CHARACTERIZATION OF STJNT'I.OWERPECTINS DEPENDING OlT THE MATURITY

STAGE OF PLANTS

CRISTO KRATTCHANOV andANTON BRATANOFFHigher Institute of Food and FlavourIndustries, Plovdiv, Bulgaria

INTNODUCTION

Stoikof f (1948) found that the sunflowerheads were rich in pectin raw material ex-ceeding 250/6 polyuroni'de content and mightbe applied to the industrial production ofpectin. Stoikof f (1958) established that thesunflower pectin was similar to the ap,ple andcitrus pectin in its properties. Since then anincreasing interest has been ,continuously takenin this new pectic raw material (M ons e1i s e,1954; Qudrat et a1., 1972;P"iaz and Ud-din, 1972; Sabir et al., 1976; Lin et a1.,1976, 1978).

It is known that the pecti,c substances infruits sustained qualitative and quantitativechanges in passing through various physiolo-gical stages (T i s h c h enk o and S ap o zhni-k ov a, 1972 ; R o us e and G r an dtll, lgTB ;Bhattacharyya et a1., 1970). Ttr,e litera-ture provides scanty and inconsistent data onthe yield and the quality ,of sunflower pectinsdepending on the harvest time of sunflowerheads. Andreev (1956) found that the qua-lity of pectic substances in sunflower hôadsincreased from 8.50/6 to r18.80/s with the deve-loprnent of plant and obtained its maximumin full maturity. Upon studying the sunflowerplant in three maturity stages Lùdtke (1961)established that the total amount of pecticsubstances in the whole plant was slightly de-pendent on the development stage (fr,orrr g.b?to 10.98).

According to L ù d t k e, the changes in themethoxyl content were non-essenii,al whilemore important changes v/ere observed in the{egree- of polymerization. Stoikof f (lgbS)showed that the ,degree of esterification andth.e- gelling po\Mer of pectin decreased stronglywith passing from yellow brown to brown ma-turity of sunflower which was c,onfirmed inour later studies (Stoikoff and Krat-ch,an ov, 1966). L in etal, (1975) studiedthreesunflower cultivars in three maturity stagesan'd coneluded that the methoxyl number-ofsuflower pectin \À/as more strongly dependenton the cultivar than the maturity of heads.Campbell et al. (1978), when studying four

sunflower ,cultivars in three developmentstages, confinmed the ,observations of S t o i -k o f f that the degree of esterification of sun-flower pectin decreased with the maturitv ofplant. They found that the watersoluble frac-tion of sunflower pectin did not give firmjetllies while the gelling power of thè oxalate-soluble fraction was 'good an depended sligh-tly on the maturity stage of sunllower heads.These contradictory data and the pro;blem ofindustrial production of sunflowef pectin inour country resulted in ,carrying out- the stu-dies on the effest of the development stage ofsunflower on the pectin content of, sunfl-owerheads and the ôharacteristics of sunflowerpectins.

MATERIALS AND METHODS

Sunflower heads of the cultivar peredovik,crops 1975, 1976 and 1gZZ, harvested in theex_perimental fields at the Vassil Kolarov Agri-cultural Institute in Plovdiv, were used

"forthis study. After harvesting the heads werethreshed to remove the seedi and shredded inpieces of 3-7 cm. The raw material thus ob-tained was dried in a laboratorv forcod draftair oven at b0oC to ,a moisture ôt S-eo7o. tfreheads_ were ground in a laboratory miil andstored in air-tight packages. The ânalysis forpolyuronrde content and degree of esterifi_cation of the raw rnaterials was made bv amodified method of Gee, McComb andMcCready (Gee et a1., lgbS):

The extraction of the pectins was achievedwith 0.50/s oxalic acid in accordance with apreviously described method (Stoikof f andK r a t c l_r ,a_ n o v, 196G), while the precipitationwas carried out with a double volume ôf ethvtalcohol.- The coagulate was repeatedly washédwith ethanol acidified ^with hydrochlbric acid,and finally with 700/o ethànol to neutraireaction.

-The degree of esterification and the purityof the pectic preparations obtained were âeter--mined by neutraiization on a Hinton indicator(Hinton,1940).

49

The gelling power of the pectins obtainedwas estâblished by the firmness of standar'd650/0 sugar jellies accordiqg to the method ,andthe

'equipment of Tarr-B,aker (B a k e r, 1926).

The viscosity nurnbers were evaluated bythe method of

-Deuel (D e u e 1, 1943) using the

Hôppler vis,cosimeter.

. RESULTS AND DISCUSSION

We studied initiatly the changes in the pec-tic substances of sunflower heads in terms ofthe polyuronide content and the degree ofesterification determined by the method ofGee, McComb and McCreadY (G e e et â].,1958). The data are shown in Table 1 as

Table 7

Polyuronide eontent of sunflower heads depentlingon the maturity degree

Table 2

Characteristics of pectic preparations obtained fromsunflower heads in various maturity stages,

"a*or"l-"1 Maturitydegree

Floscules

Early vax

Wax maturityYellow brown

*^!"-i*rrrrq!qr r!J

Yellow brownto brownmaturity

Brown matu-rity

YiCIdolo

poweracc.to

Tarr-Baker

ll

190

190

200

240

220

180

Visco-sity

num-beracc.to

Deuel

2

3

^

5

1.14

1.29

1.44

1.26

0.99

0.9?

SampleNo.

average values for the three crops investigated(19?5;1976 and 19??)- The potryuronide con-ient changed from 190/s in floscules to about2501() at brown maturity passing through m'axi-murà at yellow brown tô 6r'own maturity' Hence,it follows that the accumulation of pectic sub-stances in the sunflower heads occurred gr'a-

dually with the development an'd ripening -to yeilow brown maturity when the tr'eads hadthe"ir large,st volume. The degree of esterifi-cation ofttt" pectic substân'ces contained in theheads decreaied gradually with the develop-ment of the plant from 650/s (in floscules) inthe beginning to bellow 40076 at brown matu-rity. Ii follows from the data that in the ini-tiai period of vitality the plant needed a pectinh,aving more expressed hydrophile propertiesand a-1ower ion exohange capacity. A'decreasein the d,egree of esterification of the pectinwas also -observed at ripening of citrus an'dapples (Tiaschenko and Sqnozb.ni-Ëona, \SlZ; Rouse and Granda11, 1978)'

In a further series of expriments, sunflowerheads of crop 1977 were sr.rbjected to extrac-tion with O.ffi oxalic aci,d. Table 2 shows thecharacteristios of the pectic preparations ob-

50

tained. It is seen tha,t under these conditions65-85% of pectins were extr,acted from theraw material. It is worth noting that the degreeof esterification of the pectins obtained wasgenerally lower than that of the polyrrronideséontained in the heads (Table 1), and in thisinstance it decreased gradually with maturityof plant. The lower values of 'degree of este-rification can be attributed to various reasonssuoh as extraction of the lower esterified partof pectin, partial deesterification under theconditions of extraction, et'c. The igelling po\À/erof pre,parat;ions reached its maximum at y-ell9wbrown- maturity of heads. A strict correlationbetween the viscosity number Z (measure forthe degree of polimenizatlon of pectin) and thegellingf power was not observed, pr'esuma'blyfor the gelling properties depended also oncrther faàtors iuèh âs the degree of esterifica-tion, for instance. It is of great significance forstudying the physiological functions- of thepectin in tfre plant, in our opdnion, that withàdvancing the

-ripeness after wax naaturi'ty Sgviscosity -number decreased nearly in parallelwith lowering the degr'ee of eisterifioation. Itshows th,at processes of pectolysis have startedwhich resulled in decreasing the water uptakeof the cell system, i.e. in lessening the turgurof cells and moreover the active exchangeprocesses in plant. These changes affected alsothe appearance of the sunflower heads-withpassing-from wax maturity to yellow brown andbrown maturity especially, the moisture ,con-

tent of the heads decreased and a s'harp re-duction of their geometric size was observedas well.

The above discussed data also suggested thatin selecting the harvest period of sunflowerheads, it shoul'd be taken into considerationnot only the technological properti'es of thesunflower plant as oleaginous raw materialbut also as a raw material for the production

Maturity degreeof sunflower

heeds

Polyuronidecontent Yo

19.0-20.0

20.0-22.0

2t.0-24.0

22.0-25.0

23.0-27.0

22.0-26.0

Degree ôfesterification

olo

64.0-66.0

60.0-62.0

53.0-59.0

50.0-56.0

41.0-53.0

38.0-48.0

r

crop 197?

Floscules

Early waxmaturity

'Wax maturitYYellow brown

maturityYellow browq

to br,ownmaturity

BrownmaturitY

of pectin. For certain applications of the sun-flower pectin such as gelling agent, thickeneror product for curative and preventive pur-poses, the sunflower should be harvested atyellow brown maturity instead of brown ma-turity as is practised recently in agriculture.

CONCLUSIONS

1. The polyuronide content of threshedsunflower heads varied within 19-2707t pas-sing through maximum at yellow brown tobrown maturity.

2. The degree of esterification of sunflowerhead pectic substances decreased graduallyfrom 66016 to 380/6, being the highest in thèstage of floscules and the lowest in brownmaturity stage.

3. The gelling power of oxalate-extractedpectic preparatjons \M,as dependent on the ma-turity of sunflower he,ads while a trend to-ward increasing to yellow brown maturity wasnoted followed by decreasing.

4. The vis.cosity number of the pectin passedalso through maximum during the develop-ment of sunflower (the highest value \Mas re-ported at wax maturity) while a strict corre-lation between the gelling properties depen-dent o,n the degree of esterification was notobserved.

5. The polyuronide content of sunflowerheads, the physico-,chemical properties and thechemical content of the sunflower pectin weremostly dependent on the maturity stage andto mu'ch lesser extent on the year of culti-vation.

REFERENCES

Andreev K. St., 1956, Pectic substances and che-micelluloses in sunflouer, Nauchni trudovevissh selskostopanski institut Georgi Dimitrov -Sofi,a, Agronomocheski fakultet. 3. 89-100.

Baker G. L., 1926, Jellg strength of pectin jellies,in Eng. Chem. 18, 89-93.

Bhattacharyya G. C., Ghosh J. J.. Bhat-tacharyya K. G., 1970, Pectin changes and

' storage behauiour of fruits during differentcolor stages of maturation, Indian J. Appl. Chem.33, (4),234-237.

Campell S. J., Sosulski F. \M., Sabir M. A.,1978, Deoelopm,ent of pectins in sunflouer stalksand, heads, Cart. J. plant Sci., 58, 863-868.

D e u e 1 H., 1943, Pektin als hochmolekularer Elek-trolgt, J|/Iit.. Gebiete Lebensmittelunters, Hyg. 84,41-51.

Gee M., McCornb E. A., McCready, 19b8,A method for the characterization of pecticsubstances in some fruit and sugarbeet rno,rcs,J. Food Soi.. 23. 72-75.

H i n t o n C. L., û940, Frui,t pectins, Chemical pu-blishing Co., New York, 27-34.

Lin M. J. Y., Sosulski F. W., Humbert E. S.,Downey, R. K., 1975, Distribution dnd com-position of pectins in sunflouser plants, Can.J, Plant Sci., 55, 507-513,

Lin M. J. Y., Humbert E. S., Sosulski F. W.,1976, Ertraction of pecti,ns from sunflowerheads, Can. Inst. Food Sci., Technol. J., S, (2),70-74.

Lin M. J. Y., Sosulski F. W., Humbert E. S.,1978, AciiLic isolation of sunflotoer pectin, Can,Inst. Food Sci., Technol. J. II, 75-77.

L u d t k e M., 1961, Uber die Pektine der Sonnen-blume, Z. Pfl.anzenzùchtung, 45, (B/4), 406-420.

Monselise J. J., Ephraim 4., 1954, Pectinfromsunflouer heads, BuIl. Research Council Israel,4, 44-47.

Qudrat-E-Khuda M., Ikram-Ur-RehmanSiddiqi, Amir S. M., 19?2, Eætraction ofpectic substances from sunflower heacls, pa-kistan J. Sci. Ind. Res., 15, (3), 202-203.

Riaz S., Uddin M., 1972, Polgsaccharide eompo-nents of sunllotner head,s, Part I : lhe pectins,Pakistan J. Sci. Ind. Res., 15, (3), 16?-1?0.

Rouse A. H., Grandall P. G., 19?8, Pectin con-tunt of lime anil lemon peel as eætracteil bAni,tric acid, J. of Food Sci., 43, 72-78.

Sabir N(.4., Sosulski F. W., Campbell S. J.,1976, Polgmetaphosphate and oæalate eætractionof sunJlouer pectins, Agricultural and FoodChemistry, 24, (2), 348-350.

Stoikof f St., 1.948, Uber Sonnenblumenpektin,Mitt.Gebiete Lebensrnittelunters.,, Hyg., 39, (415),292-299.

Stoikof f St., 1958, Zur Chemie und Technologieder Pekiinstoffe aus Sonnenblurnenbôd,en, DieNahrung, 2, 287-296.

Stoikof f St., Kratchanov Chr. G.,'1966, Onthe chemistrg and the technologg of sunflouerpectin (IVth cornmunication), Tr. Sci. Ins. Techn.Super. Ind. Alim., Plovdiv, 13, (2), 287.=30L

Tishchenko V. P., Sapozhnikova, 1972, Qua-Iitatioe characteristics of pectic substances frornuarious plants, Prikladnaya biokhimiya i rnikro-biologiya, 8, (5), 586-590.

CARACTÉRISATION DES PECTINESDU TOURNESOL EN FONCTION DU STADE

DE MATURITE DES PLANTES

Résumé

Sur les modifications de la teneur en Trectine etde ses propriétés au cours de la rnaturation desplantes de tournesol, les avis sont très différents.Le présent ouvrage ex,pose les résultats de l'étude descapitules de la variété Peredovik, récoltés à diffé-rents stades de maturité des plantes, pendant lesannées 1975-1977. La teneur en polyuronides descapitules hachés a varié de 190/e à 27010 la valeurmaximale se trouvant entre la maturité jaune et lamaturité brune.

L'estérification des substances pectiques a diminuégraduellement de 66 à 38%, étant plus irmportante aumoment du remplissage des graines et plus taibleau mom,ent de la 'pleine maturité. La production depectine suit une courbe qui débute avec ,140/6 aumornent du remplissage des graines, atteint 23% pen-dant la période entre la maturité jaune et la rnatu-rité brune et prend après une allure descendante.Jusqu'à ,la maturité brune la pureté des substancespectiques augrnente régulièrernent (9?,8%), tandis quel'estérification baise de 56,4 à 39,7010. La capacité degélification des substances pectiques extraites àl'acide oxalique et coagulées à l'étanol acidifié aug-mente jusqu'à la maturité jaunebrune. La vis,cosité

CI

âtteint Ie plus haut chiffre au cours du stade pâteuxde maturiié. Entre 1â caÈacité de gélification et 1e

degré d'estérification, il n'y a aucune corrélation.Lei conditions climatiques des années des essais onteu une faible ou très faible influence sur la quantitéet les propriétés des pectines.

CARACTERIZACIÔN DE LAS PECTINAS DEGIRASOL EN FUNCIÔN DEL ESTADIO

DE MADUREZ DE LAS PLANTAS

Resûmen

Hay varias opiniones 'diferentes oon respecto a loscambios del contenidt 66 'pectina y de sus rasgos'una vez maduradas las plantas de girasol. En elpresente trabajo se han estudiado capitulos de laespecie Peredovik, recogidos en dif'erent'es estadiosde madures de lap plantas, durante el periodotg75-1977. El ,conterii'do en poliuronidas de los capi-tulos picados variô entre 19 y 27 por ciento, pasando

por el punto mâximo en la fase de entre Ia madurezàmarillâ y la madurez castafia. El grado de esteri-ficacidn de las sustancias pécticas disminuyô gra-dualmente, desde 66 hasta 38 por ciento, llegando aser 10 màs elevado en el periodo de relleno de Iassemillas y 10 màs reducido a la sazôn. La produc-ciôn de pectina persiguiô una curva que partiô desde14 por ciento en la fase de relleno de las semillas yalcanzô 23 por ciento en la fase de entre la rnadurezam,arilla y la madurez castafia y luego emqrez6 adisminuèr. La pureza de las sustancias pécticas au-mentô permanentemente hasta Ia madurez castaf,a(9?,8 por ciento), mientras que el grado de esterifi-caci6n disrninuyô desde 56,4 hasta 39,? por ciento'El poder de gelatinizaciôn de las sustancias pécticas'extiaidas .ott â"ido oxâlico y coaguladas con etanolacidifiâdo fue mâximo en la fase de rnadurez ama-rilla-castafla, mientras que la ligamaza tuvo el rnâyornûmero durante la fase de ùadurez en cera' No se

ha notado correlaciôn entre el poder de gelatiniza-ciôn y el grado de esterificaciôn. Los anos han in-lluido poco o rnuy poco en la cantidad y los rasgos

de las pectinas.