RU2010540C1 - Method for production of pectin - Google Patents

Abstract

FIELD: food industry. SUBSTANCE: method involves introducing cellulose phosphate additionally into a blended mixture of beet pulp and apple pomace taken in a mass relation of 1: 1-9 The amount of cellulose phosphate is 2-4% of the mass of mixture. Hydrolysis is carried out with a mixture of aqueous solutions of hydrochloric and acetic acids which is additionally treated with milk whey heated in advance and held at 90-95 C for 15-25 min. Acidity of said mixture is 290-300 T and mass relation of hydrochloric, acetic and lactic acid contained in whey is, respectively, 1: (0.220-0.660) : 0.374-0.943). EFFECT: higher efficiency. 4 tbl

Description

 The invention relates to the food industry, namely to the production of pectin from plant materials used in the manufacture of confectionery and medicine.

 A known method of producing pectin, providing for the swelling of apple pomace in a solution of acetic acid with a pH of 4.0 - 4.5, hydrolysis with hydrochloric acid, separation of the hydrolyzate, cooling [1].

 A significant drawback of this method is that a strong acid is used for hydrolysis - hydrochloric, which does not allow creating favorable conditions for the carboxyl groups of pectin, which negatively affects its gel-forming ability. In addition, the production of pectin from apple pomace is unprofitable due to the low content of pectin substances in raw materials (5 -15%) and the imperfection of the technological process. The pectin obtained by this method has a low yield and low quality indicators, which necessitates blending it with citrus pectin to obtain confectionery products that meet the requirements of the standard.

 The closest to the invention in technical essence and the achieved result is a method for producing pectin, comprising preparing a blend of beet pulp and apple pomace, swelling the mixture in an aqueous solution of acetic acid, washing with water, hydrolysis with a mixture containing aqueous solutions of hydrochloric and acetic acids, separation of the hydrolyzate , its cooling and neutralization, precipitation with ethanol of 96% concentration, its purification and drying [2].

 The disadvantage of this method is that in the hydrolysing mixture of acids, citric acid is used, which is scarce and expensive. For the production of 1 ton of pectin by this method, 74 kg of citric acid are required, the cost of which from the cost of pectin is 22.3%. In addition, the use of a triple mixture of acids: hydrochloric, acetic and citric for hydrolysis does not allow to increase the proportion of beet pulp in the blend mixture by more than 30%, without compromising the quality of the obtained pectin. Despite the fact that the introduction of 10-30% of beet pulp into the blend increases the yield of pectin, however, the cost of pectin remains relatively high.

 Thus, the known method does not allow the rational use of material resources for the production of pectin and improve its quality in color, purity and student-forming ability. Therefore, this invention is aimed at solving this problem.

In the proposed method for the production of pectin, including the preparation of a blend of beet pulp and apple pomace, swelling the mixture in an aqueous solution of acetic acid, washing with water, hydrolysis with a mixture containing aqueous solutions of hydrochloric and acetic acids, separating the hydrolyzate, cooling and neutralizing it, precipitating with ethyl alcohol 96% concentration, cleaning and drying, the difference is that the mass ratio of beet pulp and apple pomace is 1: (1-9), cellulose phosphate is added to the blend mixture in a quantity TBE 2 - 4% by weight, and hydrolyzing the mixture of aqueous solutions of hydrochloric and acetic acid is additionally introduced preheated and maintained at 90 - 95 ^{° C} for 15 - 25 min whey acidity of 290 - 300 ^o T, wherein the weight ratio of hydrochloric, acetic and lactic acids contained in whey is 1: (0.220-0.660): (0.374-0.943).

 To justify the optimal composition of the blend mixture consisting of apple squeezes and beet pulp, pectins were experimentally obtained at various ratios of pectin-containing raw materials and the gel-forming ability was studied.

 It was found that an increase in the gelling ability of pectin is observed when the ratio of beet pulp and apple pomace from 1: 1 to 1: 9.

 If for 1 hour of beet pulp there is less than 1 hour of apple squeezing, then the proportion of beet pulp, a source of low methoxylated pectin, increases sharply in the blend mixture, which sharply reduces the quality of the obtained pectin by its gelatin forming ability and purity.

 If for 1 hour of beet pulp there is more than 9 hours of apple squeezing, then pectin with a gelatin-forming ability close to apple pectin was obtained from such a blend, while the yield of pectin increased slightly, which had little effect on reducing its cost.

 It is known that the pectin substances of beet pulp and apple pomace located in the cell wall are firmly bound (via arabinans and galactans) to cellulose and proteins. When using a mixture of acids to produce pectin, selective hydrolysis occurs, i.e., bonds between pectin substances are broken, on the one hand cellulose and protein, and on the other hand, they, at the same time, slightly degrade the pectin micromolecules themselves. The protection mechanism of the pectin molecule is as follows. The basis of all pectin substances is polygalacturonic acid, consisting of residues of D-galacturonic acid and connected by α -1-4 glycosidic bonds. Moreover, polygalacturonic acid is not in a free state, and part of its carboxyl groups is esterified with methyl alcohol. At the same time, L-arabinose, D-galactose, and L-rhamnose participate in the construction of the main chain of pectin substances together with D-galacturonic acid. And, as a result, the properties of pectin substances are largely determined by galacturonic acid. Galacturonic acid is slightly acidic; its degree of dissociation is 5–6%.

 Pectin substances are labile macromolecular compounds, upon receipt of which in a state close to the native and maximum conservation of their molecular chain, specific conditions for the hydrolysis of the pectin content of the raw material are required. Such specific hydrolysis conditions are created by a mixture of acids consisting of hydrochloric, acetic and lactic. The introduction of carboxylic acids with a low degree of dissociation into the hydrolyzing agent promotes the formation of a large number of undissociated carboxyls in the medium, which suppress the dissociation of pectin substances.

 The use of lactic acid contained in whey allows more selective hydrolysis and creates sparing conditions for the methoxyl and carboxyl groups of pectin molecules. This is due to the fact that lactic acid is slightly acidic, the degree of dissociation is 3.7%, which is more than two times less than the degree of dissociation of citric acid (8.6%). Acetic acid is also slightly acidic, the degree of dissociation is 1.34%. Therefore, a mixture of carboxylic acids - acetic and lactic, in comparison with acetic and citric, will give a larger amount of undissociated carboxyls to the hydrolyzing medium, and with their increase, the efficiency of screening of the negative charges of the pectin molecule increases. The use of lactic acid in a mixture of acids for hydrolysis allows not only to improve the quality of the obtained pectin by the gel-forming ability, purity and color, but also to increase the proportion of beet pulp in the blend mixture. In addition, lactic acid is less deficient than citric acid. The ratio of hydrochloric, acetic and lactic acids in the hydrolysis mixture should be 1: (0.220 - 0.660): (0.374 - 0.943).

 If the ternary mixture contains acids for 1 h of hydrochloric acid, less than 0.220 h of acetic acid and more than 0.943 h of lactic acid, the quality of the obtained pectin decreases due to its gel-forming ability and purity.

 If the ternary mixture contains acids for 1 h of hydrochloric acid, more than 0.660 h of acetic acid and less than 0.374 h of lactic acid, the quality of pectin in terms of gelding ability also decreases, while the yield of pectin decreases, which affects its cost.

The use of whey as a source of lactic acid for the preparation of a hydrolyzing mixture allows the rational use of material resources through the disposal of secondary products of the dairy industry. Whey is one of the cheapest and most affordable types of acid-containing raw materials. High-acid whey is obtained by fermenting lactose with lactic acid bacteria (L. bulgaricus and L. acidophilus) at a temperature of 45. . . 50 ^C. High temperature of fermentation serum hinders the development of foreign microflora and for a short time (1 - 2 days) these microorganisms transferred to 90% of the lactose into lactic acid. The lactic acid contained in serum has no color, is more active in acidic properties and does not contain anhydrides. This provides not only a reduction in material costs for obtaining pectin, but also improves its quality in color, purity and student-forming ability. However, when using whey to prepare a hydrolyzing mixture, not only lactic acid is added to it, but also up to 0.8 - 1.0% protein, up to 0.4 - 0.8% minerals per 100 g of product. Serum proteins, being non-sugars, react with glucose and fructose to form dark-colored compounds, which reduce the quality of the resulting pectin. In addition, protein substances form insoluble complexes with mineral salts, especially calcium, which are deposited on the surface of heating apparatus, reducing the heat transfer rate and worsening the sanitary condition of the equipment. Serum proteins also form complexes with pectins, making it difficult for them to precipitate and dry. Therefore, whey is purified from minerals and nitrogenous compounds, and, above all, from whey proteins.

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Фосфат целлюлозы получают фосфорилированием целлюлозы производными кислот пятивалентного фосфор. Фосфат целлюлозы содержит порядка 5% фосфата, а его обменная емкость составляет около 2,6 - 3,2 моль/г.Serum proteins are highly hydrated and in their native state. They are divided into thermolabile fractions of proteins (β-lactoglobulin, α-lactoalbumin, serum albumin, immunoglobulin) and heat-resistant (proteose-peptones). Heat treatment of whey allows you to clean it from the heat-sensitive fraction of whey proteins. The heat-resistant fraction of whey proteins, non-protein nitrogen compounds (peptides, amino acids, urea, purine bases and others), as well as minerals are removed using cellulose phosphate (cation exchange resin in the H-form):

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Cellulose phosphate is obtained by phosphorylation of cellulose with pentavalent phosphorus acid derivatives. Cellulose phosphate contains about 5% phosphate, and its exchange capacity is about 2.6 - 3.2 mol / g.

 Cellulose phosphate is a fibrous cellulosic sorbent having a developed specific surface in the form of many channels and pores, which are preserved after chemical modification. By its chemical nature, cellulose phosphate is a multifunctional cation exchange resin containing strong and weakly acidic groups. As polymeric acid, cellulose phosphate ion-exchange binds simultaneously proteins and minerals of both whey and pectin-containing raw materials in the process of producing pectin hydrolyzate. During sorption of proteins and minerals, mainly strongly acidic groups of cellulose phosphate are involved in the reaction, which contribute to the production of pectin with a high content of free carboxyl groups. Phosphoric acid released as a result of the exchange suppresses the dissociation of the second, weakly acidic group of cellulose phosphate, which, together with lactic and acetic acids, screens the pectin methoxyl groups, which provides a greater number of esterified groups in pectin and, as a result, a high gel-forming ability.

Cellulose phosphate is added to the blend mixture, which allows sorption of protein and metal ions at all stages of pectin production. Wherein the step of hydrolysis - the extraction at 75 - 77 ^{° C} maximum sorption properties appear cellulose phosphate, as the temperature rise increases the sorption properties of the cellulose phosphate. This ensures the purification of pectin hydrolysis from proteins and minerals contained in whey, apple pomace and beet pulp.

The amount of cellulose phosphate introduced into the blend is determined experimentally by the quality of the obtained pectin. The quality of pectin was evaluated by its gelatinous ability and the content of Ca ²⁺ , Fe ²⁺ and Mg ^{2+ ions} . The experimental data are presented in table. 1.

As follows from the table. 1, the introduction of cellulose phosphate in an amount of 2 - 4% by weight of the blend mixture allows to increase the gel-forming ability of pectin to 82 - 85 kPa. It should be noted that the resulting pectin contains 78 - 80% less Ca ^{2+ ions} , 30 - 35% less Mg ^{2+ ions} and 25 - 30% less Fe ^{2+ ions} . The addition of cellulose phosphate in an amount less than 2% by weight of the blending mixture does not provide an improvement in the quality of pectin in terms of color, purity and gel-forming ability. The introduction of cellulose phosphate in an amount of 4% by weight of the blend mixture is also impractical, since the quality of the obtained pectin and the content of metal ions in it remains at the level achieved with the addition of 4%. Therefore, the optimal dosage of cellulose phosphate into the blend when using whey should be 2 - 4% of its mass.

 Heat treatment modes and the acidity of high-acid whey are established experimentally, changing its acidity and heating to various temperatures. The degree of purification of whey from proteins was evaluated by the amount of protein released, in% of its weight. The experimental data are presented in table. 2.

As can be seen from the table. 2, the largest amount of protein released (42.7 - 48.5% of the total protein mass) is observed when heating whey with an acidity of 290 - 300 ^о Т to a temperature of 90 - 95 ^о С. It is impractical to heat whey to a temperature below 90 ^о С, since the degree of its purification from whey proteins is deteriorating. It is also undesirable to heat whey above 95 ^о С, as it spontaneously boils up and copious foam release. With a whey acidity of 290-300 ^о T, an isoelectric point of whey proteins is reached at which thermocoagulation of the thermolabile fraction of proteins occurs. As an increase in the acidity of whey above 300 ^about T, and a decrease in its acidity less than 290 ^about T, the degree of purification of it from whey proteins is deteriorating. In 100 g of high-acid whey with an acidity of 290 - 300 ^about T contains 2.6 - 2.7 g of lactic acid.

 The process of coagulation of whey proteins occurs over time, which can be divided into two stages: on the first, the intramolecular bonds of the protein are broken (slow process), and on the second, the structure and shape of the protein particles are violated (fast process). The degree of purification of whey from whey proteins depends not only on the heating temperature, but also on the duration of the heat exposure. The duration of the heat treatment was determined experimentally, by the amount of protein released from whey. The experimental data are presented in table. 3.

As follows from the table. 3, the heat treatment duration whey at a temperature of 90 - 95 ° ^C should be at least 15 minutes, but no more than 25 minutes. When the duration of heat treatment of whey is less than 15 minutes, insufficient protein denaturation is observed and its degree of purification is insignificant, at the level (42.7 - 44.0%) of the initial amount of protein released. It is also inexpedient to increase the duration of heat treatment of whey for more than 25 minutes, as the whey darkens, which negatively affects the quality of the obtained pectin by color, purity and gel-forming ability.

 The method is as follows. Beet pulp and apple squeezes are mixed in a mass ratio of 1: (1-9), cellulose phosphate is added to the blend mixture in an amount of 2 - 4% of its mass and poured for swelling with a solution of acetic acid with a pH of 4.0 - 4.5 with a water module 1: 10. The resulting mixture was stirred and kept at room temperature for swelling for 1.0 - 1.5 hours, then it was filtered, the swollen raw material was washed twice with water and loaded into a hydrolyzer.

In parallel, heat treatment of whey is carried out to purify it from whey proteins. Whey acidic with 290 - 300 ^{of the} T are heated to 90 - 95 ^{° C} and held for 15 - 25 min for coagulation proteins. The coagulated proteins are separated from the serum and cooled. To prepare a hydrolysing mixture of acids with a pH of 0.6 - 0.8, purified milk whey, hydrochloric acid, and acetic acid are poured into the container (the ratio of hydrochloric, acetic, and lactic acids ranges from 1: (0.220 - 0.660): (0.374 - 0.943). hydrolyzing the resulting mixture was poured into the acid hydrolysis hydrolyser feed is performed for 1.0 - 1.5 hours at 75 - 77 ^{° C} and liquor ratio 1:. 10. After hydrolysis, the hydrolyzate was separated, it was cooled and neutralized with sodium carbonate to pH 2.2 - 2.4. Pectin is precipitated with ethanol of 96% concentration. alcohol per volume of hydrolyzate is equal to (2 - 3): 1. Pectin coagulum with a moisture content of 70 - 75% is loaded into a washer, in which it is purified with an aqueous solution of alcohol of 70% concentration at a ratio of 1: 8. After the first purification, pectin coagulate again loaded into the washer, where it is again cleaned with 90-95 vol.% alcohol in a ratio of 1: 8. After the second washing, the pectin is separated in a centrifuge and fed to a vacuum dryer for drying. The pectin was dried at a temperature not higher than 60 ^C. The dried pectin was ground in a hammer-mill to a powder with a particle size of not more than 0.4 mm.

 PRI me R 1. In a container load 50 kg of beet pulp and 50 kg of apple pomace (ratio 1: 1), add 2 kg of cellulose phosphate (2% by weight of the blend) and pour 1000 kg of acetic acid and pH 4 , 0 (hydraulic module 1: 10). The resulting mixture was stirred and kept at room temperature for 1.0 h. Then the mixture was filtered, the swollen feed was washed twice with water and loaded into a hydrolyzer.

In parallel, heat treatment of whey is carried out to purify it from whey proteins. Whey with an acidity of 290 ^about T is heated to 95 ^about C and incubated for 15 minutes to coagulate proteins. After heat treatment, whey is filtered to separate whey proteins and cooled. To prepare a hydrolyzing mixture of acids with a pH of 0.6, purified milk whey is poured into the container, hydrochloric acid and acetic acid are added (the ratio of hydrochloric, acetic and lactic acids is 1: 0.660: 0.374). The resulting hydrolysis mixture of acids is poured into the hydrolyzer.

The hydrolysis of the pectin raw material was carried out for 1.5 hours at 75 ^{° C} and liquor ratio of 1: 10. After hydrolysis, the hydrolyzate was separated, it was cooled and neutralized with sodium carbonate to pH 2.2. Pectin was precipitated with ethanol 96% concentration in a ratio to the volume of alcohol hydrolyzate volume ratio of 2: 1. After purification twice pectin coagulum was dried at ⁶⁰ ° C until a moisture content of 8%, then it is crushed. The yield of pectin is 83.5% of the content of protopectin in beet pulp and apple pomace, the purity is 82.1%, the gel-forming ability is 82 kPa.

 PRI me R 2. Into a container load 30 kg of beet pulp and 70 kg of apple pomace (ratio 1: 2.33), add 3 kg of cellulose phosphate (3% by weight of the blend) and pour 1000 kg of acetic acid solution with pH 4.2 (water module 1: 10). The resulting mixture was stirred and kept at room temperature for 1.25 hours. Then the mixture was filtered, the swollen feed was washed twice with water and loaded into a hydrolyzer.

In parallel, heat treatment of whey is carried out to purify it from whey proteins. Whey with an acidity of 295 ^about T is heated to 93 ^about C and incubated for 20 minutes to coagulate proteins. After heat treatment, whey is filtered to separate whey proteins and cooled. To prepare a hydrolyzing mixture of acids with a pH of 0.7, purified milk whey is poured into the container, hydrochloric acid and acetic acid are added (the ratio of hydrochloric, acetic and lactic acids is 1: 0.441: 0.658). The resulting hydrolysis mixture is poured into the hydrolyzer.

The hydrolysis of the pectin raw material is carried out for 1.25 hours at 76 ^{° C} and liquor ratio of 1: 10. After hydrolysis, the hydrolyzate was separated, it was cooled and neutralized with sodium carbonate to pH 2.3. Pectin is precipitated with ethanol of 96% concentration with a ratio of the volume of alcohol to the volume of the hydrolyzate equal to 2.5: 1. Then, the pectin coagulate is twice purified. The pectin was dried at 60 ° ^C to a moisture content of 8% and milled. The yield of pectin is 84%, purity 82.5%, gel-forming ability 85 kPa.

 PRI me R 3. In a container load 10 kg of beet pulp and 90 kg of apple pomace (ratio 1: 9), add 4 kg of cellulose phosphate (4% by weight of the blend) and pour 1000 kg of a solution of acetic acid with pH 4 5 (hydraulic module 1: 10). The resulting mixture was stirred and kept at room temperature for 1.5 hours. Then the mixture was filtered, the swollen pectin-containing raw materials were washed twice with water and loaded into a hydrolyzer.

In parallel, heat treatment of whey is carried out to purify it from whey proteins. Milk whey with an acidity of 300 ^about T is heated to 90 ^about C and kept for 25 minutes to coagulate proteins. After heat treatment, whey is filtered to separate whey proteins and cooled. To prepare a hydrolysis mixture of acids with a pH of 0.8, purified milk whey is poured into the container, hydrochloric acid and acetic acid are added (the ratio of hydrochloric, acetic and lactic acids is 1: 0.220: 0.943). The resulting hydrolysis mixture is poured into the hydrolyzer.

The hydrolysis of the pectin raw material was carried out for 1.0 hours at 77 ^{° C} and liquor ratio of 1: 10. After hydrolysis, the hydrolyzate was separated, it was cooled and neutralized with sodium carbonate to pH 2.4. Pectin is precipitated with ethanol of 96% concentration with a ratio of the volume of alcohol to the volume of the hydrolyzate equal to 3: 1. Then, the pectin coagulate is twice purified. The pectin was dried at 60 ° ^C to a moisture content of 8% and milled. The yield of pectin is 83.7%, the purity is 83%, the gel-forming ability is 84 kPa.

 In the table. 4 shows comparative quality characteristics of pectin obtained by the proposed and known methods. From the data table. 4 shows that a distinctive feature of the pectin obtained by the proposed method is the increased content of free carboxyl groups and esterified groups with high gel-forming ability. In addition, the obtained pectin is demetallized by the content of metal ions: calcium, iron, magnesium. This allows us to recommend the obtained pectin as an effective enterosorbent for the production of therapeutic and prophylactic nutrition. (56) 1. USSR author's certificate N 1399303, cl. C 08 B 37/06, 1986.

 2. USSR author's certificate N 1675303, cl. C 08 B 37/06, 1991.

Claims (1)

METHOD FOR PRODUCING PECTIN, including preparation of a blend of beet pulp and apple pomace, swelling of the mixture in an aqueous solution of acetic acid, washing with water, hydrolysis with a mixture containing aqueous solutions of hydrochloric and acetic acid, separating the hydrolyzate, cooling and neutralizing it, precipitating 96% pectin ethyl alcohol, its cleaning and drying, characterized in that the mass ratio of beet pulp and apple pomace in the blend mixture is selected within the range of 1: 1 - 9, cellulose phosphate is additionally added to the mixture in t he 2 - 4% of its mass, and hydrolysing the mixture of aqueous solutions of hydrochloric and acetic acid is additionally introduced preheated and maintained at 90 - 95 ^o C for 15 - 25 min whey acidity of 290 - 300 ^o T, wherein the weight the ratio of hydrochloric, acetic acids and lactic acid contained in whey is respectively 1: 0.220 - 0.660: 0.374 - 0.943.

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