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PubMed2002

Changes in cell wall pectins accompanying tomato (Lycopersicon esculentum Mill.) paste manufacture.

The texture of processed tomato products is influenced by the size and solubility characteristics of soluble and particle-bound cell wall polysaccharides they contain. The acidic (pectin) polysaccharides are important contributors to texture because of their gel-forming capability and the fact that they can form aggregates. The present work describes the pectins in ripe tomato fruits and then follows changes in several classes of pectins as the fruits are subjected to hot break and the juice is subsequently concentrated to a 30 degrees Brix paste. Continued processing leads to progressive solubilization and depolymerization of polysaccharides so that the ionically and covalently bound materials that are the major pectin classes of ripe fruit are substantially reduced in amount with the concomitant increase in the more soluble water-soluble pectins of the paste product. Juice content of soluble solids ( degrees Brix) rose steadily as water content was reduced during processing. Juice content of polymeric uronic acids (i.e., pectin) also rose with concentration, but to a lesser degree than the increase in soluble solids. This indicates that processing leads to almost complete pectin depolymerization and/or the alteration of uronic acid structures so that this assay could no longer detect them. It was concluded that reductions in heat input during processing would lead to pastes with greater pectin integrity and enhanced textural characteristics.

Cell Wall↗
PubMed2006

Pectin fraction interconversions: Insight into understanding texture evolution of thermally processed carrots.

In situ changes in pectin fractions for thermally processed carrots were related to textural changes. The texture of pretreated and subsequently thermally processed carrot disks was determined. Alcohol insoluble residue (AIR) was extracted from the pretreated and thermally processed tissues. The AIR was characterized in terms of the degree of methylation (DM) and changes in pectin fractions. Distinct differences in texture and DM were observed during thermal processing. Pretreatment conditions that induced a significant decrease in DM showed better textures. Demethoxylation caused interconversion of pectin fractions, water soluble pectin (WSP) changing into water insoluble pectin [chelator (CSP) and alkali (NSP) soluble pectin]. This process was reversed during cooking accompanied by remarkable alterations in molecular weight (MW) distribution patterns. The WSP depicted polydisperse MW distribution patterns, strongly dependent on the pretreatment condition. Confirmatory results of interconversions of pectin fractions (WSP, NSP) were demonstrated by the MW distribution patterns and neutral sugar profiles. All thermal related transformations of pectin structural parameters were decelerated by lowering the DM.

Cooking↗
PubMed2004

Pectins from the albedo of immature lemon fruitlets have high water binding capacity.

The white part of citrus peel, the albedo, has a special role in water relations of both fruit and leaves from early on in fruit development. In times of drought, this tissue acts as a water reservoir for juice sacs, seeds and leaves. When water was injected into the albedo, free water was undetectable using magnetic resonance imaging. Microscopy showed tightly packed cells with little intercellular space, and thick cell walls. Cell wall material comprised 21% of the fresh albedo weight, and contained 26.1% galacturonic acid, the main constituent of pectin. From this, we postulated that pectin of the cell wall was responsible for the high water-binding capacity of the immature lemon albedo. Cell wall material was extracted using mild procedures that keep polymers intact, and four pectic fractions were recovered. Of these fractions, the SDS and chelator-soluble fractions showed viscosities ten and twenty times higher than laboratory-grade citrus pectin or the other albedo-derived pectins. The yield of these two pectins represented 28% of the cell walls and 62% of the galacturonic acid content of immature lemon albedo. We concluded that, from viscosity and abundance, these types of pectin account for the high water-binding capacity of this tissue. Compositional analyses showed that the two highly viscous pectic fractions differ in galacturonic acid content, degree of branching and length of side chains from the less viscous albedo-derived pectins. The most striking feature of these highly viscous pectins, however, was their high molecular weight distribution compared to the other pectic fractions.

Binding, Competitive↗
PubMed2004

Development and characterization of different low methoxy pectin microcapsules by an emulsion-interface reaction technique.

In the controlled release area, biodegradable microcapsules are one of the most useful devices to deliver materials in an effective, prolonged and safe manner. A new charged film microcapsular carrier system, using three different pectins, is described. The study utilized pectin microcapsules prepared by two encapsulation mechanisms of interfacial reaction explored through interaction of charged droplet-oil-anionic surfactant-calcium or oil-cationic surfactant with negatively charged pectin. A method for drug encapsulation was developed based on the type of pectin, surfactants and emulsification technique. Both types of surfactant, anionic sodium dodecyl sulphate (SDS) and cationic benzalkonium chloride (BzACl) promoted polymer film formation on the oil droplet surfaces, probably through cross-linking and electrostatic interaction, respectively. Microcapsules consisting of pectin as shell and hydrophobic oil as core were characterized. The resulting microcapsules were relatively small particles (d< 3 microm), had high total particle number, specific surface area and drug encapsulation efficiency. They also demonstrated good stability with minimum particle aggregation. Correlation between physicochemical and drug release kinetic parameters were investigated with regard to the effect of pectin macromolecular structure and nature of surfactant used as a counterion in the manufacturing of microcapsules. The release rate of the encapsulated material (prednisolone) in three microcapsules can be controlled by manipulating the conformational flexibility of pectins in the presence of different counterions. As a result, biodegradable pectin microcapsules offer a novel approach for developing sustained release drug delivery systems that have potential for colonic drug delivery.

Anti-Inflammatory Agents↗
PubMed1982

Exploratory studies of lipid-pectin interactions.

This study was undertaken to elucidate the mechanism responsible for the hypolipidemic action of pectin. The experiments reported here were designed to test if direct molecular interactions exist between pectin and lipids. Equilibrium dialysis of pectin and taurocholate showed binding only at high nonphysiological ionic strength. When lipid microemulsions and micelles of low charge density were used, unambiguous proof of binding to pectin were obtained by NMR spectroscopy and gel exclusion chromatography. The results suggest that the interaction in mainly by hydrogen bonds involving the pectin carboxylic moieties. The quantitation of lipid binding by pectin could be established only in presence of polyvalent cations using a membrane filtration technique. Under optimum conditions, pectin can bind four times its weight in lipids. Although the techniques presented here are physical-chemical, the conclusions are highly relevant to bioavailability. These results represent the first successful demonstration of direct lipid-polysaccharide interactions in biochemistry, and they have an obvious bearing on the physiological absorption process. The intestinal binding of dietary and biliary lipids by pectin may be a major mechanism of action of this hypolipidemic polysaccharide. This paper also cells attention to techniques which could be beneficial for the in vitro evaluation of plant fibers.

Aluminum↗
PubMed1989

Neomycin has no persistent sparing effect on vitamin B-12 status in pectin-fed rats.

In the present study, rats were depleted of vitamin B-12 with fiber-free or 5% pectin diets, with or without neomycin. Through use of this intestinal antibiotic reported to "spare" vitamin B-12, we sought to determine if bacterial fermentation of pectin might explain our previous observations of negative effects of pectin on vitamin B-12 status. However, neomycin did not lessen interference by pectin with vitamin B-12 metabolism. Pectin increased urinary methylmalonate and decreased propionate oxidation to a greater extent in the presence than in the absence of neomycin. Also, regardless of the presence of neomycin, the biologic half-life of injected [57Co]vitamin B-12 was 58 d for rats fed the fiber-free diets and only 38 d for rats fed 5% pectin diets. Neomycin delayed early fecal excretion of 57Co but had no persistent effect. Thus, neomycin-sensitive bacteria do not mediate the negative effects of pectin on vitamin B-12 status. Pectin may interfere directly with vitamin B-12 absorption or may stimulate vitamin B-12 uptake or propionate production by microbial species that have adapted to neomycin.

Animals↗
PubMed1989

Dietary pectin shortens the biologic half-life of vitamin B-12 in rats by increasing fecal and urinary losses.

As little as 5% of pectin added to a fiber-free diet elevates urinary methylmalonic acid (MMA) severalfold in vitamin B-12--deprived rats. The present study examines whether increased urinary MMA reflects lower vitamin B-12 status or occurs only because of fermentation of pectin by intestinal bacteria and increased production of propionate, a precursor of MMA. By monitoring urinary and fecal excretion of 57Co after a tracer dose of [57Co]vitamin B-12, we found the biologic half-life of vitamin B-12 to be 59 d for rats fed a fiber-free diet and only 19 d for rats fed a 5% pectin diet. Also, pectin-fed rats oxidized only 12% of a 1-mmol dose of [14C]propionate to 14CO2 in 2 h, whereas rats fed the fiber-free diet expired 33% of the dose. Finally, high urinary MMA persisted even after the removal of pectin from the diet. We conclude that dietary pectin accelerates vitamin B-12 depletion in rats, possibly by interfering with enterohepatic recycling of vitamin B-12. By stimulating microbial propionate production, pectin and other fermentable fibers may also contribute to increased urinary MMA in vitamin B-12 deficiency, but a larger propionate pool does not account for the other effects of pectin on vitamin B-12 status.

Animals↗
PubMed1993

Intestinal solubility and absorption of ferrous iron in growing rats are affected by different dietary pectins.

The effects of pectin structure on iron solubility were examined in vivo and in vitro using pectins differing in degree of esterification (DE) and molecular weight (MW). The pectins prepared differed (in DE and MW, respectively) as follows: P-A (73%, 860,000), P-B (75%, 89,000), P-C (22%, 1,260,000) and P-D (24%, 114,000). Weanling rats were trained to consume a basal diet containing ferrous sulfate as the iron source within 2 h. Food-deprived rats were presented the basal diet or the same diet containing one of the pectins at 80 g/kg diet. One hour after the meal, soluble, insoluble and tissue iron in intestinal segments and serum iron concentration in portal blood were determined and amounts of absorbed iron were calculated. Portal blood iron and calculated absorbed iron were highly correlated (r = 0.97). None of the pectins reduced iron solubility or absorption below that in rats fed the basal diet. Addition of P-B increased the amount of iron absorbed and postprandial serum iron concentration in portal blood. Solubility of ferrous sulfate in vitro was higher in solutions containing pectins than in a cornstarch solution (P < 0.05) and was also higher in diets containing pectin than in the basal diet (P < 0.05). The pectin with the high DE and low MW (P-B) improved iron solubility and absorption of solubilized iron.

Animals↗
PubMed1999

Dietary pectin lowers sphingomyelin concentration in VLDL and raises hepatic sphingomyelinase activity in rats.

There is evidence that cholesterol and sphingomyelin metabolism are interrelated, and thus the hypothesis tested was that dietary pectin, because it can alter hepatic cholesterol metabolism, would also alter hepatic sphingomyelin metabolism. For that purpose, 4-wk-old female Wistar rats were fed a diet without or with pectin (20 g/100 g) up to 21 d. In accordance with previous work, pectin consumption caused a significant (P < 0.001) reduction in hepatic (65%), whole plasma (37%), and VLDL (80%) cholesterol levels. Pectin also significantly reduced VLDL sphingomyelin concentrations (57%), but raised the amount of sphingomyelin in the high density lipoproteins (HDL)-2 fractions (58%), so that the level of sphingomyelin in whole plasma remained unaffected. Pectin did not affect the sphingomyelin concentration in the liver. Pectin consumption did not affect the hepatic sphingomyelin synthesizing enzymes, serine palmitoyltransferase, phosphatidylcholine:ceramide phosphocholine transferase, or phosphatidylethanolamine:ceramide phosphoethanolamine transferase. In contrast, dietary pectin activated both lysosomal (28%) and plasma membrane (26%) sphingomyelinase and thus may have enhanced sphingomyelin degradation. An attempt was made to describe the effects of dietary pectin on sphingomyelin metabolism in terms of altered fluxes through liver and plasma, with whole liver and whole plasma concentrations of sphingomyelin remaining unaffected.

Animals↗
PubMed2000

The human gut bacteria Bacteroides thetaiotaomicron and Fusobacterium varium produce putrescine and spermidine in cecum of pectin-fed gnotobiotic rats.

Pectin is a soluble indigestible polysaccharide that stimulates cecal polyamine formation in rats. Bacteroides and fusobacteria, two numerically dominant bacterial population groups in the large intestine, were found to synthesize in vitro high amounts of spermidine and putrescine. The purpose of this study was to elucidate the effect of pectin on the polyamine production by defined bacterial species in vivo. Germfree male Wistar rats (n = 18) were randomly assigned to one of three treatments: (i) monoassociation with Bacteroides thetaiotaomicron + fiber-free diet; (ii) diassociation with B. thetaiotaomicron + Fusobacterium varium + fiber-free diet or (iii) diassociation with B. thetaiotaomicron + F. varium + fiber-free diet + 10% pectin. The cecal contents of monoassociated rats fed fiber-free diet contained large amounts (1.51+/-0.21 micromol/dry total cecum content) of spermidine which was the major polyamine. The cecum of diassociated rats fed the fiber-free diet contained even higher concentrations of spermidine (2.53+/-0.21 micromol/dry total cecum content) and also putrescine, which was now the dominant polyamine (putrescine 0.32+/-0.28 vs. 3.01+/-0.28 micromol/dry total cecum content; monoassociation vs. diassociation). Pectin consumption by diassociated rats led to an additional increase in the cecal concentrations of all polyamines: putrescine, spermidine and spermine were 40, 37 and 100%, respectively, higher in the diassociated rats consuming the pectin diet than in those consuming the pectin-free diet. Since the microbial counts in the cecum did not differ in the diassociated treatment groups, the elevated concentrations of polyamines observed in the pectin group must have been due to stimulated bacterial polyamine synthesis. The decline of individual polyamines from cecum to feces detected at the end of the study in all treatment groups and the high microbial counts in the cecum and in feces suggest that bacterial polyamines are absorbed in cecum and colon. Pectin stimulates intestinal microbes to synthesize large amounts of polyamines which may be utilized by the host.

Analysis of Variance↗
PubMed2002

Short-term boron deprivation inhibits endocytosis of cell wall pectins in meristematic cells of maize and wheat root apices.

By using immunofluorescence microscopy, we observed rapidly altered distribution patterns of cell wall pectins in meristematic cells of maize (Zea mays) and wheat (Triticum aestivum) root apices. This response was shown for homogalacturonan pectins characterized by a low level (up to 40%) of methylesterification and for rhamnogalacturonan II pectins cross-linked by a borate diol diester. Under boron deprivation, abundance of these pectins rapidly increased in cell walls, whereas their internalization was inhibited, as evidenced by a reduced and even blocked accumulation of these cell wall pectins within brefeldin A-induced compartments. In contrast, root cells of species sensitive to the boron deprivation, like zucchini (Cucurbita pepo) and alfalfa (Medicago sativa), do not internalize cell wall pectins into brefeldin A compartments and do not show accumulation of pectins in their cell walls under boron deprivation. For maize and wheat root apices, we favor an apoplastic target for the primary action of boron deprivation, which signals deeper into the cell via endocytosis-mediated pectin signaling along putative cell wall-plasma membrane-cytoskeleton continuum.

Boron↗
PubMed1998

Polygalacturonase gene expression in ripe melon fruit supports a role for polygalacturonase in ripening-associated pectin disassembly.

Ripening-associated pectin disassembly in melon is characterized by a decrease in molecular mass and an increase in the solubilization of polyuronide, modifications that in other fruit have been attributed to the activity of polygalacturonase (PG). Although it has been reported that PG activity is absent during melon fruit ripening, a mechanism for PG-independent pectin disassembly has not been positively identified. Here we provide evidence that pectin disassembly in melon (Cucumis melo) may be PG mediated. Three melon cDNA clones with significant homology to other cloned PGs were isolated from the rapidly ripening cultivar Charentais (C. melo cv Reticulatus F1 Alpha) and were expressed at high levels during fruit ripening. The expression pattern correlated temporally with an increase in pectin-degrading activity and a decrease in the molecular mass of cell wall pectins, suggesting that these genes encode functional PGs. MPG1 and MPG2 were closely related to peach fruit and tomato abscission zone PGs, and MPG3 was closely related to tomato fruit PG. MPG1, the most abundant melon PG mRNA, was expressed in Aspergillus oryzae. The culture filtrate exponentially decreased the viscosity of a pectin solution and catalyzed the linear release of reducing groups, suggesting that MPG1 encodes an endo-PG with the potential to depolymerize melon fruit cell wall pectin. Because MPG1 belongs to a group of PGs divergent from the well-characterized tomato fruit PG, this supports the involvement of a second class of PGs in fruit ripening-associated pectin disassembly.

Amino Acid Sequence↗
PubMed2000

A methylotrophic pathway participates in pectin utilization by Candida boidinii.

The methylotrophic yeast Candida boidinii S2 was found to be able to grow on pectin or polygalacturonate as a carbon source. When cells were grown on 1% (wt/vol) pectin, C. boidinii exhibited induced levels of the pectin-depolymerizing enzymes pectin methylesterase (208 mU/mg of protein), pectin lyase (673 mU/mg), pectate lyase (673 mU/mg), and polygalacturonase (3.45 U/mg) and two methanol-metabolizing peroxisomal enzymes, alcohol oxidase (0.26 U/mg) and dihydroxyacetone synthase (94 mU/mg). The numbers of peroxisomes also increased ca. two- to threefold in cells grown on these pectic compounds (3.34 and 2.76 peroxisomes/cell for cells grown on pectin and polygalacturonate, respectively) compared to the numbers in cells grown on glucose (1.29 peroxisomes/cell). The cell density obtained with pectin increased as the degree of methyl esterification of pectic compounds increased, and it decreased in strains from which genes encoding alcohol oxidase and dihydroxyacetone synthase were deleted and in a peroxisome assembly mutant. Our study showed that methanol metabolism and peroxisome assembly play important roles in the degradation of pectin, especially in the utilization of its methyl ester moieties.

Alcohol Oxidoreductases↗
PubMed2003

Effects of the soluble fibre pectin on intestinal cell proliferation, fecal short chain fatty acid production and microbial population.

AIM: Although pectin, a dietary fibre, has been suggested to possess some trophic effects on the intestine, the mechanisms involved remain unclear. This study aimed to evaluate the effects of pectin on rat intestinal cell proliferation and the intraluminal environment. METHODS: Control and pectin-fed rats were given a fibre-free elemental diet (ED) and an ED containing 2.5% pectin, respectively. On the 15th day, the length, weight and number of Ki-67-positive cells from each intestinal segment, and the short chain fatty acids (SCFAs) and microbial population in the caecum were measured. Plasma glucagon-like peptide-2 (GLP-2) concentration and GLP-2 receptor (GLP-2R) mRNA levels in the epithelium were also determined. RESULTS: Pectin supplementation resulted in significant increases in the length, weight, and number of Ki-67-positive cells in the ileum, caecum and colon. Although pectin supplementation did not affect the caecal microbial flora that produced SCFAs, the caecal SCFA content was significantly increased. Pectin supplementation also induced an increase in the plasma GLP-2 concentration, but did not affect the GLP-2R mRNA levels in the small intestine. CONCLUSIONS: The increases in the caecal SCFAs and plasma GLP-2 levels induced by pectin supplementation may cause mucosal proliferation in the lower intestinal tract.

Animals↗
PubMed2001

Extrusion/spheronization of pectin-based formulations. II. Effect of additive concentration in the granulation liquid.

PURPOSE: The aim of this study was to improve the formation of spherical pectin pellets by investigating the effect of additive concentration in the granulation liquid on the shape and size of the products as well as by identifying an optimal additive concentration. METHODS: High-methoxylated, low-methoxylated, and amidated low-methoxylated pectin types were evaluated in combination with different concentrations of methanol, ethanol, citric acid, lactic acid, and calcium chloride. Pellets were prepared in a power-consumption-controlled twin-screw extruder, then spheronized and dried. The moisture content of the extrudate was determined, and the final products were characterized by image analysis and sieving analysis. A cloud point test was employed for the identification of an optimal additive concentration. RESULTS: The concentration of additive in the granulation liquid affected the moisture content of the extrudate and the shape, size, and mechanical stability of the pectin pellets. Improvements in the pellet characteristics are dependent on the pectin type employed. The 2 low-methoxylated pectins were more sensitive to concentration changes than was the high-methoxylated type. Above a certain threshold concentration, the quality of the pellets are improved. This additive concentration differs according to type of pectin and type of additive. CONCLUSION: It was demonstrated that there is a concentration-dependent interaction between pectin and substances added to the granulation liquid that can be utilized to improve the formation of spherical pectin pellets.

Calcium Chloride↗
PubMed2003

Effect of dietary pectin on the production of immunoglobulins and cytokines by mesenteric lymph node lymphocytes in mouse colitis induced with dextran sulfate sodium.

The present study explores the dietary effect of pectin on the MLN lymphocyte functions of mice with dextran sulfate sodium (DS)-induced colitis. We found that the immunoglobulin (Ig)A level in mesenteric lymph node (MLN) lymphocytes was high, while the IgE level was lower, in mice fed with pectin than in those fed with cellulose. Interestingly, the fecal IgA concentration of the pectin-fed mice was significantly higher than that of the cellulose-fed mice. The concentrations of interferon-gamma and interleukin (IL)-2 treated with concanavalin A (ConA) were significantly higher in the pectin-fed group than in the cellulose-fed group. Although dietary pectin did not affect the IL-4 and IL-10 levels, the activation-induced IL-4 and IL-10 secretion was lower in MLN cells of the pectin-fed mice than of the cellulose-fed mice following DS-induced colitis. Based on these findings, we propose that the effect of dietary pectin on mice with DS-induced colitis is mediated by the manipulation of Th1 cells. Furthermore, the inhibitory effect of IL-4 and IL-10 by dietary pectin may play an important role in promoting a change in Th1/Th2 balance toward Th1-dominant immunity.

Animals↗
PubMed1983

Effect of pectin on gastric emptying and gut hormone release in the dumping syndrome.

The effect of pectin on gastric emptying, gut hormone release, and symptoms was studied in four patients with dumping syndrome and in two healthy volunteers after ingestion of a hypertonic glucose meal with and without addition of pectin. The initial fraction emptied from the stomach was reduced in the patients, whose symptoms of dumping were abolished or alleviated by pectin. This change of the emptying seems to be caused by a prolonged stomach transit, probably due to the viscous nature of the pectin meal. Pectin had no effect on the gastric emptying of the volunteers. The motor activity of the stomach was not altered by pectin in either the patients or volunteers. In the patients insulin, enteroglucagon, neurotensin, and gastric inhibitory polypeptide rose to higher levels after the glucose meal than after the glucose-pectin meal. The individual differences in the hormone release were considered secondary to the altered gastric emptying produced by pectin.

Adult↗
PubMed1996

Pectin-supplemented enteral diet reduces the severity of methotrexate induced enterocolitis in rats.

BACKGROUND: Administration of methotrexate (MTX) to rats fed an elemental diet results in a high mortality from severe enterocolitis. Previous studies have shown that pectin is an important precursor of substrates for intestinal structure and function and may facilitate intestinal recovery after enterocolitis. The aim of this study is to evaluate the effect of pectin on MTX-induced enterocolitis in rats. METHODS: Rats received intragastric infusion of either 1% pectin-supplemented or pectin-free elemental diet from the beginning of the study via a gastrostomy. On the 4th day animals received either MTX, 20 mg/kg intraperitoneally, or saline injection and were killed on the 7th day for sampling. RESULTS: Pectin supplementation significantly decreased body weight loss, organ water content, and intestinal myeloperoxidase levels and increased mucosal protein, DNA, and RNA content in enterocolitis rats. The intestinal permeability was increased by administration of MTX, and pectin supplementation significantly reversed the increased permeability in the distal small bowel and colon. Pectin supplementation also lowered the magnitude of bacterial translocation, decreased plasma endotoxin levels, and restored bowel microecology. CONCLUSIONS: Pectin significantly decreased MTX-induced intestinal injury and improved bowel integrity.

Animals↗