Organoleptic evaluation of tea. Determination of tea quality Methodology for determining the quality of tea by organoleptic indicators
INTERSTATE COUNCIL FOR STANDARDIZATION, METROLOGY AND CERTIFICATION
INTERSTATE COUNCIL FOR STANDARDIZATION, METROLOGY AND CERTIFICATION
INTERSTATE
STANDARD
Organoleptic analysis
Official edition
Standardinform
Foreword
The goals, basic principles and basic procedure for carrying out work on interstate standardization are established by GOST 1.0-92 “Interstate standardization system. Basic Provisions "and GOST 1.2-2009" Interstate Standardization System. Interstate standards, rules and recommendations for interstate standardization. Rules for development, acceptance, application, renewal and cancellation "
Information about the standard
1 DEVELOPED by the non-profit organization "Russian Association of Tea and Coffee Producers" ROSCHAYKOFE "(Association" ROSCHAYKOFE ")
2 INTRODUCED by the Federal Agency for Technical Regulation and Metrology (TC 451)
3 ACCEPTED by the Interstate Council for Standardization, Metrology and Certification (Protocol No. 62-P dated December 03, 2013)
4 By order of the Federal Agency for Technical Regulation and Metrology dated March 19, 2014 No. 189-st, the interstate standard GOST 32572-2013 was put into effect as a national standard of the Russian Federation from July 1, 2015.
Information about changes to this standard is published in the annual information index "National Standards", and a bunch of changes and amendments - in the monthly information index "National Standards". In case of revision (replacement) or cancellation of this standard, the corresponding notice will be published in the monthly information index "National Standards". Relevant information, notice and texts are also posted in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet
© Standartinform, 2014
In the Russian Federation, this standard cannot be reproduced in whole or in part. replicated and distributed as an official publication without permission from the Federal Agency for Technical Regulation and Metrology
|
(throughout the text of the standard) | ||
|
First page of the standard |
Date of introduction - 07-01-2014 |
Date of introduction - 07-01-2015 |
(ICS No. 2 2015)
INTERSTATE STANDARD
Sensory analysis Sensory tests
Date of introduction - 07-01-2014
1 area of use
This International Standard specifies a method for conducting sensory analysis.
This standard uses normative references to the following interstate standards:
4 The essence of the method
The method is based on a visual assessment of appearance and color tea leaf, on the olfactory and gustatory sensations of a specialist-taster (titester) caused by volatile substances contained in the analyzed tea infusion. and components of tea infusion. on a visual assessment of the color and color intensity of the boiled tea leaf.
5 Measuring instruments and utensils
5.1 Liquid glass thermometer with a temperature measurement range from 0 ° C to 100 V C with a tolerance limit of ± 1 ° C in accordance with GOST 28498.
6 Sampling
7 Requirements for specialist tasters
Organoleptic analysis is carried out by teesters with special knowledge and experience in assessing the organoleptic characteristics of tea.
8 Room requirements
The room for organoleptic anapysis should be well lit (without direct sunlight on the examination table), clean, isolated from extraneous noise. The walls of the room should be painted in light colors. The room temperature should be (22 ± 2) ° С.
9 Preparing for analysis
Infusion for determining organoleptic characteristics is prepared in accordance with GOST ISO 3103.
To determine the aroma and taste, the infusion is cooled to a temperature of (55 ± 5) * С.
10 Determination of organoleptic characteristics
10.1 General
10.1.1 Organoleptic analysis is carried out in the following sequence: determination of the appearance of the tea leaf, determination of the color of the infusion, determination of the aroma of the infusion, determination of the taste of the infusion, determination of the appearance of the boiled tea leaf.
10.2 Determining the appearance of a tea leaf
The method is based on a visual assessment of the appearance and color of the tea leaf. To determine the appearance of the tea, a portion of the pooled product sample is placed on a sheet of white paper. Particle shape. the uniformity and color of the tea is determined visually in diffused daylight or bright artificial light.
10.3 Determination of infusion color
When visually assessing the main color of the infusion, its saturation, shade and additional tones are noted.
10.4 Determination of infusion aroma
When evaluating the aroma of the infusion, its saturation and shades are noted.
10.5 Determination of the taste of infusion
For flavor assessment, use the contents of the bowl after flavor assessment. Taste sensations are assessed by the nature and fullness of taste, the severity of its shades, as well as the presence of flavor.
10.6 Determining the appearance of boiled tea leaves
For evaluation, the boiled tea leaf remaining after the preparation of the tea infusion. Placed on the inverted lid of the brewing vessel Determine the basic color and saturation of the boiled tea leaf.
10.7 If there is disagreement in the assessment of the organoleptic characteristics of tea, the dissenting party forms a tasting commission with the participation of a third party, the composition of which ensures equal representation of interested parties and independent experts.
The tasting committee conducts organoleptic analysis of tea samples. the results of which are binding on all interested parties.
11 Protocol for sensory analysis
The test report must contain:
Information required to identify the sample;
Information on the method of sampling;
Information about the circumstances that could affect the results of the analysis;
Analysis results.
UDC 663.95: 006.354 MKS 67.140.10
Key words: tea. organoleptic analysis, specialist taster (tester), appearance of tea leaves, color of infusion, aroma of infusion, taste of infusion, appearance of boiled tea leaves
Signed for printing 02.10 2014 Format 60x84V e.
Uel pec l 0.93 Circulation 62 copies Zak 4166 Prepared on the basis of the electronic version provided by the developer of the standard
FSUE "STANDARTINFORM". 123995 Moscow, Granatny lane, 4 www.gostinfo.ru [email protected] hi
Send your good work in the knowledge base is simple. Use the form below
Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.
Similar documents
Factors shaping the quality of tea. Basic production processes, chemical composition and requirements for the quality of black long tea. Analysis of the assortment of tea sold by the retail system. Quality examination, tea sampling and analysis.
term paper, added 11/21/2014
Chemical composition and nutritional value of dryers. Classification of dryers, their variety and range. Technological process for the production of donut products, features of the formation of their quality. Investigation of the quality of dryers by organoleptic indicators.
term paper, added 09/02/2013
Formation of the Russian tea market, an overview of the largest producers. Classification, properties and quality of tea. Influence of packaging on the preservation of consumer properties and quality of tea. Analysis of the assortment of tea sold at retail outlets.
term paper added 09/07/2015
Comparative assessment of the quality of children's fruit puree produced by manufacturers. Determination of quality indicators of fruit puree sold in the retail trade network. Substantiation of the commodity assessment of the investigated product.
term paper, added 05/18/2014
Assortment classification and characteristics sugar cookies... Chemical composition and nutritional value. Production technology and quality factors. Analysis of the quality and assortment of sugar cookies presented in the retail trade in Orel.
thesis, added 12/25/2015
Classification and modern assortment of chocolate. Formation of the quality of chocolate in the production process. Quality assessment by organoleptic indicators. Determination of the quality level. Development of a point scale for determining the quality level of chocolate.
term paper, added 03/31/2011
The nutritional value and the chemical composition of beer, the definition of the main factors that form its quality, the requirements. Methods for researching the quality of beer, criteria for its analysis and evaluation. Marketing research of the beer market in Krasnoyarsk.
thesis, added 05/14/2012
Nutritional value and chemical composition of semi-smoked sausages, factors that form and preserve their quality. The assortment of semi-smoked sausages, the requirements for their quality. Organoleptic quality assessment, packaging and labeling requirements.
term paper, added 04/06/2011
UDC 338.24
TASTING AS THE BASIC METHOD OF ORGANOLEPTIC EVALUATION OF TEA QUALITY
Kovalenko Tatyana Dmitrievna Penza State Technological Academy
Penza, Russia
Tasting as the main method of sensory evaluation complements objective methods of tea quality control. Organoleptic indicators of tea quality include: appearance, brightness and intensity of infusion, taste and aroma, color of the boiled leaf. The infusion, aroma, taste and color of the boiled leaf are determined after brewing the tea. Processing of the tasting results includes the calculation of the arithmetic mean of indicators, standard deviation and complex indicators of the quality of tea, taking into account the weighting factors. Based on the results of the organoleptic assessment of the quality of the samples, it is possible to draw conclusions about the quality of the 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 objective methods of quality control of tea. 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 the 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 infusion, taste and aroma, color of the boiled leaf. In appearance (cleaning) ready green tea represents smooth, uniformly twisted, tea leaves of various sizes (depending on the type of leaf). It possesses a delicate, delicate, characteristic green tea, pleasant taste with astringency. Its infusion is transparent, lemon-colored. The color of the boiled leaf is uniform, with an olive greenish tint.
To carry out the analysis, a sample weighing 100 g was taken from the average sample and poured into a thin layer on a sheet of white paper. The appearance of the tea was determined by inspection in ambient daylight or bright artificial light. At the same time, attention was paid to the color, evenness, uniformity and degree of curl of the tea leaves. The presence of petioles (red stems) or wood fibers in tea indicates that the tea is made from rough 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, a 3 g sample of tea was weighed on a technical balance and poured into a Titestor porcelain teapot with a capacity of 125 cm3, after which it was poured with boiling water, without refilling the kettle to the top by 4-6 mm, and quickly closed with a lid, after 1-1.5 minutes. ... proceeded to define the aroma. To determine the taste of the infusion, a little tea was sipped from a cup and, without swallowing, rolled 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 the tea. If the astringency is insufficient, the tea tastes empty. An infusion devoid of astringency is considered "watery" (low content of extractives in raw materials, weak curling of leaves, absorption of excess moisture in tea). In the course of the research, we used special tea utensils - gaiwan (porcelain, made in China, volume 125 ml. And a tea tool.
Chaou or gaiwan is a miniature tea brewing set. Includes cup, lid and saucer. Brewing in chaou is used when you need to taste tea, as well as for everyday tea drinking. A handy thing for quick tea brewing. This is an opportunity to look at the brewing tea leaves and smell them. Any tea can be brewed in a chaou. Brewing rules in gaiwan:
Heat the chaou with boiling water.
Pour tea leaves into chaow.
Rinse the tea leaves and drain the water immediately.
Pour 2/3 of the water down the side of the cup.
Wait 30 seconds, pour the tea.
Serve tea.
For various actions with tea during tea drinking, various tea devices have been used since ancient times. They are all called chaju. The metamorphoses of time influenced the variety of forms of the tea instrument. The composition of the toolbox has also changed in different times, but at the moment the most common set that we are describing has developed. A spoon is used to transfer tea from a tea caddy (Cha Yeguan) to Cha He. A needle (Cha Zan) is a wooden needle with a plastic or bone tip. It is commonly used to clear 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 the spatula are combined - on one side a needle, on the other a spatula. The funnel (Cha Xianglo) is used to prevent tea from spilling past the small teapot. Tongs (Jiazi) are designed to take hot cups for rinsing them, to get out the sleeping tea leaves.
The simplest methods of processing the results of tasting with a small number of experts (7 people) included calculating the arithmetic mean of indicators, standard deviation and complex indicators of the quality of tea, taking into account the weight coefficients. The quality categories of green tea are presented in Table 1.
Low 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
Highest 6.28-8
First, the assessments of experts, who were tasters, were averaged according to individual indicators, they were entered into summary sheets for each sample and the arithmetic mean value of estimates of single indicators (in points) was calculated using the formula
where I x is the sum of the assessors' assessments 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 was determined for each unit indicator according to the formula:
where I хг2 - the sum of the squares of the assessors' assessments, points;
х2 - the square of the average value of the indicator estimates, points.
The standard deviation S characterizes the consistency of expert opinions provided that the analyzed samples are homogeneous. Grades are unambiguous, S on a 10-point scale does not exceed ± 1 point. The results of testing the point scale are shown in Table 2.
table 2
Tasting sheet for organoleptic evaluation of the quality of green tea
No. Indicator Ko Numerical Characteristics of quality levels
n / and quality ef value of green tea
n phi levels,
t weight ohms
1 Aroma and taste 0.3 5 9-10 7-8 6 5 4 3 2 1 Sufficiently full bouquet, very delicate 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 tinge Transparent, light green, with a yellowish tinge Transparent, light green with a yellowish tinge Transparent, light yellow Transparent, light yellow with a pink tint Yellow with a reddish tint, not transparent enough Yellow with a red tint, not transparent enough Dark yellow with a reddish tint, dull
3 Color of 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 Not uniform , with a yellowish tinge Heterogeneous, yellow Heterogeneous, dark yellow
4 External 0.3 9 - 10 Fairly even, homogeneous, good
twisted view
(cleaning) 7 - 8 Smooth, uniform, well-rolled
6 Smooth, uniform, twisted (sheet); medium-leaf - smooth, twisted, with the presence of a 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, poorly twisted
1 Uneven, tea leaves are very poorly curled
The results of organoleptic assessment of the quality of samples of green Chinese
tea was drawn up in table 3.
Table 3
Organoleptic assessment of the quality of green tea samples
Sample No., name Quality indicators Weight coefficient Numerical value of levels, points (average score) Generalized quality indicator, points Quality category, grade
1 "Kudin Aroma and taste 0.35 1.1
middle lis Infusion 0.20 1.0 1.76 lowest
product "Boiled color 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
pearl "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 boiled 0.15 5.0
Appearance 0.30 3.3
4 Aroma and taste 0.35 1.7
"Eyelashes of beauties" Infusion The color of the boiled leaf 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
slightly scruff Infusion 0.20 5.3 3.52 medium
cured "Boiled color 0.15 4.0
Appearance 0.30 3.4
6 "Gunpowder Aroma and taste 0.35 4.0
silvery Infusion 0.20 5.0 4.14 medium
th "Boiled color 0.15 3.4
Appearance 0.30 4.1
7 Aroma and taste 0.35 2.4
"G anpaud 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
Spirals 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 Flask 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 The color of the boiled leaf Appearance (harvesting) 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 higher than good, which corresponds to the Russian analogue as the highest grade.
Samples No. 8; ten; 13 are of 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; are of 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 analogue as the second grade, III category.
It is known that obtaining a red leaf color in green tea production is undesirable. This may be due to incomplete inactivation of the enzyme complex, as a result of which the oxidation of tannins occurs, 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 aromatic and taste characteristics. ready-made tea, enhancing its chromaticity; as a result, the infusion of some tea samples had a pink tint (for example, sample no. 9).
Samples No. 1; 14 are of the lowest quality, which corresponds to the Russian analogue as the third grade. Such low quality of green tea samples can be explained by two reasons: qualitative 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. Technical conditions.
2.GOST 1936-85. Tea. Acceptance rules and methods of analysis.
3. Elizarova L.G. Expertise of the quality of tea. - M .: Moscow Higher School of Expertise, 2001 .-- 43 p.
4. Homeland T.G. Sensory analysis of food products. - M .: ACADEMA, 2004 .-- 208 p.
5. Khoperiya R.M. Tea production technology. - M .: Agropromizdat, 1988 .-- 160 p.
An analysis was carried out for compliance with the labeling of tea samples, label design, packaging condition, the requirements of GOST R 51074-2003 Food products. Information for consumers. General requirements, GOST 1938-90 Packaged black tea. Technical conditions, 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 was determined: appearance (harvesting), infusion color, taste and aroma, color of the boiled leaf in the following sequence. First, the appearance was visually studied, then a sample of tea was brewed and the color of the infusion, its aroma and taste were determined. The aroma of tea is better felt in boiled vapors. The color of the boiled leaf was studied after laying it on the teapot lid.
Good quality long tea should consist of uniform, well-twisted tea leaves, of the same size, without wood hairs, red petioles, yellow or green dust; Tea of the Bouquet variety should contain golden tips.
Preparation of infusion and assessment 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 covered with a lid. After 5 minutes, the infusion from the teapot was poured into a special porcelain cup, the teapot was shaken several times to completely drain the last purest drops of the infusion.
Tea analysis was carried out 1-1.5 min after pouring the infusion into a cup.
Analysis.
The color intensity, shade and transparency (purity) of the infusion were determined visually.
The aroma was determined in the vapors of the boiled tea. At the same time, extraneous odors and defects not characteristic of tea were revealed. Then, the taste of the tea was determined, noting the fullness, the severity and its astringency, as well as off-flavors not typical for tea. The color of the boiled leaf was determined after laying it on the teapot lid.
Infusion color.
The color of tea infusion is: weak, intense, cloudy. The infusion should be transparent, clean, copper-red shades.
A brown infusion or a cloudy infusion gives an over-fermented tea.
The dark color of the infusion indicates prolonged fermentation.
The greenish color of the infusion is typical for non-fermented tea.
The aroma of the infusion.
The specific aroma of black long tea is due to the content of essential oils, which are mainly formed as a result of oxidative processes during fermentation. The aroma of the tea should be delicate, subtle, floral, honeyed, etc.
Disadvantages of black long tea aroma: sour, burnt, (fried), green smell, musty, smoky, etc.
Sour smell - arises as a result of over-fermentation of raw materials, as well as in violation of the drying regimes or damage to the sheet during transportation.
Burnt odor (hotness) - in violation of the drying process.
The scent of greens is unfermented tea. Violation of the process of withering, twisting, fermentation.
Musty (damp smell) - occurs due to aging of tea under the influence of microorganisms when stored in conditions of high relative humidity or when the leaf is damaged by microorganisms before processing.
The taste of tea.
Determined to correct the endings "from the first person" throughout the text, determined, looked, poured, measured, etc. simultaneously with the aroma of the infusion. The leading role in the formation of taste belongs to tannins (tea tannin). Tea tannins 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.
A good quality tea should have a full flavor with astringency (the so-called "body" of tea). Tea that is devoid of flavor is considered "watery" or "empty".
The "empty" taste is the result of over-fermentation.
"Green" is a bitter taste without astringency, combined with a "green" aroma, arises from insufficient fermentation.
The color of the boiled sheet.
The color of the boiled leaf indicates compliance or violation of the technological regimes for processing tea leaves.
The color of the boiled leaf should be even, light brown.
Disadvantages.
A dark color is observed with excessive fermentation or excessive withering.
Variegated color - when processing non-fermented raw materials.
PAGE_BREAK--
1.2. Factors Determining Organoleptic Properties
The organoleptic properties of tea, and, consequently, its quality depend on many factors that develop gradually, starting from the moment the tea bush grows on the plantation and ending with the final stage of industrial processing - aromatization. These factors include:
· Conditions for the growth of a tea plant (soil properties, amount of precipitation, exposure to the sun, etc.);
· The conditions for collecting the tea leaf (the thoroughness of the collection, the type of collection - manual or machine, the type of leaves - the younger, the softer the collected flushes, the higher the grade of the finished tea);
· Time of collection of tea leaves (this indicator is individual for each geographic region);
· The nature of processing, technological scheme (more thorough processing without the slightest violation of technology gives higher grades;
· The nature of the additional processing (artificial aromatization and blending).
Organoleptic properties of tea largely depend on raw materials, technologies for its processing, as well as on storage and transportation.
1.2.1 Raw materials
It is important to know that not the entire leaf is harvested, but only the most tender, youngest, softest and most juicy leaves and a bud at the tip of the shoot. A bud, or tipsa, can be either just set or recently blossoming (fully blooming flowers are of no value for tea, since they do not convey their aroma to the tea leaves at all). Such a tip of the tea shoot (2-3 leaves and a bud) is called a flush. The best tea is made from it.
Tea harvesting can be done manually or with the help of machines. The manual method is considered the best (Indian hand-made teas are often labeled as classic), because hand-picked leaves are not damaged, in addition, collectors select only the best of them, immediately rejecting broken, dirty or diseased leaves. This method is also the most laborious: pickers usually have to work on steep mountain slopes, picking at least
Tea harvesting machines have been in use since the 30s of the 20th century. Modern tea harvesting machines are in many ways reminiscent of huge vacuum cleaners that "suck" the leaves from the tea bush. Typically, tea harvested by machines is considered to be of low quality and is used mainly for the preparation of small-leaf teas or for the pharmaceutical industry to obtain caffeine.
1.2.2. Production
The tea leaves are immediately transported from the plantation to the tea factories after being harvested. Typically, tea factories are built in the immediate vicinity of plantations, since a long journey degrades the quality of fresh leaves.
Tea production is a versatile process that includes standard tea leaf processing steps. The number of these stages and their specificity depend on what kind of tea they want to produce. In other words, what kind (or grade) of tea will be obtained from the harvested leaf depends entirely on the algorithm of its processing.
The most important stages of processing tea leaves are: withering, leaf rolling, fermentation, drying, sorting and packaging. finished products.
The main goal of the stage withering- dehydration of the tea leaf. In mechanized production, foliage is withered in special rotating drums (from 25 to
Task twisting- squeeze out as much tea juice as possible from tea leaves, destroying their structure. Twisting is carried out on special roller machines equipped with a vertically positioned cylinder without a bottom and a table round shape, the gap between which is
Fermentation- one of the main stages in the production of black tea. The term "fermentation" was first used in 1901 as the name of the oxidation process initiated by tea enzymes. Fermentation usually takes place without machine or human intervention. The fermentation process begins already during the rolling of the leaves and lasts from 2 to 3 hours. Yellow-green tea leaves acquire a reddish-brown color at this time. The room where fermentation takes place is maintained at a relatively low temperature and high relative humidity - 95-98%. For this, water is sprayed, the room is heated, and oxygen is provided.
Fermentation reduces the tannins, activates the caffeine in the tea and creates the conditions for the formation of new essential oils, which leads to the appearance of aromas characteristic of black tea - ranging from floral to fruity, nutty and spicy. The duration of the process should not exceed 4 hours, the fermentation is stopped exactly at the moment when the aroma of the tea reaches its optimal condition.
Drying the tea leaves at a high temperature is the only way to stop the fermentation process. If this is not done, the tea will simply grow moldy and rot. This process is delicate, because if you do not dry the tea, it will quickly deteriorate in packs, if you dry it out, it will simply char and acquire a disgusting burnt taste. The ideal drying result is dry tea raw materials, which contain no more than 2-5% water.
Drying It is produced by supplying hot air in special tea-drying machines at a temperature of 92-95 degrees C. Moreover, the temperature of the tea itself, a semi-finished product, reaches 70-75 degrees. The drying process takes 20-22 minutes. An important condition for the correct production of tea is also the rapid cooling of tea raw materials. The tea turns black during drying. Essential oils and the juice released during fermentation "sticks" to the surface of the tea leaves in order to give all the aroma only during brewing.
After the tea has dried and cooled, it sort according to the degree of crushing of the leaves (by sifting through sieves of different sizes) and classified. Tea is classified not only according to the area of cultivation, but also according to the size of the leaves and their serial number on the branch of the tea plant.
Finally, the last stage of production - packaging, or package, tea, which is held immediately after the tea is sorted. Traditionally, tea is packed in branded boxes lined with foil and paper, upholstered on the outside with galvanized sheet. In turn, such boxes are packed in additional boxes made of deciduous trees, and when transported by sea, they are still covered with jute cover. These precautions are explained by the fact that tea is very hygroscopic, it can absorb up to 13% moisture. Poorly packaged tea can grow moldy and lose its flavor.
Although tasting is not included in the tea production chain, the process is extremely important.
The first tasting usually takes place immediately after the end of production and before the tea is packaged. The color, aroma, taste of the drink and dry tea are evaluated by specialists called titters (from the English tea - "tea" and taste - "taste, experience"). In small sips from a bowl, the titester draws tea infusion into his mouth, enveloping his tongue and palate. After that, according to the rules, it is required to spit out the contents into a special vessel. One tester can perform 15-20 taste assessments, then a break is required. Tea testing is carried out only until noon: then the sensations dull. In addition to tasting with tea testers, the factory also carries out laboratory analysis of tea - biochemical, chemical, gas.
Before reaching the end consumer, the tea is tasted at least four more times - but this is done during the buying process. The tea is tasted once by the broker (or his expert), who will then distribute the tea samples to the importers. And then it is checked three more times by the importer's expert, who will then make an order to the broker. The tea is tried again after buying at an auction, just before shipment, to make sure that the purchased product matches the sample sent earlier. The final check occurs when the tea reaches its destination (to ensure that the quality of the tea has not been adversely affected by transportation). Only elite Chinese sorts of tea are not subjected to such a thorough and repeated check, since their quality is a priori considered to be impeccable.
2.
Practical part
2.1.
Tasting evaluation conditions
The exact establishment of the quality indicators of tea by means of organoleptic analysis largely depends on the conditions in which the tea is tasting.
The perception of the senses is influenced by many factors: the purity and relative humidity of the air, the temperature of the sample and the environment, the illumination of the room. So, the best air temperature in the room where the organoleptic analysis (tasting) is performed is considered to be 20-24 ° С, and the optimal temperature for the sample prepared for tasting is 80 ° С. The relative humidity of the air, which contributes to a better perception of odor in the organoleptic analysis of tea, is desirable to maintain at the level of 60-70%.
In the laboratory (tasting room), the possibility of penetration of foreign odors must be excluded. If there is an extraneous smell in the tasting room, it is impossible to accurately determine one of the main quality indicators - the aroma of tea.
An accurate determination of the appearance of tea, the intensity of the infusion and the color of the boiled leaf is possible only in a tasting room well-lit with natural light. Direct sunlight or artificial lighting does not allow to correctly determine all five quality indicators. When Sun rays fall directly on the tea infusion, it seems pale; the appearance of dry tea seems to be completely different than it actually is, since the penetration of rays forms a shadow from tea particles and distorts the idea of the appearance of the product. Under artificial lighting, it is impossible to accurately determine the color of the boiled sheet.
There should be absolute silence when tasting tea in the tasting room, because noise can distract the tester's attention and he can make a mistake. It has been noticed that under conditions of noise, the perception of aroma by the human olfactory organs is usually reduced.
Perceptual ability can also change depending on the state of health, mood, degree of fatigue and alertness, and personal hygiene. Therefore, the rules of tasting require that before the start of the tasting session, titters do not consume spicy, odorous and hot dishes, alcoholic beverages, do not use scented soap, perfume or cologne, avoid using any cosmetic products, and also do not have colds, be nervous, and do not get distracted.
In organoleptic analyzes, undoubtedly, the degree of fatigue of the tester during sampling of tea plays an important role. As a result of a nervous state, poor health or an assessment of an excessive number of tests, absent-mindedness may appear, impressionability may decrease, a state of physiological fatigue of the sensory organs (their adaptation) and mental inoperability may occur.
2.2. Tasting analysis scales and their characteristics
The organoleptic characteristics of products are non-measurable, the values of which cannot be expressed in physical dimensional scales. Characteristics of taste, odor, consistency and other sensory characteristics are given in qualitative descriptions. To translate quality into quantity, in expert assessment, dimensionless scales are used: usually in points, less often in fractions of a unit or percentage.
A point scale is an ordered collection of numbers and quality characteristics, which are brought in line with the evaluated objects according to the attribute being determined.
The point scale is used to assign objects of quantitative assessment, which is a measure of expressing the qualitative level of a feature. The scale is characterized by a range, or score, which is understood as the number of quality levels included in the scale, in other words, the number of evaluation points does not always coincide with the number of points, since the scores can be divided into fractions (1.1-1.5-1.7 points, etc.) or not all points can be used in the assessment (5, 10, 15, 20-50 points, etc.). For example, the scale with the highest rating of five points, graduated at 0.5 points, has the same range as the scale with the highest rating of 10 points and gradation at 1 point, and similarly the scale with a maximum rating of 100 points and gradation at 10 points. If these point scales do not use 0, then they all have the same range with 10 quality levels.
When developing point scales, the gradation of the scale is determined depending on the nature of the task, the quality of the experts, the required accuracy of the results and the possibility of a verbal description of the characteristics of the qualitative levels.
For an expert assessment of product quality, it is recommended to use scales with an odd number of quality levels, more often point scales with three, five, seven, nine quality grades are used.
An experienced taster is able to remember and distinguish only 6-10 quality levels of each indicator. A common disadvantage of scales that contain a large number of points or a large number of quality levels is the presence of “blind spots” with unsatisfactory marks, which, as a rule, are not used in the work of expert tasters.
The optimal scale satisfies the basic condition: each point of the scale must correspond to a different level of quality perceived by the average taster, and it is convenient to use a scale with the same number of points to assess individual quality indicators.
To ensure the distinguishability of the scale steps, it is necessary to give the tasters a description, which reflects the characteristic features of the gradations, which make it possible to clearly distinguish each level of the point scale from those bordering on it and expressing the degree of quality of the assessed indicator.
All over the world, a 10-point assessment of the quality of tea is accepted, where 0.25 points is a transitional step from one variety to another. Despite the same assessment system, the qualitative division of tea according to the Russian classification is fundamentally different from that used abroad. So, according to the international classification, long tea is divided into five groups according to its merit: high; above average; average; lower middle; short. There is a tea of exceptionally high dignity that does not belong to any of these groups. This tea is called Unique - unique (incomparable, exceptional).
According to GOST 1938-90 “Packaged black long tea. Specifications "according to quality indicators, tea is divided into five varieties:
· "Bouquet";
· Higher;
· First;
· Second;
· Third.
In accordance with the requirements of GOST, a tasting scale of 5-point organoleptic assessment of the quality of black long tea was compiled:
Leaf tea appearance (harvest)
Aroma and taste
Broiled sheet color
Overall quality assessment
Weight
Positive quality indicators
Smooth, uniform, well-rolled, with golden and silver tips
Bright, transparent, intense, "above average"
Subtle, delicate aroma, pleasant strongly tart taste
Uniform color with brownish red or light brown tint or bright copper color
excellent quality
Smooth, uniform, the tea leaves are well curled
Bright, transparent, "medium"
Delicate aroma, pleasant taste with astringency
Uniform with a light brown tint
Not flat enough, twisted
Not bright enough, transparent
Sufficiently delicate aroma, medium astringency taste
Insufficiently uniform, brown
Satisfactory
Negative quality indicators
Uneven, insufficiently curled, brown or red untwisted sheets
Transparent, "lower middle"
Insufficient aroma and astringency
Heterogeneous, dark brown color with a greenish tint
Bad (barely acceptable)
Uneven, poorly twisted tea leaves, stalks (red stems) or wood grain
Insufficiently transparent, cloudy, "weak"
Weak aroma, slightly tart taste, herbaceous smell
Heterogeneous, dull, tinged color
Very bad (technical defect)
When assigning weight factors, the greatest value was given to the indicator "taste and aroma", since it most fully reflects the ability of the product to fulfill its main purpose.
Five points corresponds to the description of the characteristics of the standard, which represents the highest (or world) level of product quality. Grades 4 and 3 points correspond to the first and second quality categories according to the requirements of the standard.
Points are awarded according to the following principle:
5 points - in relation to the assessed trait, tea has distinctly positive properties; the overall impression is completely harmonious. No defects or deficiencies were found.
4 points - tea has imperceptible defects or imperfections, it gives almost complete pleasure.
3 points - the positive characteristics of tea are worsened; the product has visible defects or imperfections; the assessment of pleasure is at an acceptable level.
2 points - it has flaws and defects, therefore, it does not meet the requirements of the standard. Pleasure is downgraded, but tea can be sold under certain conditions (for example, a proportional reduction in value).
1 point - tea has significant defects and disadvantages, therefore it is not suitable for consumption. However, the product may be intended for recycling. Such tea is not suitable for consumption. continuation
--PAGE_BREAK--
3. Tasting part
3.1. Setting up an experiment
The quality of the appearance of dry tea leaves, the intensity of the tea infusion, its aroma and taste are always checked, and the color of the tea leaves in the infusion is also assessed.
When conducting an organoleptic analysis, the quality and grade of tea is determined according to the following main features:
· 1. Appearance of tea;
· 2. The intensity of the infusion;
· 3. The aroma of the infusion;
· 4. Taste of infusion;
· 5. The color of the boiled sheet.
The infusion, aroma, taste and color of the boiled leaf are determined after brewing the tea. To do this, 3 g of tea is weighed, and poured into a porcelain teapot, 125 ml of freshly boiled water is poured. The teapot is quickly closed with a lid, and the infusion is kept for 5 minutes.
During the infusion of tea, the titesters examine the dry tea leaves in the tea pack. The appearance (harvesting) of dry tea is determined by examining it in diffused daylight or bright artificial lighting.
When determining the appearance of dry tea, attention is paid to the color, evenness, uniformity and curl of the tea leaves. Attention should also be paid to the content of golden hairs of wood, untwisted leaf blades and other inclusions in long tea. The presence of golden and silver tips indicates that the tea is made from delicate high-quality raw materials. When properly processed, the unopened buds of the tea plant acquire a light golden color during the drying process. The presence of petioles (red stems) or wood fibers in tea indicates that the tea is made from rough raw materials and is poorly sorted. The more petioles or wood fibers the tea contains, the lower its quality.
Brown and red untwisted leaves can be found in black long tea, which is explained by the delay in processing the tea leaf, which does not curl well and does not ferment. The more brown leaves in the tea, the poorer its quality.
At the end of the brewing period, the infusion is poured into a special white porcelain cup so that the boiled tea leaves do not get into the infusion. When pouring the infusion into a cup, make sure that the infusion is completely poured out of the teapot. The kettle is shaken several times so that the last thickest drops of infusion are completely drained into the cup.
In the infusion of tea, its characteristics and taste are determined, and in the tea left after pouring out of the teapot - the aroma and color of the boiled leaf.
When characterizing the infusion, attention is paid to its transparency, intensity and color. Bright color and always accompanying transparency are a reliable sign of high quality tea, which cannot be said about color.
A brown, dark, cloudy color is considered a fault and indicates a violation of the technological regime.
The determination of the taste and aroma of tea is not started immediately after pouring the infusion, but after 1-1.5 minutes. During this time, the brewed leaf in the teapot cools slightly, which contributes to a better assimilation of the aroma. When hot, it is impossible to detect the actual aroma of the tea. But one should not hesitate with testing more than 1.5 minutes. The more the tea cools in the teapot, the more difficult it is to capture its aroma. When cooled, the aroma of superior quality tea cannot be distinguished from inferior quality tea.
Before trying a tea infusion, you need to study the color of the infusion, its shades, transparency and aroma. The aroma is used to assess the tenderness, fullness and strength of the tea bouquet. To determine the aroma of tea, quickly open the lid of the teapot, bring it to the nose and, strongly drawing in the air, evaluate the smell.
Tea can have a full bouquet, delicate, light pleasant or a faint, harsh aroma depending on the variety. In Tiester's practice, a special terminology has been adopted to determine the aroma of high-quality tea: rosaceous, almond, chalky, citrus, a mixture of aromas of strawberries, geraniums, and black currants, etc.
Unwanted odors in the aroma of tea are the result of a violation of technology or improper storage: hotness, green smell, mustiness, smoky, moldy and other odors uncharacteristic for tea. To determine the taste, a little tea is sipped from a cup and, without swallowing, rolled in the mouth, evaluating the taste sensations. The taste of the tea can be tart, not tart enough or rough, depending on the commercial grade.
The astringency and fullness of the taste of the infusion is a sign of the high extractiveness of teas, their high P-vitamin activity. Tea that lacks strength or fullness is considered “watery,” empty, and may be caused by a weak curl or a lengthy fermentation process. Unfermented tea always has a bitter taste.
Evaluation of the color of the boiled leaf gives a reliable indication of the quality of the tea.
The boiled leaf is laid out on the lid of the teapot and its color is determined.
The color of the boiled leaf is in direct proportion to the intensity of the infusion, aroma and taste of the tea.
When determining the color of a boiled leaf, pay attention to its uniformity: the lower the grade of tea, the less uniform the color. It can be light brown to dark brown for black long tea.
The dark color of the boiled black long tea leaf is usually observed with excessive fermentation or excessive withering of the tea leaf; in case of insufficient fermentation, the color remains green. The high-quality tea has a boiled leaf of a bright copper color.
As a result of the tasting evaluation, the following defects may be found:
· Weediness (with stalks, coarse leaves, fibers and other impurities) occurs as a result of collecting coarse tea leaves from bushes, including during machine harvesting and insufficient cleaning during sorting;
· Mixed tea is obtained as a result of improper drying (high temperature and slow advance of the tea in the dryer);
· Sour taste and smell arise due to the disturbance of the process and duration of fermentation, drying;
Roasted tea is formed as a result of direct drying
(high temperature and slow advance of tea in the dryer);
· The gray color of the tips is the result of excessive friction during dry sorting of tea and prolonged curling of the leaf;
· "Watery", "empty taste" of the infusion may be due to excessive weak curling or too long fermentation of the tea leaf;
Lifeless infusion (tea with an insufficiently astringent taste) appears as a result of increased leaf moisture and
"Steaming" tea during drying;
· Green tea (the presence of the aroma of "green" and bitter taste) arises as a result of insufficient fermentation;
· Black color of tips is typical for tea of May or June collection and with excessive drying of the leaf;
The dark color of the boiled leaf appears due to excessive fermentation and excessive wilting;
· The variegated color of the welded sheet is formed during processing and sorting of heterogeneous material;
Musty, moldy and other extraneous odors occur due to violation of the sheet storage technology and high humidity
(more than 90%) of tea during storage. Such tea is not suitable for consumption.
3.1.1 Participants
Participants in the tasting evaluation are regular customers who prefer to drink black tea. They are not professional testers, their assessment will be based on their own experience and preference.
The purpose of the tasting assessment is to determine the quality of the studied tea samples, as well as to identify the best sample among them.
3.1.2. Objects
Millions of people around the world start their day with a fragrant cup of an energizing drink that tones and invigorates, giving a boost of energy for the whole day ahead.
In accordance with the preferences of consumers who, according to surveys, prefer black Indian or Ceylon tea, 2 samples of black long tea were purchased for the tasting evaluation:
1 sample - black long leaf Ceylon tea BOP 1 "AhmadTea";
Sample 2 - Ceylon black long leaf tea "Greenfield Golden Ceylon" Greenfield.
Both trade marks teas have been on the Russian market for a long time and have managed to gain consumer confidence. In addition, they hold leading positions in sales in Russia.
3.1.3. Organoleptic analysis methods
Depending on the task, various methods are used, which can be divided into three groups:
· Methods of acceptability and preference (preference, desirability, satisfaction);
· Methods of distinctiveness (comparison, discrimination, differentiation);
· Descriptive methods.
Acceptability and preference methods are used when it is necessary to know the opinion of consumers about the quality of products, therefore, a large number of consumers are usually attracted to tastings.
Distinguishing methods are used when it is required to find out whether there is a difference between the evaluated samples. Some of the methods in this group also allow you to quantify the difference. Distinguishing methods are also widely used to test the sensory abilities of tasters. Differential methods include pairwise comparison, triangular (triangular), duo-trio and some others.
Descriptive methods can be used to summarize the parameters that determine the properties of a product, consider the intensity of these properties, and in some cases, the order of manifestation of individual constituent properties of the product, i.e., construct property profiles (for example, profiles of taste, odor, product consistency). Descriptive techniques require the involvement of well-trained teams of professionals. In sensory analysis methodology, descriptive methods are the most important. Only when there is a detailed description of the products and the described properties are labeled according to the intensity of manifestation, it is possible to detect true differences, or drift, of the product, that is, a barely noticeable, gradual displacement of characteristics within a certain period of time.
Descriptive methods are widely used in profile analysis and product quality scoring systems.
Depending on the degree of preparedness and qualifications of the tasters, organoleptic methods can be divided into consumer methods, which are based on the desirability scale, and analytical methods, based on the intensity scales of a particular impulse.
Consumer evaluation is simple, accessible, and often has one goal: to determine whether a product is liked or disliked. The appraisal commission should consist of at least 20 people, preferably 30-40.
Consumer assessment methods. They aim to check the reaction of consumers in connection with changes in recipes and technological regimes. Simultaneously with the new product, it is necessary to evaluate the existing product prepared in the traditional way. Since consumers are very different, the following conditions are recommended.
To involve a wide range of consumers in the assessment, preferably from the region where the product will be sold. In this case, one should be guided by the opinion of such a category of persons for which the product is intended.
In consumer evaluation, tasters can use the simplest one-off test, comparing the evaluated sample from memory, or use a more advanced control evaluation method based on comparing the characteristics of a food or flavoring product with those of a control sample.
The system of preference and acceptability, which is more often used in consumer assessment, using the scale of desirability, makes it possible to single out not only the best sample, but also the degree of its desirability, depending on some factor: changes in the recipe, storage conditions and periods, technological regime, etc. Percentage undesirability is calculated as the ratio of unwanted ratings for each sample to the total number of ratings.
The preference method is based on determining the degree of preference for one or more samples selected from a number of samples presented for evaluation using hedonic scales (from the Greek hedone - pleasure). The hedonic scale reflects the degree of acceptability and preference in the "like - dislike" interval.
Analytical methods of organoleptic analysis. They are based on a quantitative assessment of quality indicators and allow you to establish a correlation between individual characteristics. Analytical methods include paired comparison methods, triangular (triangular), duo-trio, rank, profile, dilution index method, scoring method, etc. The tasting commission should consist of 5-9 people with special knowledge, skills and proven sensitivity.
Distinguishing methods.
Analytical methods include groups of qualitative and quantitative discriminatory tests. The first group includes comparison methods: paired, triangular (triangular), two out of three (duo-trio), two out of five, A-not-A, as well as rank (ordinal). Qualitative difference methods answer the question of whether there is a difference between the evaluated samples in one of the quality indicators (taste, smell, consistency, appearance) or the general impression of quality, but do not answer the question of what is the difference between the samples.
Quantitative discrimination tests include the dilution index methods and the scoring method. These methods allow you to quantify the intensity of a particular property or the level of quality of the product as a whole.
Qualitative distinctive methods: paired comparison, triangular (triangular), duo-trio, two out of five - based on the comparison of two similar samples A and B with weak differences. Samples can be presented as a pair (paired method), as samples from three samples (two of which are identical) or as samples from five samples (one sample is repeated in a sample two times, the other three times). Samples must be coded. The probability of a correct answer when submitting a paired sample is 50%, in a triple sample - 33.3%. To ensure the reliability of the results, the samples are repeated several times, and the order of supplying the samples in the set is changed each time. The methods are used when it is necessary to verify whether there are differences between two product samples. These tests are also used in the selection of tasters.
Paired comparison test according to ISO 5495.
The taster is asked to evaluate 6-8 coded pairs of samples. In pairs, two samples that differ little from each other are completed. In all pairs, the same samples are offered, but in a random sequence, for example AB, BA, BA, AB, etc. The evaluator is asked to determine in each pair a sample with a higher degree of manifestation of the trait.
The method is used to test the sensory abilities of tasters. In a set of paired samples, no more than one error is allowed.
The pairwise comparison method is convenient to use to find out the influence on the quality of the product of any factor: changes in the recipe, mode technological process production or storage, use of a new type of packaging, etc. Tasters are offered sets of paired samples. The answer may be to recognize the samples as the same or different from each other. Only one property can be assessed at a time (for example, aroma or consistency, or other property). If different properties are to be compared, the test must be repeated as many times as the product properties are evaluated. The pairwise comparison method can also be used in cases where it is necessary to find out which of the two products is preferable.
Triangular (triangular) and duo-trio methods. They are used to determine weakly expressed differences. Triangular test to ISO 4120 and Duo-trio test to ISO 10399.
In the triangular method, three samples are compared, two of which are identical. Samples are coded and assembled in the form of blocks, for example, according to the following scheme: BAB, AAB, ABA, ABB, BAA, BBA, BAB. The evaluator is offered from three to seven triple blocks, in which identical ones must be determined. In seven triple tests, no more than two taster errors are allowed.
When using the duo-trio method, the taster evaluates first a standard sample and then two samples, one of which is identical to the standard. Two samples are completed in the form of six to seven paired samples, which are coded. The evaluator is asked to determine in each pair a sample identical to the standard one.
Triangular comparison (triple test) and duo-trio methods are more accurate than the pairwise comparison method. They can be used for analytical purposes to differentiate individual quality indicators, as well as in the selection of tasters.
At a large number samples, the reliability of organoleptic analysis in the methods of paired and triangular comparisons is achieved by processing tasting sheets using the theory of probability.
Method two out of five. Requires two samples A and three samples B (or vice versa) with slight differences. Samples are assembled in blocks of five, coded and offered to the taster, for example, according to the scheme ABBAB, BBAAB, ABABB, AABAB, ABABA, BABAA. The task is to differentiate the samples in each block, dividing them into two groups: with a less intense and more intense degree of severity of a certain trait.
This method is more efficient than triangular and pairwise comparison, but time consuming. In addition, taster fatigue increases with this method, so the two out of five method is rarely used.
Method of single stimuli (method "A-not-A") according to ISO 8588 "A" not "A". It consists in the fact that after preliminary acquaintance with the standard sample (A) and samples of products that differ from it (not A), the taster identifies them in a series of coded samples.
The multiple standards method consists in selecting from a given batch the sample that is significantly different from the reference materials representing the product in several forms.
Ranked method.
When using this method, the taster is asked to rank the randomly submitted coded samples in the order of increasing or decreasing the intensity of the evaluated sign. The method can be used to assess the quality of products, as well as to test the visual sensitivity of tasters.
In this method, also called ordinal, it is not necessary to orient the tasters to any standard or limit the scale, since the comparison is carried out directly between samples. The method is simple, fast, and allows a large number of samples to be analyzed simultaneously.
The rank method does not provide an indication of the magnitude of the differences between samples. The results from one test are not compared with the results of another test, since the taster does not compare the sample with any standard. This test is recommended when it is required to isolate samples of greatest interest from a number of products in order to subject them to more accurate analysis by other methods.
Quantitative discriminatory methods allow one to quantify the intensity of a particular property. This group includes the dilution index and scoring methods.
Dilution index method.
Designed to determine the intensity of odor, taste, color of the product by the value of the limiting dilution.
The method consists in the fact that the liquid product is subjected to a series of increasing dilutions until a concentration is obtained at which individual indicators are not organoleptically captured. The indicator (index) of taste, smell, color is expressed by the number of dilutions or the percentage of the original substance in the solution. For example, the aroma of cherries disappears if the juice is diluted with water in the ratio (1:30) ... (1:40). The table shows the dilution indices for syrups and tomato concentrate (according to Tilgner and Barilko-Pikelna data).
The method for calculating the dilution index includes the determination of two values: the detection threshold and the recognition threshold. The term "detection threshold" means the minimum value of a stimulus (stimulus) that causes a barely noticeable sensation, not qualitatively determined. The recognition threshold is the minimum value of a stimulus (stimulus) that allows one to identify the received sensation. The higher the dilution index value, the more pronounced the intensity of aroma, taste, color or goodness (in general) of the product.
The method allows you to observe the change in a particular stimulus (flavoring, aromatic, etc.) of the product depending on any factor (conditions of production, storage, etc.) and to express this change in the form of absolute numbers reflecting the dynamics of the process depending on the impact of this factor.
The scoring method, or points (the second term is more used in the domestic literature), allows one to quantitatively evaluate the qualitative characteristics of products and opens up great opportunities for studying the correlation between the organoleptic properties of products and objective parameters measured by instrumental methods.
Descriptive methods.
Based on a verbal description of the organoleptic properties of the products.
The description of organoleptic indicators is given in all standards and other documents that establish requirements for the quality of food raw materials, food and taste products, is widely used in the identification of food products - one of the most important procedures in commodity examination and certification.
Descriptive analytical methods include profile analysis and a scoring system. It is the responsibility of descriptive methods to use precise terminology that does not allow for confusion. In the profile and scoring methods, scales are widely used to quantify the qualitative characteristics of products.
Profile method.
It is based on the fact that separate gustatory, olfactory and other stimuli, when combined, give a qualitatively new sensation of deliciousness (flavor) of the product. Isolation of the most characteristic elements of taste and smell for a given product makes it possible to establish the profile of the goodness of the product, as well as to study the influence of various factors (feedstock, production modes, packaging, storage conditions, etc.). First, the odor profile is determined, then the taste and consistency. The tasting committee checks the profile of the reference sample several times. Chemically pure substances, which are key for a given product in terms of smell or taste, can also serve as standards. According to the standard, the terminology of sensory signs, the order of appearance and the intensity of individual stimuli are specified. Then, the intensity of sensations in the samples used is assessed according to a conventional scale. Various scales can be used to assess the intensity of the characteristic features.
The results obtained by the profile method and statistically processed can be represented graphically in the form of rectangular profiles, semicircle profiles or as full circle profiles.
This method can be used to characterize the profiles of individual quality indicators of products: appearance, smell, taste or consistency. The most convenient method for assessing the quality of products with complex characteristics of signs.
Point method.
Used for differentiated organoleptic analysis by highly qualified tasters. The method allows you to establish the levels of partial (for individual indicators) and general (for a set of indicators) quality. The results of the assessment are expressed in the form of points on a conventional scale with an increasing sequence of numbers, each of which corresponds to a certain level of a particular quality indicator. When using a scientifically grounded scoring system and observing other basic requirements, the scoring method allows you to obtain fairly objective, reliable, well reproducible results.
In the domestic practice of organoleptic analysis, various principles for constructing point scales are known. There are 3, 5, 7, 9, 10, 13, 20, 30, 50 and 100-point scales for sensory analysis of food products.
Modern requirements are most fully met by 5-point scales using weight factors (importance, significance) for individual quality indicators.
The weighting coefficients of the unit quality indicators of the evaluated products are established by an expert method using ranking, evaluation or other methods. Sometimes the weighting factors are obtained by calculation.
Scientifically grounded point scales of organoleptic assessment, developed taking into account the principles set forth, are simple, easy to use and make it possible to fairly reliably differentiate foodstuffs by quality levels. continuation
--PAGE_BREAK--
-
April 17, 2015Black Lord - who is he -
April 17, 2015Mlp fanfic Pony fanfic read without registration -
April 17, 2015Mlp fanfic fanfiction my little pony ficbook
