Enchev, N.

Lesichkov, V.

Shtereva, M.

English

Varna Medical University Press: Journals

A STUDY OF T H E SORPTION CAPACITY OF L E C I T H I N MODIFIED NATURAL SORBENT R E L A T I V E TO NATIVE PROTEIN V. Lesichkov, M. Shtereva, N. Enchev Natural mineral sorbents are extensively used in the technology of a great variety of productions such as clarifying juices and wines, bleaching and re-finement of vegetable oils, purification of sewage waters and industrial gases, petroleum products and the l ike . W i t h every passing year the ut i l izat ion of natural sorbents augments, and the scope of their application becomes broad-er. Simultaneously wi th the intensive search for natural sorbents, the meth-ods of chemical activation leading to increased sorption capacity are also improved. Th i s is evident from the studies published by N . K . Nadirov (1973), E . A . Ar ipov (1970), M . A . Kerdivarenko (1975), Y . I . Tarasevich (1975) and F . D . Ovcharenko (1975). Kerdivarenko (1975) and Nadirov (1973) describe also a considerable de-proteinization under the effect of sorbents during the bleaching of vegetable oils. The latter effect has been likewise the subject of extensive studies since the presence of proteins in oils deteriorates their qualities both as foodstuffs and industrial raw materials. As a rule, sorbents are employed in the decolouration of oils following chemical act ivat ion. I n the present work we used a modified natural sorbent for the sorption of a nat ive protein in low concentration from a water solution. Experimental Part The natural sorbent used in native protein sorption is obtained from the "Shashkana" locality near by Varna . Fractionation of the natural sorbent was performed in advance, and the fractions picked up underwent leci thin modi-fication. The latter was carried out after a personal method described in an earlier work. Alcohol lecithin solutions were prepared at the following concen-trations: 0 .03%, 0.05%, 0.07%, 0 . 1 % , 0.3% and 0.5 per cent. After modifi-cation, the samples were subjected to desiccation, tr i turation and preservation in dry place. Thus they were ready for carrying out sorption. Native protein sorption from water solution was conducted under static conditions using two dif-ferent concentrations allowable by the method employed. Model solutions of egg protein at 2.90 mg/lit and 4.25 mg/li t concentra-tion are used, indicated as concentration I and I I . To determine the optimal sorbent quantity five different amounts are used in work, namely 0 . 1 , 0.2, 0.3, 0.4, 0.5 g sorbent per 5 ml protein solution. Test tubes wi th smooth plugs are used and after pouring on the sorbent wi th the solution, the wel l stopped 12 W. Lesichkov, M. Shtereva, N. Enchev Protein Sorption over Modified Sorbent T a b l e 1 Lecitrin concen­tration % sor­bent g/5 ml 0,1 0,2 0,3 0,4 0,5 0,1 0,2 0,3 0.4 0,5 0.03% 0,05% 0,07% 0,1% 0,3% I concentration ^-protein/5 ml 8,120 5,510 2,610 1,740 1,450 12,452 11,506 5,943 3,113 1,981 2,784 1,186 0,580 0,406 0,522 3,280 2,668 1,116 1,914 2,784 2,036 0,870 0,504 0,638 0,696 I concentration 7-protein/5 ml 2,650 0,500 0,125 0,300 0,375 2,300 0,600 0,000 0,500 0,825 4,950 3,300 2,000 1,300 1,223 3,828 0,870 0,667 0 0 5,150 0,825 0,675 0,580 0 3,625 2,215 0,787 0,580 0 4,825 2.500 1,575 0,825 0,325 с % muffle. Diagr. 1. Correlation between the quan­tity of unadsorbed protein from a solu­tion with concentration I , and the con­centration of lecithin applied in the modification of natural sorbent 0,5% 5,220 4,640 3.422 2,900 2,088 9.396 4,188 3,396 2,830 2,264 C% ЛКХГ///С Diagr. 2. Correlation between the quan­tity of runadsobed protein from a solu­tion with concentration I I , and the leci­thin concentration applied in the modifica­tion of natural sorbent A Study of the Sorption Capacity of Lecithin. 13 test tube is shaked for 10 minutes without interruption, twice at five hour intervals. The unadsorbed amount of protein substances in the supernatant l iquid is determined overnight after the method of О. H . Lowry (1951) in pa­ral le l samples of 0.2 ml each. Diagr. 3. Correlation between the quan- Diagr. 4. Correlation between the amount tity of unadsorbed protein with concen- of unadsorbed protein with concentration tration I and the amount ofsorbent used Hand the quantity of sorbent used The obtained results are presented in Table I and diagrams 1, 2, 3 and 4„ Diagram I for concentration I , and diagram 2 fDr qpncantration I I represent the correlation between the amount of unadsorbed protein and the concentra­tion of lecithin applied in the modification of the fractionated natural mine­ra l sorbent whenever different amounts of sorbent are used. Diagram I shows the minimum content of protein substances in sorbents activated, wi th 0.07, 0.1 and 0.3 per cent lecithin. At higher concentrations (Diagram 2) the min i ­mum of the protein content is clearly outlined whene/er sorbent treated wi th 0.1 per cent lecithin is employed. I n sorbents treated wi th 0.5 per cent leci­thin, the adsorption capacity is considerably reduced in either of the model solutions. The adsorption capacity of fractionated unmodified natural sorbent is much lower but at quantity 0.5 g/5 ml it exceeds that of sorbent modified wi th 0.5 per cent lecithin solution. 14 V. Lesichkov, M. Shtereva, N. Enchev Diagram 3 for concentration I , and diagram 4 for concentration I I show the correlalion between unadsorbed protein quantity and sorbent quantity used. The adsorbed protein amount is proportional to the amount of sorbent employed. Upon modification wi th a low concentration lecithin, an insignif­icant rise of the curves is established at 0.4 and 0.5 g/5 ml sorbent. The most adequate dependence is established in sorbents modified wi th 0.07, 0.1 and 0.3 per cent which warrants the assumption that the three concentrations re­ferred to should be accepted as optimal. Discussion Purif icat ion of concentrated protein solutions is not a problem. For the purpose numerous, universal ly known methods have been proposed. However, purification of residual protein quantities wi th low concentration proves ra­ther difficult. Chief goal of the present work is to solve the problem outlined. The obtained results show that the fractionated sorbent from "Shashkana" place near V a r n a , employed at concentration 0.5 g/5 ml (10 per cent), displays a good sorption capacity. Modification wi th lecithin at concentrations ranging from 0.07 to 0.3 per cent leads to a considerable increase in the sorption capa­c i ty , the maximum being recorded at 0.1 per cent lecithin concentration — accounting for 100 per cent purification. Sorbent modified with 0.5 per cent leci thin shows a considerable reduction of sorption capacity. Most probably the modificator in excess covers the active centers and leads to aggcegation. S i m i l a r results were obtained by E . A . Aripov (1970) using sorbents modified v i t h water-soluble polymers. Most of the authors working in this field point out 1 per cent as the optimal concentration during modification. Regarding the quantity of modified sorbent 0.3—0.4 g/5 ml yields the optimal results (6-8). T h i s is an indication that modified samples are more sorbefacient than unmodified ones, and therefore their ut i l izat ion is justified. Since modification does not require special equipment and is readily executed, the substitution of imported sorbents by lccal ones is allowed. R E F E R E N C E S 1. Л е с и ч к о в , В л. , X . В е p а н и, H . Е н ч е в , Г. Й о в к о в . V научна сесия на Медицинския факултет — Варна, 1973, св. I I , 56—60. — 2. А р и п о в, Е. А . Природные минеральные сорбенты, их активирование и модифицирование, изд. "Фан" УзССР, Ташкент, 1970. — 3. К е р д и в а р е н к о , М. А. Молдавские природные адсорбенты и технология из применения, изд. «Картя молдовеняске», Кишинев, 1975. — 4. Н а д и р о в , Н. К. Теоретические основы активировании и механизма действия природных сорбентов в процессе осветления растительных масел. Пищевая промышле-ность, 1973. — 5. Т а р а с е в и ч , Ю . И., Ф. Д . О в ч а р е н к о . Адсорбция на глинистых минералах изд. «Наукова думка», Киев, 1975. — 6. L о w r y, О. Н. e t al. J. Biol.rchem., 199, 1951, 265. A Study of the Sorption Capacity of Lecithin. 15 ИЗУЧЕНИЕ СОРБЦИОННОЙ СПОСОБНОСТИ МОДИФИЦИРОВАННОГО ЛЕЦИТИНОМ ПРИРОДНОГО СОРБЕНТА ПО ОТНОШЕНИЮ К НАТИВНОМУ БЕЛКУ Вл. Лесичков, М. Штерева, И. Енчев Р Е З Ю М Е Изучена возможность сорбирования белков модифицированного лецити­ном природного минерального сорбента из м. „Шашкъна" , около Варны. Д о того к а к произведена модификация, он фракционирован 0,03, 0,05, 0,07 0,1, 0,3 и 0,5% спиртовыми растворами лецитина. Д л я сорбции при статических условиях использованы модельные рас­творы яичного белка с концентрациями 2,90 mg/1 и 4,25mg/l. Полученные результаты представлены на одной таблице и четырех диаграммах. Установлено, что модифицированные 0,07 д о 0, 3% лецитином сорбенты показивают повышенную сорбционную способность. Модифицированный 0,5% лецитином сорбент значительно повышает свою сорбционную способность. I 

A STUDY OF THE SORPTION CAPACITY OF LECITHIN MODIFIED NATURAL SORBENT RELATIVE TO NATIVE PROTEIN

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A STUDY OF THE SORPTION CAPACITY OF LECITHIN MODIFIED NATURAL SORBENT RELATIVE TO NATIVE PROTEIN

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