and taste. There is a close relationship between aroma and taste, which is confirmed by the fact that in tasting both of these indicators, with minor exceptions, are generally evaluated in the same way in all varieties of tea. At the same time, the aroma and taste are directly dependent on other quality indicators of tea (appearance, color of the boiled leaf, color of the tea infusion). The more delicate, well-rolled leaves tea contains, the stronger (stronger) its infusion, the more the color of the boiled leaf approaches the standard of this type of tea (for example, reddish-light-copper color in black tea), the better the aroma and taste of tea .
Tea testers determine the taste of tea without swallowing, only rinsing their mouth with it, paying the main attention to its astringent properties and fullness. Depending on the astringent action of the infusion on the mucous membrane of the mouth and gums, the astringency of the tea is judged. Tea-testers distinguish strongly astringent teas from less astringent teas, they condemn the taste as bitter, “flat”, “empty”. A bitter taste and lack of astringency indicates the low quality of tea due to its excessive fermentation. In good teas, along with astringency, you should feel the extractiveness, or the "body" of the infusion, which in the tea-tester's assessment is defined by the word "full", that is, quite intense, strong and pleasantly tart. As a rule, broken teas are characterized by greater astringency and fullness of taste than leaf ones.
5. The color of the boiled leaf. The appearance of the boiled leaf (tea-boiling) is a fairly objective indicator of the quality of fermentation. It is directly dependent on the intensity of the infusion, aroma and taste of tea.
The boiling of tea is determined after the infusion is drained, and the boiled leaf is tipped over onto the lid of the teapot and squeezed out. In the best black tea, it has the color of a new copper coin, other shades of the boiled leaf (brown, green, dull, dark, etc.) indicate violations of the fermentation technology and characterize teas more Low quality. So, for example, a brownish color indicates that the leaf is overfermented, which is especially detrimental to the aroma of tea, and a dark (blackish) color, which usually results from overfermentation, is considered a defect. A boiled leaf of underfermented tea is always characterized by a greenish color. If the boiled leaf contains tea leaves of light brown and greenish color, this is due to the processing of heterogeneous raw materials, since, under the same technological regime, raw materials of different ambiguity react differently to technological processes during withering, twisting and fermentation. If most of the boiled leaf is well fermented, has a light brown color, but still contains a small amount of dark-colored tea leaves, this must be attributed to incorrect blending.
Blend. Compilation of trade grades of tea
Finished products of tea factories of primary processing - trade mark - are raw materials for tea-packing factories, which belong to tea recycling enterprises.
The main purpose of tea-packing factories is to prepare mixtures of commercial grades of tea from factory brands in strict accordance with approved recipes.
Commercial grades of tea, or trade blends, are prepared by blending several brand names that are identical in appearance and grade. Blending is due to the need to obtain a trade mixture with certain quality indicators (taste, aroma, infusion intensity, etc.), since individual brands usually do not have a set of these indicators. Tea is mixed (blended) by all large companies and they do it, first of all, in order to keep the main quality indicators of their tea unchanged, regardless of the results of the collection and processing of the leaf by raw material suppliers. For each brand of tea, there are several recipes depending on the incoming brands of tea. For example, there are special recipes for small and large types of tea, recipes for developing branded teas from the same or different places of growth. Special formulations of commercial tea varieties also provide for the use of imported tea.
The basic principle of compiling trade blends from teas different varieties and categories is not only to mechanically mix some components with others, but to skillfully combine all the quality indicators of different varieties of tea, taking into account the characteristics of individual regions, in order to obtain a mixture in terms of quality - aroma, taste and infusion - corresponding to a certain commercial grade. The finished product (trade mix) must have all the properties inherent in good tea. This delicate work is carried out by the teatester of a tea-packing or tea-pressing factory.
The advantages of tea largely depend on how correctly the quality indicators of individual tea components intended for inclusion in the trade mixture are selected by the teatester of the factory. In order to comprehensively take into account all the features of the quality of tea when compiling mixtures, the teatester of the factory checks the quality of each brand separately, evaluating its quality indicators by tasting - the appearance (cleaning) of the tea leaf, aroma, taste and intensity of the infusion. Tasters, in accordance with organoleptic indicators, select from a wide variety of raw materials those brands of tea that can create the most complete bouquet of the trade mixture.
Determining the quality of tea in retail
Tea in Russia is sold by more than 60 domestic and foreign firms. In the range of each seller - from tens to hundreds of items. In addition to the trademarks that everyone hears about, there is a whole sea of tea types with intriguing and completely new names, which appear more and more every year. In order not to be mistaken in the quality of the goods, to distinguish good tea from bad, real - from fake, and most importantly - to find "your" taste of a wonderful drink, you need to at least master the simple technique of choosing it.
According to experts, the taste and aroma of tea largely depends on the characteristics of the raw materials, the technology of its processing, the conditions of transportation and storage. Truthful information about where, when and how exactly all of the above processes took place must accompany each package of quality tea that enters the distribution network. Manufacturers encode this information in a special way using different letters and symbols that can be seen on the packaging.
According to the state standard, the label contains information not only about the variety, type, weight and shelf life of tea, but also the name, address and logo ( trademark) company responsible for the production of tea. Often, the packaging also indicates the date and time of the collection of the leaf, the number of the plantation. Trademark permission is issued by the National Tea Committee, so the National Tea Committee marks are considered to be a guarantee of a high quality product. So, tea produced in the state of Sri Lanka has a badge with a lion, and on the product of an Indian manufacturer, you can see the logo with a girl.
An important indicator of quality is the shelf life. If you cannot find it on the pack or it turns out that it has already expired, you should not buy such a product in any case - expired tea is not just tasteless, but, as is commonly believed in China, is harmful to health.
Tea is classified according to region of origin and leaf size. The name of the country where the native plantation is located must be indicated on the tea package. this tea, and the countries involved in the process of bringing it to the end consumer. For example, the words "Packet in Sri-Lanka" can be read on a pack of tea grown and packaged in Sri Lanka. It is generally believed that if the tea is packed in the same place where it was grown, this is a guarantee of quality. In fact, this is not always the case. Industry professionals argue that various violations in the packaging of tea are often found both at local tea recycling factories and at its direct producers. Therefore, the question of which tea is better - packed by the country of origin or locally packaged - does not have a definite answer. However, there is a traditional way to determine the quality of black tea: to do this, you need to boil water, brew leaves or a bag in it, and then dip a slice of lemon into the infusion. Genuine tea brightens significantly from this, and fake tea loses very little in color.
In the international black tea labeling system, there are separate designations for the tea leaf, depending on how it is rolled. tea produced traditional way, on the pack is marked with the word orthodox, and this is a sign of a high quality product. The letters "C.T.S" clearly indicate granulated tea.
On packs of loose tea, you can also find the English words pure or blended. Pure refers to a quality, single varietal tea. Blended indicates that the tea is blended, that is, it is a trade mixture from different plantations.
International classification designations of size and quality - tea leaves are present on the pack as a combination of several letters - both for whole-leaf (large-leaf) and for smaller ones (crushed). These designations were discussed above, so here we only note that on packages with elite tea they write in detail which leaf is included in the composition - type, first or second.
A lot can be said about the merits of the sheet, not only after deciphering the symbols on the package, but also by its very appearance. High-quality tea is sold packed in cardboard boxes, jars made of food tin, wooden boxes, glass or ceramic containers, it feels quite good in foil packaging. In fake packs, tea is wrapped in polyethylene, or even does not have an additional shell at all. Therefore, on the cardboard boxes of some manufacturers (for example, Ahmad, Lipton, Dilmah and others) there are small windows through which you can see how the tea is packaged.
Another indicator of quality may be the price of tea. However, it is a capricious value, depending not only on quality, but also on many other factors. On the one hand, the price of high-quality tea starts from 20-25 rubles per 100-gram pack, on the other hand, expensive does not necessarily mean the best. So, tea packaged in Ceylon, due to customs duties, costs 20-50% more than the same in all respects, but packed at a local factory. Although, of course, high-quality teas are expensive on the world market and can be a significant figure for individual brands (for example, such super-elite teas as Te Guan-yin varieties cost ten thousand dollars per kilogram).
Tea storage
The quality of tea during its storage usually deteriorates. When storing tea in the finished product, a number of transformations occur, which lead to a decrease in the content of esters and carbonyl compounds, tannin and extractives. In this case, tea loses aroma, taste and freshness, and therefore this phenomenon is often called tea aging. It should be borne in mind that if the storage conditions are not observed, even the most exquisite tea variety may turn out to be worse in terms of basic quality indicators than a low variety of good preservation.
English and Dutch technologists believe that the preservation of the quality of tea depends on the moisture content of the tea during packaging, the perfection of the packaging and the degree of its sealing, as well as the degree of sterility of the product.
As you can see, one of the main factors on which the change in the quality of tea depends is its humidity. After drying, during which the formation of a characteristic aroma and taste is finally completed, the tea has a moisture content of no more than 3-5%, but due to its hygroscopicity, if improperly packaged and stored, it can gradually absorb moisture, which significantly degrades its quality. So, with an increase in tea humidity by 4%, its quality decreases by 25-45%, depending on the shelf life.
Greens long leaf teas, differing from black long leaf teas in chemical composition, are characterized by lower hygroscopicity, since the technology for the production of green long leaf tea is fundamentally different from the technology for the production of black long leaf tea. The hygroscopicity of tea depends mainly on the content of tannins, proteins, pectins and other colloids in the tea. At present, it can be considered established that when storing tea, even under hermetic conditions, it is completely impossible to eliminate the aging process of tea, since oxidation inevitably occurs in it due to the oxygen and water contained in the tea itself and in the container. In this respect, the aging of tea can be considered as a continuation of the chemical processes that occur during fermentation, with the only difference being that during fermentation these reactions are vigorous, while in the finished product they proceed very slowly but continuously. Therefore, green tea has the best storage properties, since teas that are less fermented and with a high content of unoxidized tannin absorb moisture less than more fermented and low tannin.
The temperature of the external environment has a great influence on the preservation of the quality of tea. Hermetically packed tea at a low temperature (5-6 °C) is better preserved than at a high temperature (+35 °C), since at the same relative humidity of the ambient air, the intensity of moisture absorption by tea is the higher, the higher the air temperature, and vice versa. The size of the tea leaves also has some effect on the rate of moisture absorption. As a rule, small teas absorb moisture faster than large ones.
The decisive factor in preserving all the properties of tea is the container where the tea is stored, the degree of its sealing and quality characteristics the material from which it is made. The container must provide sufficient tightness to prevent the penetration of moisture and foreign odors. First of all, the aroma of tea suffers, as the amount of aromatic substances (volatile aldehydes and essential oils) quickly decreases, while the content of biologically active substances - amino acids, vitamins, catechins - decreases, which significantly devalues its healing properties.
The best containers for storing tea are jars made of food tin, glass or ceramic containers. It is advisable to place the contents of cardboard or wooden boxes in them after purchase - whether it is a scattering of fragrant leaves or bags. Cannot be used to store tea plastic bags or plastic products. In them, the tea "suffocates" and becomes moldy. You should also avoid storing tea near products or objects that have a characteristically strong odor, as well as in dusty rooms with high humidity and a large temperature difference.
Chapter 6 from Wu Wei Xin. Encyclopedia of healing tea»
