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19UDC 615.012.014. 664.68:664292: 663
Research
Annotation. This article provides an analysis of the cur >nt state of technology and technology for the production of pectin.The demand for pectin is moe higher than the volume of its production. The use of pectin is justified, it is extremely ne■ essary in conditions of environmental degradation and environmental pollution.
The quality of the final finished product - pectin, depends not only on physical and chemical processes, but also to large extent on the quality and method of preparation of pectin-containing raw materials.
It also an important side in the production of pectin is occupied by the processes of the preparation of pectin-containing raw materials, hydrolysis-extraction and precipitation of pectin substances, on the correct implementation of which the yield and physicochemical indicators of the target product depends on.
In this regard, the preparation of pectin-containing raw materials, research and development of technological modes and processes for the preparation of cotton fiber, as a new type of raw material, are relevant and have great scientific and practical importance.
As a result of the study, technological regimes, processes and methods for preparing a cotton fiber for the release of pectin substances have been established and developed:
-the most acceptable parameters for drying cotton fiber;
-the influence of long-term storage within 24 months of dry cotton fiber in the fiber composition and physicochemical parameters of pectin;
- the optimal size of the laminae of cotton fibers and in the process of hydrolysis-extraction;
- the proposed scheme for cleaning the cotton fiber from polyphenols;
- the process of swelling of dry cotton fiber.
Based on the research results, a technological line for the production of pectin from a cotton fiber has been developed. The pilot industrial production of powdered pectin has been mastered at the established experimental production "Pakhta" in the Chinaz district of the Tashkent region.
Keywords: pectin, pectin substances, organoleptic characteristics of pectin, complexing properties, gelatinous properties, pectin-containing raw materials, cotton fiber, pectin technology, storage of raw materials, temperature regime of drying, grinding of raw materials, hydrolysis extraction, washing of raw materials from polyphenols, swelling regime of dried crushed cotton fibers, food grade cotton pectin.
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Аннотация. В данной статье приведен анализ современного состояния техники и технологии производства пектина. Потребности в пектине намного превышают объёмы его производства.Обосновано применение пектина крайне необходимо в условиях ухудшения экологической обстановки и загрязнения окружающей среды.
Качество конечного готового продукта - пектина, зависит не только от физических и химических процессов, но и в большой степени от качества и способа подготовки пектиносодержащего сырья.
Важное место в производстве пектина занимают процессы подготовки пектиносодержащего сырья, гидролиза-экстрагирования и осаждения пектиновых веществ, от правильного проведения которых во многом зависят выход и физико-химические показатели целевого продукта.
В связи с этим подготовка пектиносодержащего сырья, исследование и разработка технологических режимов и процессов подготовки хлопковой створки, как новый вид сырья являются актуальными и имеют большое научное и практическое значение.
В результате исследования установлены и разработаны технологические режимы, процессы и способы подготовки хлопковой створки для выделения пектиновых веществ:
-наиболее приемлемые параметры сушки хлопковой створки;
-влияние длительное хранение в течении 24 месяцев сухой хлопковой створки в состав створки и физико-химических показателях пектина;
-оптимальный размер пластинок хлопковых створог и в процессе гидролиза-экстрагирования;
- предложенная схема очистка хлопковой створки от члифенолов;
-процесса набухания сухой хлопковой створки.
На основании результатов исследований разработана технологическая линия производства пектина из хлопковой створки. Опытно-промышленный выпуск порошкообразного пектина освоен на созданном экспериментальном производстве "Пахта" Чиназского района Ташкентской области.
Ключевые слова: пектин, пектиновы вещества,органолептические показатели пектина, комплексообразующие свойства, студнеобразующие свойства, пектиносодержащее сырья, хлопковая створка, технология пектина, хранение сырья, температурный режим сушки, измельчения сырья, гидролиз-экстрагирования, промывка сырья от полифенолов, режима набухания сушенной измельченной хлопковой створки, пищевой хлопковый пектин.
Аннотация. Ушбу маколада пектин ишлаб чикаришнинг замонавий техника ва технологиясининг холати тахлил килинган. Пектинга булган талаб ишлаб чикарилаётган микдорига нисбатан бир неча бор юкоридир. Пектиннинг атроф мухитнинг ифлосланиши ва экологикхолатнингёмонлашаётган биржараёнда ахамияти юцорилиги амалда исботланган.
Пектиннинг тайёр махсулоти сифатига нафакат физик ёки кимёвий жараёнларнинг таьсири, балки куп холларда пектин сакловчи хомашёнинг сифати хамда уни тайёрлаш холати хам таьсир этади.
Юкори сифатли пектин олишда, узида пектин сакловчи хомашёларни тайёрлаш жараёнлари жуда ахамиятли булиб, гидролиз-экстракция ва пектин моддаларининг чукма хосил килиши, бу модданинг микдори ва физик-кимёвийхусусиятларини белгилаб беради.
Шундайэкан, пахта толасинингпектин олишдахомашё сифатида фойдаланишда илмий изланишлар ва технология хамда жараёнларни ишлаб чикиш илмий ва амалий ахамият касб этади.
Илмий тадкикотлар натижасида пектинни ажратиб олишда пахта толасини тайёрлаш технологияси,усуллари ва жараёнлари ишлаб чикилди:
-пахта толасини куритишнинг макбул холати;
-пахта толасига узок муддатли, 24 ой давомида сакланганда толанинг ва ундан олинадиган пектиннинг физик-кимёвий хусусиятлари;
- гидролиз-экстракция жараёнида кусакларнингмакбулулчамлари;
- пахта толасидан полифеноларни тозалаш тизими таклиф этилди;
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- пахта толасининг увитиш жараенлариурганилган.
Тадцицотлар натижаларига асосланган холда пахта толасидан пектин олишнинг технологик тизими ишлаб чицилган. Кукунсимон пектинни ишлаб чицариш Тошкент вилоятининг Чиноз туманида жойлашган "Пахта"амалий ишлаб чицариш базасида ташкил этилган.
Таянч сузлар: пектин, узида пектин сацловчи моддалар, пектиннингорганолептик хусусиятлари, комплекс хосил цилиш хусусияти, геллашиш хусусияти, пектин сацловчи хомаше, пахта толаси, пектин олиш технологияси, хомашени сацлаш, цуритишнинг температура режими, хомашени майдалаш, гидролиз-экстракция, хомаше полифенол-ларини ювиш, пахта толасинингувитилган, майдаланган, истеъмолбоп пахта пектини.
INTRODUCTION
Pectin substances as a group of acidic polysaccharides, a component of plant raw materials, were discovered in 1825, in the 19th century and the first half of the 20th century, studies were carried out to study the chemical structure of pectin substances, to determine their quantitative content in various fruits, berries and root crops, the effect on the structural components of plant cells [1].
One of the most effective natural compounds for detoxification of the body from the harmful effects of radio nuclides, heavy metals and other toxic substances is pectin in and its forms, medicinal preparations and food products which are on it.
Pectin is extremely necessary for use in a balanced diet of certain categories of industrial workers, as well as for the population o. r gion^ of environmental degradation and environmental pollution, radioactive radiation.
The main reason that does not allow to increase the volume of production of pastilles of marmalade products is the insufficient provision of industries with gelatinous substances, including pectin.
Taking into account the special physicochemical and consumer properties of pectin substances, the search for new types of raw materials for the production of pectin, research, improvement and development of new technologies for its production is an urgent task due to the significant excess of its demand from the volume of production.
Depending on that, it remains relevant to find new ways to expand the raw material base of pectin production, to develop new technologies for obtaining pectin substances from various types of raw materials, in particular, from the fibers of cotton bolls.
The study of the complex influence of the main technological parameters on the processes of raw material preparation, hydrolysis-extraction and coagulation of pectin substances from an unconventional type of raw material - cotton fiber remains relevant and has great practical importance.
Cotton is thermophilic tropical plant with one and a half meters high. It tolerates drought well, but the soil must be moistened to obtain rich yields. Cultivated cotton is a herbaceous plant with a height of 70 cm to 2 m.
Mainly, Mexican cotton, which has medium fiber length, is grown in Uzbekistan. The longer and thicker the fiber, the higher is the fiber grade. The best ii^er is found in Uzbek and Egyptian cotton. It :s produced 16 thousand meters of fabric is obtained, from one ton of thick fiber of cotton, aid from 1 ton of medium-fiber of cotton only 8.5 thousand meters.
Cotton picking begins when the box bursts and white, fluffy fiber appears from it. The fiber is collected with seeds and fluff. All this mass is called raw cotton.
After opening the bolls by 80%, the cotton is processed to accelerate ripening, cotton picking begins after opening the bolls by 95%.
ЪШШШст
Cotton (Texas)
Then the seeds are separated from the cotton fiber and after that the oil is squeezed out. It is used for food, industrial oils, soap and other products are made from it.
The analysis and experimental studies have been carried out on a new non-traditional source of raw materials for the production of food pectin - cotton fiber - have been comprehensively carried out. Annually, in the cotton-growing republics of Central Asia, about 2 million tons of cotton fiber are
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formed, but practical application is not used properly.
The main producers of pectin from various r aw ■materials in the world market are Denmark, Germany, Great Britain, Switzerland, China, Australia and others.
MATERIALS AND METHODS
It should be noted that the structural features of pectin depend not only on the source of raw materials, but also on the degree of maturity of the plant raw materials. Pectin substances are found in various quantities in all parts of plants (leaves, seems, roots, fruits and seeds). They are differently localized in different parts of the plant cell [2, 3] and perform different functions.
The total content of pectin substances, the amount of protopectin and soluble pectin differ from depending on the species, age, conditions of growth and development of plants. This leads to differences in the technological parameters of the extraction and the physicochemical properties of pectin substances.
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Formula of pectin
According to date [4], the largest amount of pectin substances is contained in root crops, and they are the most widespread raw material available for industrial processing. The amount of pectin is different in various plants and the main difference depends on the consistence of monosaccharides.
Despite this, in different plants, the main quality indicators of pectin are the same, pectin is characterized with a high degree of esterification in apple fruits and leaves. In sugar the esterification of pectin is very low and it is observed that a high content of free carboxyl groups are kept [3].
The author believes that learning deeply the basic chemical, physicochemical and consum-
Строение пектина
er properties of pectin and pectin substances is
a logical basis for the study of nontraditional pectin-containing unconventional raw materials for the development of optimal and modern technology. It is obvious, that these indicators are important for the rational use of pectin in the food industry and other sectors of the economy.
The optimal prophylactic dose of pectin is no more than 2-4 g per day [3,12] for those in contact with heavy metals, in conditions of radioactive contamination - not less than 15-16 g [13]. Moreover, the pectin of the beet belongs to high complexing ability.
Jelly-forming ability is the most important property of pectin, which characterizes its consumer qualities for the confectionery and canning industries. To obtain a jelly of sufficient strength, v is necessary: 60% - sugar content, 0.5-1% pectin concentration, optimal pH (2.6-3.1).
In order to develop a universal pectin technology, which provides for the processing of various raw materials on one process - apparatus scheme, and to determine other industrial raw materials for the production of pectin substances, a classification of pectin-containing raw materials by the content of pectin substances has been drawn up and the features of the preparation of raw materials for hydrolysis-extraction and the technology of separation of pectin substances have been studied.
There are various methods of quantitative and qualitative determination of pectin substances based on their various physical and chemical properties. These methods are based on the formation of coagulum with organic solvents (alcohol, acetone) and inorganic mineral salts, flocculation with alkaline earth bases.
The most common classical method for the detection of different samples of pectin calcium pectate was widely used. This method allows you to determine separately soluble pectin and protopectin or the amount of pectin substances [30,31].
In some samples, a nephelometric and conductometric method for the quantitative determination of pectin substances developed by the authors G.B. Aimukhamedova and N.P.
Shelukhina was used in parallel[32].
To characterize pectin samples, it is necessary to determine their properties, ballast substances, ash content, content of pure pectin, free carboxyl groups, methoxylated carboxyl groups, acetyl groups, pH of a 1% solution of pectin, gelatinous ability, viscosity, molecular weight.
Physicochemical parameters of pectin samples were determined by the method OST-18-62-72 "Dry beet pectin"[33].
High viscosity is a characteristic feature of high qva1ity pectin solutions. The higher the viscosity s, the higher the molecular mass of the pectin will be, and, consequently, its jelly-forming ability. Oswald viscometers were used to measure t e viscosity, and the molecular weight was determined by the viscometric method[24].
Tn addition, in the process of performing the work, the following methods of determination and research were applied:
- mass fraction of gossypol GOST 13979.1183 [34];
- mass fraction of aflatoxins by chromatographic method [35];
-mass fraction of oxalates by titrometric method [36];
- mass fraction of phenolic compounds by photocolorimetric method [37].
Various varieties of cotton (Bukhoro-6, Namangan-77, "Boyavut", "Yulduz") from different regions of Uzbekistan (Tashkent, Bukhara, Namangan, Syrdarya regions) with different soil composition were used to study the quantitative composition of the content of pectin substances.
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Samples of the valve of the Tashkent-1 cultivar from the Tashkent region were laid for storage, observation was carried out for two years.
RESULTS AND DISCUSSION
The study of existing technologies for the extraction of pectin substances from various types of raw materials allows us to conclude that the organization of highly profitable industrial production of pectin production requires the necessary improvement of technological schemes and their hardware design based on deep scientific research, kinetics and the mechanism of processes.
Study of cotton fiber as a pectin-containing raw material for the production of food pectin:
Research has been carried out to study and research the cotton fiber as a pectin-containing raw material. Annually in the cotton-growing republics of Central Asia, more than 2.0 million tons of cotton shells produced do not find proper practical application, from which about 150 thousand tons of valuable food pectin could be produced.
Of the parts of cotton, the largest amount of pectin (up to 15%) accumulates in the valves [37], its content in leaves is 8.46%, in flowers - 8.2%, in stems with a crust from 2.75 to 4.2%. Its content is lowest in seed husks - 1.32%.
Cotton matures in a box under normal conditions in 65 days. The maturation of the cotton boll is accompanied by the maturation of the cotton. Studies have shown that the greatest accumulation of pectin substances in the cotton leaf is observed on the 45 th day of boll forma;jn. Depending on the year of sowing, on the 45th day, pectin substances in cotton accumulate in the i ange of 12.3 - 16.7.
The metrological conditions of the year also have a significant effect on the accumulation of pectin in the valve [38].
Agricultural clusters bring cotton fiber from farms, to cotton processing industry. After weighing the incoming batch, a thorough examination is carried out, an average sample of raw materials is taken from different layers of the embankment, at least 3 kg of the total mass. Important quality indicators of raw materials are moisture, mass fraction of impurities and microbial contamination.
Analysis and research of the quality of rtw materials by the author of the article in production conditions showed that raw materials supplied for processing, as a rule, contain 60-65% of pure leaves, 3035% of organic and mineral impurities, 2-5% of raw cotton.
Organic impurities consist of small parts of the stem, cotton peel, deformed or naturally dried leaves, tops and other parts of cotton.
The composition of mineral impurities includes, mainly, soil, stones, metal and other foreign objects. Raw materials which were ginneries contain no more than 35% of the fiber. It consists of mainly, small stems and other parts of cotton (60-62%), as well as insignificant (1-2%) amount of fluff with seeds.
The more the fiber is clogged with organic and mineral impurities, the lower the standard weight of the raw material and its procurement cost. It should be borne in mind that when cleaning doors with increased contamination, additional energy and chemicals are required.
The conditional weight of raw materials is determined by the following formula:
G . . (100 - C)
G d = -------........-- ,(1)
cond 100 J
where, Gcond - conditional mass of raw materials, kg;
Gphysic - physical mass of raw materials, kg;
C - clogged fibers, %.
Freed from raw cotton, organic and mineral litter, the shells of the cotton bolls are sent for storage. If the moisture content of the fiberes is more than 10%, then it is recommended to process them without storage or to dry them before storage. The residual moisture content of raw materials before storage should be no more than 8%.
The best way to store raw materials is to keep the crushed leaf in an atmosphere of sulfur dioxide, which excludes the development of microorganisms that cause spoilage of the material. To do this, the cleaned fiber is crushed, immersed in hermetically sealed reinforced concrete tanks, where, after full load-
ing, sulfur dioxide is fed (100-125mg / l of the tank volume). The crushed fiber is unloaded by pneumatic conveying devices.
In accordance with the requirements of normative and technical documents on standardization "Cotton boll fiber", the cotton fiber must meet the requirements specified in tables 1 and 2.[39].
Organoleptic characteristics of dry cotton fiber table 1
Organoleptic indicators Characteristics of raw materials
Appearance Loose, mold-free, dry
Color Greenish yellow to brown
Smell Specific without musty, moldy and other foreign odors
Physicochemical indicators of dry cotton fiber table 2
physical and chemical indicators Norm
Mass fraction of moisture,%, no more ^ I 8.0
Infection with microorganisms not allowed
Mass fraction of impurities: stems, leaves, tops, raw cotton, sand, etc.,%, no more 5,0
Maturity not allowed from unripe boxes
Note:The content of pectin substance, precipitated by alcohol must be at least 5.0%.
The quality of the final finished product - pectin depends not only on physical and chemical processes, but also to a greater extent on the quality and method of preparation of pectin-containing raw materials.
When producing pectin, special requirements are imposed on the preliminary preparation of raw materials, depending on its state (dried or wet) and the specified physicochemical properties of the pectin contained in it.[40,41,42].
According to the theory of mass transfer in a solid-liquid system, in order to accelerate the process of extracting the target product, it is necessary to achieve the maximum surface of the extracted particles and to provide unhindered access of the hydrolyzing agent to the inner parts of the plant cell. Therefore, regardless of the physical condition, it is necessary to ensure maximum crushing of the cotton fiber.
Dry pectin, isolated from plant materials, which has undergone thorough cleaning from extraneous mineral and organic impurities, is a white powder However, the presence in pectin-containing raw materials of such organic impurities as polyphenols, proteins and other ballast substances, change the color of pectin from light white to brown. Such pectin, containing a relatively large amount of soluble ash impurities, has low quality indicators and, above all, a low jelly-like ability.
For the production of cotton pectin, the raw material must be dried to a residual moisture content of 8%, must not contain organic and mechanical impurities, must not have foreign odors and must not be subjected to microbiological deterioration.
Among the ballast components accompanying the pectin substances of plants, the main ones are neutral polysaccharides, lignin, tannins and others. According to the research of A.K. Karimdzhanov (1996, Academy of Sciences of the Republic of Uzbekistan), cotton fiber contains up to 8% of phenolic compounds of catechin nature.
The transfer of these substances can contaminate pectin and thereby adversely affect its physico-chemical characteristics. Therefore, in the technology for the production of pectin from a cotton fiber, it is necessary to provide for the release of the fiber from polyphenols.
We have carried out studies on the content of organochlorine pesticides in cotton valves in comparison with the maximum permissible level (MPL) in cotton seeds and products of their industrial processing. The residual amount of pesticides in the boll valves was determined by the gas-liquid chromatography method developed for the cotton stems[43].
The results of the analyzes showed that DDT and DDE were completely absent in the valves of cotton bolls, 0.024 mg / kg of alpha-HCH was detected, and gamma-HCH-0.0041 mg / kg, which, respectively, 8.3 and 50 times less than their MPL for cotton seeds - raw materials for the production of vegetable oil.
Based on these studies, the cotton boll valves are classified as raw materials for the production of food products.
Cotton, especially its seeds, contains a specific pigment, gossypol. Depending on the species characteristics of cotton plants, the area of growth, the complex of agrotechnical measures (in particular, the amount and composition of fertilizers applied to the soil), the amount of gossypol during the growing season varies widely[44, 45].
As a result of the analysis, it was found that the content of free gossypol in the valves of cLttn bolls is 0.09%, bound gossypol is 0.03%. Hence, it can be concluded that the concentration of free gos-sypol in the valve of the cotton boll is at the same level as in the kernel of cotton seeds.
There is sufficient amount of concentration of pectin in cotton bolls, however, toxic components such as (organochlorine pesticides and gossypol) does not exceed their content in cotton seeds, as a result, we can conclude that the cotton bolls are promising and valuable raw materials for the production of edible gelatinous pectin.
In-depth scientific research on the chemistry and technology of pectin, on the standardization of technological processes and equipment, certification and assessment of the quality and safety of finished products - edible cotton pectin, has been and is being carried out, as well as, the range of confectionery products and soft drinks using cotton pectin is expanding.
The main stages of the technological process for the production of cotton pectin are the preparation of raw materials for the hydrolysis-extraction process, the extraction of pectin substances from plant materials (hydrolysis-extraction), coagulation and purification of pectin.
On the basis of numerous literature analyzes, the results of our own research and experimental experiments in laboratory and scientific-industrial conditions, a fundamentally new technology for obtaining food powdery pectin from an unconventional type of raw material - cotton fiber has been drv -'oped and tested.
Development of the temperature regime for drying raw materials: Among all types of pectin-containing raw materials, the cotton fiber which is by nature, in such a way that it most fully meets the technological requirements of pectin production. In the process of ripening, under the influence of sunlight and a stream of warm air, the cotton fiber is dried and practically after the collection of raw cotton, its moisture content is 7-8%.
Dried cotton fiber, unlike dried and squeezed apple and dried beet pulp, is ready for processing without the use of a heating agent. This is one of the distinctive features of the cotton fiber as a pectin-containing raw material for its industrial processing.
It is subjected to drying of the fiber with a moisture content of more than 10%. In this case, drying regimes for the cotton fiber should be developed, which should ensure the safety of the molecules of pectin substances and the physicochemical parameters of pectin in the cotton fiber.
From the results of the author's research [50] it can be seen that the temperature regime of drying has an effect mainly on the content of pectin substances in the cotton fiber, the ability to gelatinize and its color. With an increase in the temperature
and duration of drying (above 100 C for 2-2.5 h), the gel-forming ability of pectin decreases, as a result of the oxidation of phenolic compounds of the plant cell under the influence of atmospheric oxygen, the color of the valve changes from slightly brown to dark brown.
On the basis of numerous experiments of the author, it has been established that the optimal conditions for drying a cotton fiber, ensuring its high quality indicators, are drying at a temperature of 70 C for 1-1.5 hours with intense convection with hot air.
Changes in pectin substances during storage of cotton fiber: Studies have shown that when storing a cotton fiber with low humidity (7-8%), microbiological deterioration of raw materials does not occur, conditions are created for processing high-grade material and obtaining a high-quality drug [51].
In this regard, it became necessary to study the change in the state of pectin substances during storage of the leaf.
Samples of the valve of the Tashkent-1 cultivar from the Tashkent region were laid for storage, observation has been carried out for two years. During the storage period, the parameters of the ambient air fluctuated within the following limits: relative humidity - 70-82%; temperature from -18 to +45 C.
Table 3
Dynamics of changes in the content of pectin substances and the strength of the jelly
Storing cotton fiber for months The output of pectin substances per air-dry mass,% The strength of a standard jelly on the Sosnovsky device, mm Hg
2 month storage 7,95 668,0
6 month storage 8,0 684,0
10 month storage 8,10 653,0
14 month storage 8,12 684,0
18 month storage 7,78 638,0
24 month storage 7,76 653,0
The indicators presented in the table show that after the first 14 months of storage, no noticeable changes in the yield and quality of pectin substances are observed. The subsequent period of storage takes place a slight decrease in the content of pectin substances. All other indicators characterizing the quality of pectin remained at the same levelLj1].
Thus, the author's research has established that storage (24 months) of a dry cotton fiber under conditions of temperature fluctuations t = -18 + 45 C and relative humidity of the ambient air U = 70 - 82% does not cause any special changes in the composition and physicochemical parameters of pectin. ...
Establishing the optimum crushing degree of the cotton fiber:The peeled valve of the cotton boll is an ellipse-shaped petal l = 36-40 mm long, b = 15-20 mm wide and s = 1-3 mm thick. If the process of hydrolysis-extraction of the pectin substance is carried out with intact, undisturbed petals, then the extractant will slowly penetrate into the inner layers of the cell, and this important technological process will take an unreasonably long time[52].
The depth and rate of extraction predetermines the degree of crushing of the fiber; as it increases, the total surface of the particles increases, the porosity of the layer decreases, and the degree of interlocking of particles in the extraction process increases.
According to the basic law of molecular diffusion, the density of the diffusion flux is directly proportional to the concentration gradient dc / dn on the surface allocated in space:
j = D ( dc/dn ), (2) j = r dM/dF dx(3)
where, r - density, kg/m3;
M - mass of diffused substance, kg;
F - mass transfer surface, m2;
t - time, c;
D - molecular diffusion coefficient, m2/s.
Hence, the dependence of the mass of the diffused substance (M) on the diffusion surface has the form:
j d F d t
dM = .............., (4)
r
However, excessive crushing of the valve to a powdery state is technologically impractical, since this complicates the processes of flushing the valves from polyphenols and a large loss of raw materials during its washing, pressing the extracted mass and filtering the extract.
When it is grinded excessively, a solid mass is formed - slurry, in this situation it will be difficult to enter easily the extracting and, moreover a large amount of energy is spent while mixing mass [53, 54].
On the basis of research and numerous experiments, the author has established that the optimal size of the laminae of the cotton fiber in the process of isolating pectin substances, i.e. hydroly-
sis - extraction is 3.0 - 5.0 mm.
Development of modes for the technological process of washing raw materials from polyphenols:When pectin is extracted from plant tissue, proteins, minerals, sugars, enzymes, polyphenols, starch are transferred to the extract, thereby increasing the content of ballast substances and deteriorating the physicochemical parameters of pectin. The work of many researchers is devoted to the influence of substances accompanying pectin on its quality[55, 56].
Work [59] is devoted to the study of the qualitative and quantitative composition of apple polyphenols. Phenolic compounds of apples are represented by monomeric (catechin, leukoanthocya-nins, anthocyanins, flavonols) and polymeric forms (tannins). The content of polyphenols in Altai apple varieties ranges from 0.2 to 3.2%. According to data, [63] squeezing substances give a good effect while separating pectin.
The valve of cotton bolls contains a significant (up to 8%) amount of phenolic compounds, which is readily soluble in chloroform, diethylether, ethanol and other organic solvents [60].
To obtain high-quality cotton pectin, it is necessary to conduct the technological process in such a way that the product is maximally freed from
polyphenols. To achieve this goal, a number of studies were ca^ed out on the process of cleaning cotton fiber from polyphenols at all stages of the technological pr vctss.
The process of purification from polyphenols has been staved in two stages:
1) cleaning the fiber with a solution of mineral sj'ts;
2) purification of the obtained extract using synthetic ;on-exchange resins and adsorbents of organic origin: polyamide (PA), KU-2.
In the first stage of cleaning the va'vts from polyphenols, the effect of temperature, the duration of treatment, its hydronic modulus, as well as the concentration of mineral salts were investigated, and the optimal parameters of the process were identified. The determination of the amount of polyphenolic compounds before and after treatment was carried out with a photoelectric calorimeter according to the Folin-Ciocalteu method[61].
Experiments have shown [41, 62] that when using weak solutions of mineral salts, it is advisable to carry out the process of purification from polyphenols at high temperatures. The dependence of the depth of cleaning the cotton fiber on the concentration of sodium chloride and the processing temperature are graphically shown in Fig. 1.
As can be seen from Fig. 1, when a 5% solution of sodium chloride is used, 250 mg / l of the sum of polyphenols passes into the solution at a temperature of 70 C, and when using a 3% NaCl 225 mg / l.
Therefore, a 3% NaCl solution is the most suitable for cleaning cotton fibers from polyphenols, which ensures sufficient removal of polyphenols from the cotton fibers.
On the basis of experiments, it was found that to obtain pure raw materials, it is enough to hold the fiber in a 3% solution of sodium chloride for 30 minutes, at a hydromodule of 1: 8 and a temperature of 70 C.
Cotton fiber polyphenols are well removed by chloroform, alcohol, acetone. Chloroform extraction under laboratory conditions was able to isolate up to 2% of polyphenols, lignin, and other resinous substances.
However, the use of such toxic solvents requires the installation of complex extractors in production, which must ensure complete sealing of the system, for this reason, we refused to purify polyphenols with these solvents. The use of ethanol to purify polyphenols will greatly affect the cost-effectiveness of pectin production.
The content of polyphenols was determined in each batch of the produced dry pectin. In industrial pectin obtained by precipitation with aluminum chloride, 102-115 mg / l polyphenols were found, and in pectin obtained by alcohol precipitation 38-40 mg / l, at the same time, polyphenols in citrus pectin (made in England) were at the level of 18-20 mg /l.
Fig.1 Dependence of the content of polyphenols in the solution on the concentration of NaCl
and the temperature of the medium.
1 - 5% NaCl solution;
2 - 3% NaCl solution;
3 - 1% NaCl solution.
The maximum removal of polyphenols from the pectin composition during the purification process after precipitation of pectin substances also depends on the prr"tcsing time of the extract with acidified alcohol.
As a result of research, a method was proposed for cleaning cotton fiber from polyphenols with weak solutions of mineral salts at high temperatures. TVs allow s Lhe production of edible cotton pectin to significantly reduce the amount of related substances and improve the quality of the finished product.
Development of the swelling mode of dried -hopped -otton fiber:The technological scheme for obtaining food pectin from a cotton fiber is based on the processing of dried raw materials to a residual moisture content of 7-10%, the structure of which is a capillary-porous system. The rate at which these systems are filled with a hydrolyzing agent and the transfer of pectin substances from plant tissue depends on their diffusion capacity.
At various stages of the technological process, pectin-containing raw materials undergo significant changes in weight, structure and physicochemical composition[7, 63].
Hydrolysis of protopectin from the dried valve implies the swelling of plant tissue, while the effect of an acidic medium on the upper particle of the material is longer than on the internal one. This leads to
Dry crushed sash 100%
Hot water t = 80 ° C 800%
Fig 2. Material balance of the fiber washing process
partial depolymerization of pectin molecules and negatively affects the yield and gelatinous ability of the drug[64].
To identify physicochemical changes in the raw material, the kinetics of the preliminary swelling of the dried leaf was investigated. Fibers, weighing 100 g (humidity 8%), were placed in a thermostated beaker and filled with 800 ml of water at a temperature of 70 ° C.
After a certain time (30 min), the water was drained through the filter. The swollen pulp was weighed on a balance and the amount of water absorbed by the raw material was calculated. In water after swelling, a refractometer was used to determine the content of dry matter and pectin calcium by the pectate method.
It was found that water is intensively absorbed in the first 20 minutes, with an increase in temperature, the water absorption of the valve increases (Fig. 2.).
Water, filling the capillary system of the pulp, diffuses from the plant cell into the liquid of polyphenols, ballast substances and soluble pectins and thereby increases the concentration of dry substances in the liquid phase.
The modes of washing the raw material from polyphenols with a 3% NaCl solution for 30 minutes, at a hydromodule of 1: 8, at a temperature of 70 C. The balance of products is compiled during preliminary preparation of raw materials The calculation of products is made for 100 g of a dry leaf, consisting of: dry matter - 92 %, humidity - 8%, concentration of pectin substances - 10-15%.
The amount of absorbed water depends on the temper ature of the medium and the time the dry fiber stays in contact with the water. It has been experimentally established that 100 g of a dry leaf with a dry matter content of 92%, a moisture content of 8% a" an ambient temperature of 70 C can absorb 350 ml of water for 30 minutes.
Organic litter warehouse
J
Purification of raw cotton from raw cotton
Raw cotton
Padlock
Vermiculture cultivation
Purification of raw materials from organic impurities
Vermicompost with vermiculture
Cleaning raw materials from scraps of stems
Fertilizer for shipment
Vermiculture in cycle
Splitting up
Storage in a silo in front of the extraction workshop
Storing the cleaned sash
Fig. 3. Technological scheme for the preparation of a cotton fiber
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G + G2 = G1 + G3 ,(5) where, G - dry cotton fiber weight, 100 g;
G2- the amount of water supplied to swell the raw material, 800 g G1 - the amount of swollen pulp, 350 g;
G3 - amount of drained water, 550 g.
It has been experimentally established that the degree of extraction of pectin substances from the swollen pulp is 10-12% higher than that of the valve without preliminary swelling.
Taking into account the results of research and the properties of pectin-containing raw materials, a schematic diagram of the preparation of a cotton fiber for the hydrolysis-extraction process has been developed, which is shown in Fig. 3.
CONCLUSION
The increase in the production o. pectin depends on the search for these purposes of cheap, easily accessible technological plant raw materials, the development of fundamentally new technological schemes, taking into account the specificity of this raw material.
The quality of the final finished product - pectin, depends not only on physical and chemical processes, but also to a large extent on the quality and method of preparation of pectin-containing raw materials. An important place in the production of pectin is occupied by the processes of preparation of pectin-containing raw materials, hydrolysis-extraction and precipitation of pectin substances, on the correct implementation of which the yield and physicochemical indicators of the target product largely depend.
In this regard, the preparation of pectin-containing raw materials, research and development of technological modes and processes
for the preparation of cotton fibers, as a new type of raw material, are relevant and have great scientific and practical importance.
As a result of the study, technological regimes, processes and methods for preparing a cotton fiber foT the release of pectin substances have been established and developed:
-the most acceptable parameters for drying a Cotton f)ber ensuring its high quality indicators, are 70 ° C for 1-1.5 hours;
- long-term storage of a dry cotton fiber for 2 4 months under normal seasonal fluctuations at a temperature of -18°C + 45°C and a relative humidity of 70-82% does not cause any special changes in the composition of the fiber and physicochemical parameters of pectin;
- the optimal size of the laminae of cotton fibers and in the process of hydrolysis-extraction is 3.0-5.0 mm;
- the proposed scheme for cleaning the cotton fiber from polyphenols with a 3% solution of sodium chloride at a temperature of 70C for 30 minutes, a hydromodule of 1: 8 in the production of edible cotton pectin significantly reduces the amount of accompanying substances and improves the quality of the finished product;
- a dry cotton fiber with a dry matter content of 92%, a moisture content of 8% at an ambient temperature of 70C for 30 minutes absorbs 350 ml of water, while the degree of extraction of pectin substances from swollen pulp is 10-12% higher compared to raw materials without preliminary swelling.
The applied significance of the work is determined by the effective engineering and technological methods proposed in it and the principles of systematic construction of
technological schemes, which make it possible to organize a new production of pectin substances at the pilot-industrial level from an unconventional type of raw material of plant origin - cotton fiber
All this allows improving the quality and yield of the final target product, introducing a new technology for producing food pectin and expanding the range of food products based on it.
Based on the research results, a technological line for the production of pectin from a cotton fiber has been developed. The pilot industrial production of powdered pectin has been mastered at the established experimental production "Pakhta" in the Chinaz district of the Tashkent region. The production of 2.6 t of food pectin from cotton bolls was carried out and 72.0 t of marmalade was made on its basis for sale.
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