Changes In Pectin Research Articles

Pectin Changes in Ripening Cherry Fruit

ABSTRACTPectin solubilization was studied during ripening of cherry fruit. Pectic materials were isolated at specific stages during development. The proportion of alcohol‐insoluble‐material decreased on a fresh weight basis with ripeness, but increased per fruit. Pectic substances were divided into water‐, oxalate‐ and acid‐soluble fractions. The oxalate‐and water‐soluble part increased as acid‐soluble components decreased. Water‐ and acid‐soluble fractions contained many more neutral sugar residues than the oxalate‐soluble fraction. Changes in individual sugars indicated the major alterations were the degradation of galactan and the absence of arabinan solubilization in acid‐soluble pectic substance. Size exclusion chromatography showed absence of pectin depolymerization during ripening, indicating that fruit softening does not depend on pectin depolymerization.

Mechanism of pectin changes during soaking and heating as related to hard-to-cook defect in cowpeas

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of pectin changes during soaking and heating as related to hard-to-cook defect in cowpeasKeshun. Liu, R. Dixon. Phillips, and Kay H. McWattersCite this: J. Agric. Food Chem. 1993, 41, 9, 1476–1480Publication Date (Print):September 1, 1993Publication History Published online1 May 2002Published inissue 1 September 1993https://doi.org/10.1021/jf00033a023RIGHTS & PERMISSIONSArticle Views194Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (581 KB) Get e-Alerts Get e-Alerts

CHANGES IN PECTIN AND HEMICELLULOSE IN `BELLE OF GEORGIA' PEACHES DURING SOFTENING.

The mechanism of softening was studied in a rapidly softening peach cultivar `Belle of Georgia' by assessing changes in pectins and hemicellulose from enzymically inactive cell walls. Cell wall preparations were sequentially extracted with imidazole and sodium carbonate (pectin extracts), and potassium hydroxide (hemicellulose extracts). The pectin extracts were particularly enriched in galacturonic acid, arabiiose and rhamnose, and contained only small amounts of hemicellulose associated sugars. Hemicellulose extracts were enriched in xylose, glucose, mannose, and fucose. More tightly bound hemicellulose fractions contained considerable amounts of pectin associated sugars. The proportion of pectin associated sugars in hemicellulose extracts was greater for cell wall extracts of softened fruit. Some possible relationships between pectin/hemicellulose solubility and fruit softening will be presented. Work was supported by USDA grant 90-34150-5022 and the Oklahoma Agricultural Experiment Station.

Models for the interactions between pectin molecules and other cell-wall constituents in vegetable tissues

In experiments to study the relationships between textural change and chemical changes in pectins of vegetables after different cooking treatments, pectins in the alcohol-insoluble solids (AIS) of the vegetables were fractionated into four groups according to their solubility in different extractants, and their yields were correlated with the firmness of the tissues. Based on the correlations observed for various vegetables, a simple model consisting of five types of basic pectin interactions in the tissues was proposed first. It includes S-type pectin extractable with cold water, A-type pectin extractable with cold chelating-agent solutions, B-type pectin extractable with hot water, C-type pectin extractable with hot chelating-agent solutions, and P-type pectin extractable with hot dilute acid or alkali solutions, among which C-type pectin was obtained by calculation rather than direct determination. It was found later that, in some cases, the amount of C-type pectin thus obtained came out as a negative value, which is apparently unreasonable. We therefore proposed, by speculation, an elaborate model consisting of twelve sub-types of complicated pectin interactions, which are based on the simple model, in order to explain the unreasonable situation resulting from the calculated value of C-type pectin content. Using snap-bean pods as sample, we now present several experiments to support the real existence of some of the complicated pectin interactions previously proposed. The supporting data came from the analysis and comparison of the amounts of bound calcium in the pectin fractions extracted and from the measurement and comparison of the size of pectin molecules extracted before and after further treatment by either heating or calcium removal.

Pectin changes during the development and ripening of eggplant fruits

In developing and ripening eggplant fruits (Semi-round striped, Purple long and Black round), the main pectin fractions, water-, ammonium oxalate-, and alkalisoluble, were estimated up to maturity and ripening. The determinations were made using the m-hydroxydiphenyl assay, which was automated resulting in a rapid and sensitive method to quantitatively determine the pectic substances. For all cultivars studied, total pectic polysaccharides decreased during the initial growth period and after 15 days showed a slightly increasing trend. The concentration of water-soluble pectic substances decreased until 28 days, as did the oxalate-soluble fraction. These two pectin fractions increased during the development period between 28 and 42 days while the alkali-soluble (protopectin) fraction decreased. The increase of protopectin before physiological maturity, and its subsequent decrease with fruit ripening and softening, indicated the involvement of this fraction in the texture maintenance of eggplant fruits.

Changes in nonvolatile acids, sugars, pectin and sugar composition of pectin during peach (Cv. Monroe) maturation

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChanges in nonvolatile acids, sugars, pectin and sugar composition of pectin during peach (Cv. Monroe) maturationGlenn W. Chapman Jr. and R. J. HorvatCite this: J. Agric. Food Chem. 1990, 38, 2, 383–387Publication Date (Print):February 1, 1990Publication History Published online1 May 2002Published inissue 1 February 1990https://doi.org/10.1021/jf00092a008RIGHTS & PERMISSIONSArticle Views420Altmetric-Citations43LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (643 KB) Get e-Alerts Get e-Alerts

Physico‐chemical changes in guava (Psidium guajava L.) during development and maturation

AbstractGuava of the Vietnamese variety is commercially grown in Malaysia. To obtain a better understanding of the fruit, the physical and chemical changes occurring during development and maturation were studied.The weight increase, reduction in hardness, total pectin content, and changes in glucose and ascorbic acid levels showed a sigmoid curve. The maximum weight and glucose increases occurred between weeks 10 and 12. Reduction in hardness, and changes in pectin and ascorbic acid content occurred most between weeks 12 and 14. Reduction in chlorophyll content, and increase in fruit diameter, fructose content and water soluble pectin fraction showed a more linear change. Fructose level was highest among the three sugars (fructose, glucose and sucrose) monitored during maturity. The density of the fruit increased rapidly at the beginning, remained constant between weeks 4 and 12 and then decreased again.The moisture content increased rapidly at first, followed by a more gradual increase and remained constant after week 14. The pH and percentage titratable acidity of the Vietnamese guava fluctuated, being fairly acidic at week 4 (pH 4.5), least acidic at week 10 (pH 5.4) and acidic again on maturity (pH 4.05). The tannin level was high in immature guava but dropped drastically after week 8, and remained at a constant low level after week 10. Soluble pectin increased during development and maturity. Insoluble pectin (NaOH soluble) increased during development but was converted to soluble pectin during maturity (after week 14).

Pectin changes during the development of mango fruit cv Dashehari

SummaryIn the developing mango fruit cv Dashehari, average fruit weight, moisture, Ca, alcohol-insoluble solids (AIS) and the pectin fractions (water, ammonium oxalate and alkali soluble) were estimated up to maturity and ripening. The Ca content decreased in the early stages, but with approaohing maturity became constant. There was a marked increase in AIS until maturity (70;days) and after 100 days decreased markedly in ripe fruit. Water soluble-pectin increased up to ripening but the alkali-soluble fraction decreased after a maximum at 70 days. The ammonium oxalate-soluble fraction was maximal at 70 and 80 days afterr fruit set. Total pectins showed no increase after 70 days except in the ripe fruit. Increasing quantities-of Ca were apparently released into the fruit flesh causing loss of texture and consequent softening.

Pectin changes in the pre‐cooking step of dehydrated mashed potato production

AbstractSome in‐vivo and in‐vitro characteristics of pectin methylesterase (PME) from cell wall and whole potato tuber were determined and its role was elucidated in the pre‐cooking and cooling steps of commercial dehydrated mashed potato production. The isolated cell walls contained 16.3% anhydrogalacturonic acid with a degree of esterification (DE) of 56, and 25% of tuber total PME. Cell wall pre‐cooking in model systems resulted in a DE of 53.2. Native cell wall pectin solubilisation was much less than that of H‐cell walls devoid of metal cations. Calcium but not Mg, supplied as Ca(Mg)‐starches, retarded pectin solubilisation, while Ca‐uptake by retained pectin was high when cooling followed pre‐cooking. Texture measurements of potato slices pre‐cooked, cooled and cooked suggested a firming effect which could be attributed to Ca‐release from gelatinised starch during pre‐cooking, and stabilisation of Cabridges with free COO− groups of cell wall pectin duringcooling. The role ascribed to PME in causing firming is de‐emphasised.

Changes in Chlorophyll and Pectin After Storage and Canning of Kiwifruit

ABSTRACTKiwifruit were harvested and stored at 0°C. Over a 92‐day period fruit were removed from storage, ripened to 13° Brix by holding at 25°C, and canned as slices in a sugar syrup. Changes in the chlorophylls and pectic substances were measured after storage and canning. The concentration of total chlorophyll remained virtually constant during storage and ripening. During the canning process about 90% of the chlorophylls was degraded, the data fitting a first‐order model better than a second‐order model. The total pectin content increased by over 100% during storage and ripening but decreased significantly during canning. A significant inverse relationship between the firmness of unpeeled kiwifruit and the water‐soluble, high‐methoxyl pectin content was derived.

Effects of storage treatments upon the ripening of conference pears

AbstractPreliminary work established the pattern of changes in the amounts and properties of soluble pectic polysaccharides in Conference pears during ripening at 10 °C.Conference pears were harvested on three dates and stored in air at −1 °C and in 2% O2 at −1 °C for various periods. They were ripened on removal from store at 18 °C. Chlorophyll and carotenoid concentrations in the fruit peel and soluble polyuronide concentrations in whole fruit as well as general storage data were recorded.The lag in the ripening of pears at 18 °C after harvesting was abolished by storage at −1 °C. Softening and pectin changes were similar in all stored fruit samples irrespective of picking date, period of storage and whether stored in air or 2% O2. Storage in 2% O2 did retard breakdown slightly, however.The main effect of 2% O2 was that it reduced the rate of destruction of chlorophyll during storage. Higher levels of chlorophyll were found during ripening in fruit which had been stored in 2% O2 than in fruit stored in air.

Maturation of ‘Anjou’ Pears in Relation to Chemical Composition and Reaction to Ethylene1,2

Abstract To study the effect of maturity on ethylene induced ripening, ‘Anjou’ pears were picked at 4 stages of development representing 57%, 71%, 86% and 100% of total growth period. Beginning of a distinct maturation stage in ‘Anjou’ pears was not evident from changes in wt, firmness, soluble pectin, soluble solids, protein N or malic acid. Respiration, ethylene production and softening were differentially affected by ethylene treatment, according to concn applied (0.05-2.0 ppm) and time required for stimulation. Threshold concn affecting these reactions decreased progressively during maturation. Ripening as measured by softening was not dependent on development of the respiratory climacteric. Maturation of the ‘Anjou’ pear appears to involve a reorganization of metabolism preparatory for ripening.

Pectin Changes in the Ripening of Irradiated and Stored Strawberries

SUMMARY: Strawberries of the “Red Gauntlet” variety picked at two different stages of maturation were irradiated with a 60Co source at 200 krads. After irradiation the fruits were stored in a refrigerated cell at a temperature varying from 0 to 3°C and at a R.H. between 85‐90%. During the storage a part of the control berries was irradiated at different times to find out differences in irradiation response at successive stages of ripeness in storage conditions. The effects of irradiation on the pectic substances, pectinmethylesterase activity and anthocyanin content were investigated. In addition, changes in softening and extent of fungal growth were followed. A different response of strawberries irradiated at two different stages of ripeness was found. The different ripeness in storage conditions also influences the radiation response of the strawberries. The possible practical applications of these findings are discussed.

Radiation-induced Calcium Release and its Relation to Post-irradiation Textural Changes in Fruits and Vegetables

Loss in texture is the most characteristic change in fruits and vegetables on exposure to ionizing radiation1–9. Relatively low doses induce extensive softening in tissues. Consideration of the radiation-induced chemical changes in pectins—important structural elements of the middle lamella10—led to the suggestion that their in situ degradation may contribute to softening11. A decrease in protopectin and an increase in the pectin and pectate fractions of pears and peaches irradiated with 300, 600, or 900 krads of γ-radiation have been correlated with textural changes12. Glegg and Kertesz13 considered that degradation of cellulose was probably a major factor in post-irradiation softening.

Texture and Pectin Changes in Canned Apricots

SUMMARYThe influence of ripeness level, heat proeessing, and post‐canning storage on texture and pectin changes in canned apricots was investigated. Important factors influencing canned texture were ripeness level of the fresh fruit and processing time. The canned product gradually softened during storage, while water‐soluble pectin in the syrup increased and proto‐pectin in the fruit decreased. Riper apricots contained less protopectin, and the syrup derived from them contained more water‐soluble pectin. Syrup viscosity gradually increased during storage of canned apricots. The characteristics of pectin were related to the texture of canned apricots.

Effect of Ionizing Radiations on Plant Tissues. III. Softening and Changes in Pectins and Cellulose of Apples, Carrots, and Beetsa

SUMMARYA study was conducted of changes that occur in pectic and cellulose constituents of apple, carrot, and beet tissues as a result of treatment with gamma radiation. In apple tissues, degradation of both these constituents occurred at approximately the dose at which tissue softening could he first demonstrated, and progressed with increasing dose. The degradation of pectins was demonstrated by several criteria, such as the loss of viscosity in the individual fractions, the loss of specific viscosity calculated for a constant uronide or calcium pectate value, and by change in the soluble‐insoluble pectin ratio. Cellulose degradation was characterized by a decrease in the specific viscosity calculated for 0.15% cellulose solutions.Although these findings were corroborated in carrot tissues, the softening of beets does not seem to be as clearly accompanied by such marked changes in pectins and cellulose. Whereas previously published data indicated that beets have a higher softening threshold dose than either carrots or apples, this does not explain the differences found. It is suspected that other factors, such as cell turgidity, are involved in the softening process, and is here responsible for this phenomenon.

Histological and Histochemical Changes in Developing and Ripening Peaches. II. The Cell Walls and Pectins

Reeve, R. M. (U.S.D.A., Albany, California.) Histological and histochemical changes in developing and ripening peaches. II. The cell walls and pectins. Amer. Jour. Bot. 46(4): 241–247. Illus. 1959.—Histological and histochemical observations on developing and ripening clingstone and freestone peaches have revealed that, after cell divisions have ceased in the mesocarp, cell wall thickening and cell enlargement in the mesocarp parenchyma increase until the fruit is nearly full cell size. The cell walls then decrease in thickness as the fruit ripens and softens. Degree of methyl esterification of the pectic substances, as estimated histochemically, remains at about 75–80% in immature fruits during their cell-enlargement phase of growth. Percent of methyl esterification apparently is much lower, or amounts of esterified pectates are very low during the meristematic phases of fruit growth. Just prior to ripening, degree of esterification increases and approaches 100% in hard, ripe fruit at about the same time that the parenchyma cell walls exhibit their greatest thickness or degree of hydration. The degree of esterification of the pectic substances then rapidly decreases and the cell walls become appreciably thinner as the ripening fruit softens. Further relation of these changes in wall thickness, in degree of esterification of the pectins, and in other cell wall carbohydrates to the textural qualities of ripening fruits is discussed. Interpretations concerning cell wall plasticity, cell growth and relation between auxin and changes in pectins also are presented.

HISTOLOGICAL AND HISTOCHEMICAL CHANGES IN DEVELOPING AND RIPENING PEACHES. II. THE CELL WALLS AND PECTINS

Reeve, R. M. (U.S.D.A., Albany, California.) Histological and histochemical changes in developing and ripening peaches. II. The cell walls and pectins. Amer. Jour. Bot. 46(4): 241–247. Illus. 1959.—Histological and histochemical observations on developing and ripening clingstone and freestone peaches have revealed that, after cell divisions have ceased in the mesocarp, cell wall thickening and cell enlargement in the mesocarp parenchyma increase until the fruit is nearly full cell size. The cell walls then decrease in thickness as the fruit ripens and softens. Degree of methyl esterification of the pectic substances, as estimated histochemically, remains at about 75–80% in immature fruits during their cell‐enlargement phase of growth. Percent of methyl esterification apparently is much lower, or amounts of esterified pectates are very low during the meristematic phases of fruit growth. Just prior to ripening, degree of esterification increases and approaches 100% in hard, ripe fruit at about the same time that the parenchyma cell walls exhibit their greatest thickness or degree of hydration. The degree of esterification of the pectic substances then rapidly decreases and the cell walls become appreciably thinner as the ripening fruit softens. Further relation of these changes in wall thickness, in degree of esterification of the pectins, and in other cell wall carbohydrates to the textural qualities of ripening fruits is discussed. Interpretations concerning cell wall plasticity, cell growth and relation between auxin and changes in pectins also are presented.

Effect of Ionizing Radiations on Pectin

The pectic substances play an important role in influencing the firmness, texture, and softening of many plant tissues, particularly fruits and vegetables (1). For this reason a study of the effect of ionizing radiations on pectin was made an integral part of our investigations of the irradiation-induced softening of plant tissues. The present paper reports the results of some model experiments which were designed to give information on the extent of irradiation which causes measurable changes in pectin. Pectin is basically a colloidal macromolecular polymer of anhydro-D-galacturonic acid (1). The changes which occur in macromolecular polymers on exposure to ionizing radiations have been observed in a number of instances, particularly with synthetic polymers and elastomers. It is quite clear that, with respect to the effects of ionizing radiations, macromolecular polymers fall into two categories (2). Compounds of the first group show, on irradiation, crosslinking or increased crosslinking. Polyethylene is a representative of this type of behavior (3). In the second group fall macromolecular polymers which are hydrolytically degraded by ionizing radiations. As far as is known today, naturally occurring polysaccharides like cellulose (4, 5), dextrans (6, 7), starch (8), agar (9), alginic acid (10), various gums (8), and pectins (11, 12) fall into this latter category. The literature contains some observations on the texture changes which occur on the irradiation of plant tissues (13, 14), but only a recent article of Roberts and

Studies on polygalacturonase of certain yeasts

1. 1. Among a considerable number of yeast species, representing nearly all yeast genera, only six were found which were capable of causing certain changes in pectin, when grown in its presence. These six cultures could all be identified with Saccharomyces fragilis (and a variety of this species) and its imperfect form Candida pseudotropicalis, as well as certain varieties of the latter. (See Discussion section.) These organisms cannot use pectin as a source of carbon, but require an added sugar for development. 2. 2. S. fragilis var. No. 351 was used for most of the studies reported herein. When it was grown in the presence of pectin, clarification of the liquid culture media took place with the formation of an amorphous precipitate consisting of about 1% of the pectin added. The jellying power of the pectin is destroyed, but the amount of calcium pectate and alcohol precipitate, obtainable from a clarified solution, is practically unchanged as compared to control solutions. 3. 3. The action was found to be due to an exocellular, nonadaptive, polygalacturonase-like enzyme, free of pectinesterase. The action of this yeast polygalacturonase is characteristic in that pectic acid, when used as a substrate, is only partially hydrolyzed. In contrast to fungus polygalacturonase, the enzyme cannot hydrolyze pectic acid completely to monogalacturonic acid. The velocity constant of the (initially) first-order reaction was found to be 0.196 at 22 °C. and at a pH of 3.40. The optimum pH was approximately 3.5–4.0, and the maximum rate was in the region of 55–60 °C.