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PubMed1993

Dietary non-starch polysaccharides interact with cholesterol and fish oil in their effects on plasma lipids and hepatic lipoprotein receptor activity in rats.

Male rats were fed the non-starch polysaccharides pectin, methylcellulose or guar gum with corn oil or with 60% of the corn oil replaced by fish oil. They were also fed these diets with or without cholesterol (+ cholic acid). Plasma total cholesterol concentration was higher overall in rats fed cholesterol and lower in those fed fish oil or fish oil + cholesterol. Plasma triacylglycerols were lower in rats fed fish oil with or without cholesterol. Hepatic LDL receptor activity was higher overall in rats fed fish oil or fish oil + cholesterol than in those fed cholesterol. Liver HDL receptor was lower overall in rats fed fish oil or cholesterol. Type of non-starch polysaccharide influenced these dietary effects so that in cholesterol-fed rats plasma cholesterol was highest in those fed methylcellulose, intermediate in those fed guar gum and in those fed pectin was unchanged from concentrations in rats fed pectin without cholesterol. Fish oil feeding lowered plasma cholesterol concentration in rats fed pectin or methylcellulose but not in those fed guar gum. Plasma triacylglycerols were lower in rats fed fish oil and all three non-starch polysaccharides, but concentrations were similar in rats fed pectin + fish oil + cholesterol and in those fed pectin. In rats fed methylcellulose + cholesterol and any non-starch polysaccharide + fish oils, HDL receptor activity was uniformly lower than in rats fed pectin, methylcellulose or guar gum. Low density lipoprotein receptor activity was higher in rats fed pectin + fish oil or pectin + fish oil + cholesterol than in rats fed pectin.

Animals↗
PubMed2006

Intestinal morphology and enzymatic activity in newly weaned pigs fed contrasting fiber concentrations and fiber properties.

The main objective of this study was to determine the effect of fiber source and concentration on morphological characteristics, mucin staining pattern, and mucosal enzyme activities in the gastrointestinal tract of pigs. The experiment included 50 pigs from 10 litters weaned at 4 wk of age (BW 8.6 +/- 1.4 kg) and divided into 5 treatment groups. Diets containing fiber of various physico-chemical properties and concentrations were formulated to contain 73, 104, or 145 g of dietary fiber/kg of DM. The diets were based on raw wheat and barley flours. Pectin and barley hulls, representing soluble and insoluble fiber sources, respectively, were used to increase the fiber concentration. The pigs were fed the experimental diets for 9 d, and then the pigs were euthanized and the entire gastrointestinal tract was removed. Tissue samples were taken from the mid and distal small intestine and from the mid colon. Inclusion of pectin in the diets significantly decreased (P < 0.001) ADFI and ADG compared with pigs fed no pectin. The villi and the crypts were shorter in pigs fed pectin-containing diets, but the villous height/crypt depth ratio was unaltered. Pectin significantly decreased the area of mucins in the crypts of the small intestine, indicating that the pigs fed the pectin-containing diet would probably be more susceptible to pathogenic bacteria, although this cannot be separated from the impact on ADFI. The lectin-binding pattern of the intestinal mucosa was unaffected by diet. The activity of lactase and maltase was increased in pigs fed diets with high fiber content, whereas sucrase activity was increased in pigs fed the pectin-containing diets. The activity of the peptidases, aminopeptidase N and dipeptidylpeptidase IV, was increased when feeding high fiber diets, whereas the activity of gamma-glutamyl transpeptidase remained unaffected by the experimental diets. In conclusion, the reduced feed intake observed with the pectin-containing diets could explain the lower villous height and crypt depth observed in this study. However, direct effects of pectin also are possible, and thus further study is warranted. Feeding pigs high insoluble fiber diets improved gut morphology by increasing villi length and increased mucosal enzyme activity when compared with pigs fed pectin-containing diets. The mucin content as determined by staining characteristics suggests that pigs fed high insoluble fiber diets might be better protected against pathogenic bacteria than pigs fed diets high in soluble fiber.

Animal Feed↗
PubMed2000

Preheating effects on the textural strength of canned green beans. 1. Cell wall chemistry.

Variable preheating conditions allowed the modification of the firmness of two green bean cultivars after processing. The aim of this study was to elucidate the biochemical basis of this phenomenon and to relate pectin differences to different inherent firmness of two cultivars. The preheating temperature, which resulted in the highest retention of firmness after sterilization, corresponded with the optimal temperature for pectin methylesterase activity. After this preheating treatment, there was an overall reduction of the degree of methylation of the cell wall pectin. In addition, the yields of the buffer and chelator soluble fractions, as well as their average molecular mass, were higher after sterilization. Firmness differences between the two cultivars seemed to be related to the degree of methylation, the degree of acetylation, and the total amount of pectins. Preheating of green beans affects texture after sterilization most likely by demethylation of pectin by pectin methylesterase thereby (i) decreasing the beta-eliminative degradation of pectin and (ii) increasing the capacity of pectin to form Ca(2+)-mediated complexes.

Carboxylic Ester Hydrolases↗
PubMed2003

Isolation and properties of pectinases from the fungus Aspergillus japonicus.

Using anion-exchange chromatography on different carriers and phenyl-Sepharose hydrophobic chromatography, five pectolytic enzymes were isolated from the culture liquid of a mutant strain of Aspergillus japonicus: two endo-polygalacturonases (I and II, 38 and 65 kD, pI 5.6 and 3.3), pectin lyase (50 kD, pI 3.8), and two pectinesterases (I and II) with similar molecular weights (46 and 47 kD) and the same pI (3.8). The pectinesterases apparently represent two isoforms of the same enzyme. All purified enzymes were homogenous according to SDS-PAGE and polyacrylamide gel-IEF, except for endo-polygalacturonase II that gave two bands on isoelectric focusing, but one band on electrophoresis. All enzymes had maximal activity in an acid medium (at pH 4.0-5.5). The pectin lyase and pectinesterase were stable at 40-50 degrees C. The thermal stability of both endo-polygalacturonases was much lower (after 3 h of incubation at 30 degrees C, endo-polygalacturonases I and II lost 40 and 10% of the activity, respectively). The activity of endo-polygalacturonases I and II towards polygalacturonic acid strongly depended on NaCl concentration (optimal concentration of the salt was 0.1-0.2 M); the enzymes were also capable of reducing the viscosity of pectin solution, but rather slowly. The pectin lyase had no activity towards polygalacturonic acid. The activity of the pectin lyase increased with increasing degree of methylation of pectins. Both endo-polygalacturonases demonstrated synergism with the pectinesterase during the hydrolysis of highly methylated pectin. On the contrary, in the mixture of pectin lyase and pectinesterase an antagonism between the two enzymes was observed.

Aspergillus↗
PubMed1967

Pectic polysaccharides of growing plant tissues.

1. The polysaccharide compositions of the cell walls of sycamore cambium and sycamore callus tissue have been analysed and found to be directly comparable. 2. Electrophoretic analyses of the whole pectins prepared from actively growing callus and cambial tissue have shown that these preparations contain, in addition to the neutral and weakly acidic components present in apple fruit, a strongly acidic polygalacturonic acid component. 3. The weakly acidic component of all the pectins was directly comparable with that of the pectinic acid of apple fruit. 4. The components of the whole pectin of sycamore callus tissue have been partially purified and analysed. The neutral and weakly acidic components also found in apple fruit were isolated. 5. The pattern of the composition of the neutral sugars present in the pectins of actively growing tissues of cambium and callus has been compared with those present in apple-fruit pectinic acid. 6. The presence of rhamnose linked as galacturonosyl-(1-->2)-rhamnose has been found in sycamore whole pectin. 7. The difference in the pectins of callus, cambium and fruit appears not to be that of species difference but is more characteristic of the nature of the growth and growth conditions of the cells. This is discussed in relation to the problems of the control and mechanism of plant-cell growth and differentiation.

Arabinose↗
PubMed2006

Calcium pectate chemistry controls growth rate of Chara corallina.

Pectin, a normal constituent of cell walls, caused growth rates to accelerate to the rates in living cells when supplied externally to isolated cell walls of Chara corallina. Because this activity was not reported previously, the activity was investigated. Turgor pressure (P) was maintained in isolated walls or living cells using a pressure probe in culture medium. Pectin from various sources was supplied to the medium. Ca and Mg were the dominant inorganic elements in the wall. EGTA or pectin in the culture medium extracted moderate amounts of wall Ca and essentially all the wall Mg, and wall growth accelerated. Removing the external EGTA or pectin and replacing with fresh medium returned growth to the original rate. A high concentration of Ca2+ quenched the accelerating activity of EGTA or pectin and caused gelling of the pectin, physically inhibiting wall growth. Low pH had little effect. After the Mg had been removed, Ca-pectate in the wall bore the longitudinal load imposed by P. Removal of this Ca caused the wall to burst. Live cells and isolated walls reacted similarly. It was concluded that Ca cross-links between neighbouring pectin molecules were strong wall bonds that controlled wall growth rates. The central role of Ca-pectate chemistry was illustrated by removing Ca cross-links with new pectin (wall "loosening"), replacing vacated cross-links with new Ca2+ ("Ca2+-tightening"), or adding new cross-links with new Ca-pectate that gelled ("gel tightening"). These findings establish a molecular model for growth that includes wall deposition and assembly for sustained growth activity.

Calcium↗
PubMed1999

[Dietary fiber inhibits the incidence of hepatic metastasis with the anti-oxidant activity and portal scavenging functions].

Dietary fiber is described as the proportion of plant foods not digested in the human small intestine. Among the various kinds of pectin, apple pectin exerts a bacteriostatic action and therefore may change the composition of the intestinal flora. The diet supplemented with 20% apple pectin significantly decreased the number and the incidence of AOM-induced colon tumors in rats. The prostaglandin E2 (PGE2) level in the distal colonic mucosa and blood of portal vein was lower in rats fed 20% pectin than those fed the basal diet. The ability of apple pectin to decrease PGE2 was dose-dependent and those results suggest an anti-inflammatory effect in the bowel. Rats fed apple pectin showed a significantly lower incidence of hepatic metastasis than those fed the basal diet. To determine whether the anti-inflammatory effect of Lactobacillus on hepatic metastasis model same as apple pectin, Lactobacillus casei was selected. Metastatic nodules were significantly reduced, especially in the group receiving pretreatment. Apple pectic oligosaccharides with small molecular weights showed highly inhibitory effects on hypoxanthin-xanthin oxidase and ferrous sulfate-hydrogen peroxide. The scavenging activity of apple pectic oligosaccharides was suitable and accelerated at high temperatures (120 degrees C, 30 min.). Apple pectin and Lactobacillus have a scavenger effect in the intestinal digestion and portal circulation system as an anti-inflammatory food and have very important function for the prevention of hepatic metastasis.

Animals↗
PubMed1997

Regulation of apolipoprotein B-containing lipoproteins by dietary soluble fiber in guinea pigs.

Dietary soluble-fiber sources such as pectin, guar gum, or psyllium decrease plasma concentrations of low-density-lipoprotein (LDL) cholesterol in guinea pigs by distinct mechanisms, including increases in LDL apolipoprotein (apo) B turnover and/or decreases in LDL apo B flux (J Lipid Res 1995; 36:2394-404). The present studies were undertaken to test whether changes in the rates of very-low-density lipoprotein (VLDL) apo B secretion, VLDL conversion to LDL, and hepatic uptake of VLDL were related to the cholesterol-lowering actions of these soluble fibers. Guinea pigs were fed (by wt) 12.5% pectin, 12.5% guar gum, 7.5% psyllium, or a control diet containing cellulose as the fiber source. Plasma cholesterol concentrations were significantly lower in guinea pigs fed pectin, guar gum, and psyllium by 42%, 46%, and 35%, respectively (P < 0.001), compared with those animals fed the control diet, whereas plasma triacylglycerol concentrations were lower only with guar gum intake. The secretion rate of triacylglycerol, determined after Triton was injected to block VLDL catabolism, was not different among dietary treatment groups whereas the secretion rate of apo B was lower with pectin, guar gum, and psyllium intakes (P < 0.01). In addition, pectin, guar gum, and psyllium significantly altered the composition of newly secreted VLDLs by increasing the number of triacylglycerol and phospholipid molecules in the secreted lipoprotein, indicating the presence of larger nascent VLDLs. In contrast, the average particle diameter of mature VLDLs as determined by electron microscopy was smaller in the dietary soluble-fiber groups in the following order: pectin < psyllium < guar gum. Plasma lecithin-cholesteryl acyltransferase and cholesteryl ester transfer protein activities were lower with intake of pectin, guar gum, and psyllium (P < 0.01). Injection of radiolabeled lipoproteins indicated that pectin, guar gum, and psyllium intakes resulted in more rapid VLDL and LDL apo B turnover and lower LDL apo B flux in guinea pigs fed guar gum and psyllium. These results suggest that the secretion rate of apo B, compositional changes in lipoproteins occurring in the intravascular compartment, and up-regulation of LDL receptors-associated with faster LDL apo B turnover rates-are secondary metabolic responses induced by dietary fiber that contribute to the lowering of plasma cholesterol concentrations.

Animals↗
PubMed1986

Electrostatic effects and the dynamics of enzyme reactions at the surface of plant cells. 1. A theory of the ionic control of a complex multi-enzyme system.

A theory is proposed to explain the physical bases of the ionic control of the activity of an enzyme system, located on a plant cell surface, and probably involved in cell-wall synthesis and extension. The model, which is based on various previously published experimental results, involves several assumptions: a cell-wall pectin methyl esterase de-esterifies pectins and thus creates the fixed negative charges of the cell wall; various enzymes incorporate uncharged carbohydrates in cell-wall material; cell-wall extension implies the sliding of cellulose microfibrils; the enzymes responsible for carbohydrate incorporation are activated by protons in the pH range 4-8 and have very similar pH dependencies: the cell-wall pectin methyl esterase is inhibited by protons in the same pH range. The mathematical derivation of this model, written in the form of a hypercycle, indicates that it is equivalent to a set of two antagonistic enzyme reactions: an enzyme reaction conditioned by pectin methyl esterase which results in the increase of fixed charge density of the cell wall; a number of 'growth enzymes', which produce extension and building up of the cell wall and therefore a decrease of charge density. The mathematical study of this model shows it may display a very high co-operativity of its response to slight changes of pH. This cooperativity means that the cell wall charge density may dramatically increase or decrease, within a very narrow pH range. The steep response of this system appears to be the direct consequence of different pH sensitivities of pectin methyl esterase and of the other cell-wall enzymes involved in cell growth. Calcium, which tightly binds to the cell wall, may diminish or even suppress this abrupt charge transition. This model suggests a novel theory of the ionic control of cell-wall expansion. The very basis of this theory is the existence of an electrostatic potential difference, delta psi, between the inside and the outside of the cell wall. When this delta psi value is large, the local proton concentration is high. Therefore the enzymes involved in cell wall extension and building up are active, but pectin methyl esterase is not. Therefore, the cell wall extends and the charge density decreases. The delta psi value then declines, as well as the local proton concentration. Under these conditions, the pectin methyl esterase becomes activated, whereas the 'growth enzymes' are not. This activation of pectin methyl esterase restores the initial, or an even higher, electrostatic potential difference, which in turn results in a decrease of local pH.(ABSTRACT TRUNCATED AT 400 WORDS)

Calcium↗
PubMed1982

In vitro inhibition of pancreatic enzyme activities by dietary fiber.

Trypsin, amylase, lipase and phospholipase activities were assayed in buffer solutions and in human duodenal juice after incubation with different types of dietary fiber. In buffer solutions, trypsin activity was slightly reduced and amylase activity heavily reduced by pectin of low methylic esterification (LM pectin). Lipase activity was markedly reduced by LM pectin and also moderately reduced by pectin of high methylic esterification (HM pectin). Phospholipase was hardly influenced at all by fiber. Activities of pancreatic enzymes in human duodenal juice were examined after in vitro incubation with pectins, guar gum, wheat bran and ispaghula. Ispaghula did not affect the enzymes except for lipase activity, which was moderately inhibited. The other fiber preparations examined reduced amylase activity by 35-100% at fiber concentrations of up to 1.5 g%, lipase by 40-95% and trypsin by 40-85%. LM pectin had the strongest inhibitory effect among the different fiber preparations studied. Phospholipase activity was only influenced by the pectins, which caused a 75% reduction. It is concluded that dietary fiber of different kinds has the capacity to inhibit pancreatic enzyme activities. This inhibitory effect is dependent on the type of fiber and differently affects the different enzymes. Further, the inhibition seems to be more pronounced when exerted in human duodenal juice than in conventional buffer systems.

Buffers↗
PubMedDate not supplied

Evaluation of filamentous fungi and inducers for the production of endo-polygalacturonase by solid state fermentation.

Aspergillus oryzae CCT 3940, Aspergillus awamori NRRL 3112 and a Trichoderma sp.) were compared for their capacity to produce endo-polygalacturonase (endo-PG) in solid state fermentation. Maximum pectinolytic activity was reached in 72 h of growth, the best two fungal strains being A. niger T0005007-2 and A. oryzae CCT 3940. Three types of commercial purified pectin and four of unprocessed pectin (tangerine, orange, Tahiti lime and sweet lime rind) were used to assess the effect of pectin on the production of endo-PG by A. niger T0005007-2. Maximum pectinolytic activity was achieved using 6 and 10% (w/w) of purified pectin as inducer. Depending on the origin of the commercial pectin used as inducer, maximum endo-PG levels varied from 223 to 876 units per gram of dry medium (one endo-PG unit (U) was defined as the quantity of enzyme which caused a reduction in viscosity of 50% in a 1% w/v solution of pectin in 30 min), indicating that care should be taken when choosing this component of the medium. When the crude pectins were used as inducers at the same concentration as purified pectin, maximum endo-PG activities were 250-300 units/g. However, by increasing the amount of Tahiti lime rind to 50% (w/w) maximum endo-PG was 919 U/g, thus opening up the possibility of a low cost medium for endo-PG production.

Aspergillus↗
PubMed2000

Interactions of flavor compounds with pectic substances.

Investigation has been conducted using equilibrium dialysis on the sorption of flavor compounds (FC) in solutions of low- and high-esterified pectinates (LEP and HEP, respectively). The compounds include 2-acetyl pyridine, 2,3-diethyl pyrazine, 2-acetyl thiophene and some normal 2-ketones. A method of direct gas chromatographic analysis has been developed for the determination of the FC in aqueous solutions at concentrations as low as 10(-3)% v/v. Additional information was obtained by the analysis of circular dichroism (CD) and apparent molar heat capacity. The results indicate: (1) In LEP solutions, sorption of normal aliphatic 2-ketones with chain length greater than C6 presumably proceeds via van der Waals interactions between alkyl groups of the 2-ketone and hydrophobic regions of the pectinate. The sorption increases with increased alkyl chain length. The Gibbs energy of the methylene group transferring from the solvent to the LEP solution is found to be 1.8 kJ/mol for 2-ketones at C7-C9. (2) In acidic media, binding of heterocyclic FC with pectinates mostly proceeds via hydrogen bonding involving the hydrogen atoms in undissociated carboxyl groups in the pectinate macromolecules. It can also be affected by the self-association of the pectinate macromolecules, depending on pH and pectinate concentration. (3) Under neutral conditions, the presence of Mg2+, Ca2 and Zn2+ ions or the formation of the calcium-pectinate gel network has little effect on the sorption of 2-ketones with the LEP. However, in acidic media, metal ions inhibit the sorption of FC through hydrogen bonding. The sorption of 2-octanone in acidic media depends extremely on Ca++ concentration by the correlationship with changes in the structure of LEP solutions in terms of apparent molar heat capacity.

Algorithms↗
PubMed2003

Isolation and characterisation of the homogalacturonan from type II cell walls of the commelinoid monocot wheat using HF-solvolysis.

In contrast to the typical type I cell wall of the dicot plants, the type II cell wall of the commelinoid monocot plants is known to be relatively poor in pectins. Assuming a critical role for the remaining pectins in terms of cell wall architecture and/or as a reservoir of signalling molecules, we have compared different protocols for the isolation of the main pectin polymer, homogalacturonan, from wheat leaf cell walls. Pectin was detected in these cell walls immunochemically using the monoclonal antibodies JIM5 and JIM7, and biochemically by monosaccharide analysis. The Ca(++)-chelators CDTA and imidazole extracted a pectin rich fraction from isolated cell walls which was however contaminated with significant amounts of hemicelluloses. Pretreatment of the cell walls with anhydrous hydrogen fluoride at controlled low temperatures followed by HF/ether- and water-extraction prior to imidazole-extraction of pectins yielded a purer homogalacturonan fraction. The near absence of rhamnosyl residues proved that the isolated homogalacturonan fraction was free of rhamnogalacturonans. If HF-solvolysis was performed at -23 degrees C, the resulting homogalacturonan had a degree of methyl esterification identical to that of the pectins in the initial wheat cell wall. The antibodies JIM5 and JIM7 as well as PAM1 and LM5 proved that the isolated homogalacturonan had a low methyl ester content, was polymeric and free of galactan side chains. We can thus isolate native homogalacturonan from the type II wheat cell walls with the original in muro pattern of methyl esterification still intact, to further investigate e.g., its degradability by plant or microbial pectic enzymes.

Cell Wall↗
PubMed2000

Influence of fiber fermentability on nutrient digestion in the dog.

Eight mature dogs (17.2 +/- 0.2 kg) surgically fitted with ileal T-cannulas were used in a replicated 4-x-4 Latin-square-design experiment to evaluate nutrient disappearance at the terminal ileum and through the digestive tract. Two fiber types, cellulose, a crystalline, slowly fermented fiber, and pectin, a soluble, rapidly fermented fiber, were fed in different increments, and the effects on nutrient availability were assessed. Treatments included 1) 100% cellulose, 2) 66% cellulose and 33% pectin, 3) 66% pectin and 33% cellulose, and 4) 100% pectin. Fiber was added at 10% of diet dry matter (DM). Diets were fed at 100% of ME for maintenance and offered at 0730 and 1730 h. All periods were 21 d, which included 3 d of diet transition and 7 d of adaptation. Daily DM intake was 210 +/- 5 g. Total tract and large-intestine DM digestibility increased linearly (P < 0.01) with increased pectin. These changes in DM digestion were largely the result of changes in fiber digestion. Fermentation of total dietary fiber in the large intestine went from less than zero to 39% of ileal flow (linear, P < 0.01). Total-tract crude-protein digestibility decreased linearly (P < 0.01) with increased pectin. This study demonstrated that fiber fermentability significantly affects digestion in the dog. Increasing fermentable fiber increased the digestion of DM and energy. However, increased fiber fermentability inversely affects crude protein digestibility. The lower crude-protein digestibility could be attributed to larger microbial protein excretion as a result of greater fermentation of pectin versus cellulose.

Ammonia↗
PubMed2007

Microstructure of beta-lactoglobulin/pectin coacervates studied by small-angle neutron scattering.

Small-angle neutron scattering (SANS) has been used to investigate the microstructure of beta-lactoglobulin/pectin coacervates prepared by different initial protein/polysaccharide weight ratio (r), sodium chloride concentration (C(NaCl)), and pectin charge density. The higher r and higher pectin charge density lead to higher scattering intensity at small q range (0.007 Angstrom(-1) < q < 0.02 Angstrom(-1)), suggesting that the charges of pectin chains are screened significantly by the binding of oppositely charged protein molecules, leading to a tighter aggregation of pectin chains. On the other hand, the appearance of a shoulder peak at intermediate q range (0.04 Angstrom(-1) < q < 0.2 Angstrom(-1)) is used to interpret the formation of protein domains in beta-lactoglobulin/pectin coacervates. At C(NaCl) = 0.1 M, the coacervate of beta-lactoglobulin and pectin A does not show a shoulder peak at intermediate q range at r = 10:1, suggesting that protein molecules are separately bound on pectin chains. However, a shoulder peak appears at intermediate q range at r = 20:1 and 30:1, and the average protein domain size estimated from the shoulder peak position is 7.2 and 8.5 nm, respectively, for these two coacervates. When C(NaCl) increases from 0.05 to 0.2 M, the shoulder peak shifts toward smaller q and becomes broader, indicating that the addition of a higher amount of salt leads to a more heterogeneous coacervate structure. Pectin B with a lower linear charge density favors the formation of larger protein domains. The formation of protein domains in beta-lactoglobulin/pectin coacervates is partially ascribed to the self-aggregation of beta-lactoglobulin molecules. Two kinds of microstructures of beta-lactoglobulin/pectin coacervates with and without observable protein domains have been proposed.

Algorithms↗
PubMed1965

APPLE FRUIT PECTIC SUBSTANCES.

1. The pectic substances of apple have been extracted and separated into a pure pectinic acid and a neutral arabinan-galactan complex by precipitation of the acidic component with ethanol and with cetylpyridinium chloride. 2. The composition of the fractions has been determined. The pectinic acid contained galacturonic acid, arabinose, galactose, rhamnose, xylose and several trace sugars. 3. Transelimination degradation of the pectinic acid gave rise to two components completely separable by zone electrophoresis and by Sephadex gel filtration. Analysis of these components confirmed that the pectinic acid molecules contained long chains of esterified galacturonosyl residues, but showed in addition that more neutral portions containing a high proportion of arabinofuranose residues were attached to them. 4. The identification of rhamnose, galactose and xylose in aldobiouronic acids obtained from a partial hydrolysate of pectinic acid has shown that these sugars are covalently linked in the molecule, and it is suggested that the galacturonosyl-(1-->2)-rhamnose link is a general feature of pectinic acid structure. 5. The possible biological significance of pectinic acid structure has been discussed. 6. The arabinan-galactan complex contained nearly equal quantities of arabinose and galactose residues and some of its physical properties have been investigated.

Arabinose↗
PubMed1978

Urinary ascorbic acid excretion in the human as affected by dietary fiber and zinc.

The objective of the project was to study the effect of dietary pectin, cellulose, hemicellulose, and zinc on human urinary excretion of ascorbic acid. The project consisted of two 33-day controlled feeding studies involving a total of 19 adult men and women normal health. Within each study all subjects received all experimental treatments. In study A during the four 7-day experimental periods the ground peanut based diets were varied as follows: no supplement, 14.2 g of hemicellulose supplement, 14.2 g of cellulose supplement, or 14.2 g of pectin supplement per subject per day. Mean urinary excretion of ascorbic acid by subjects while receiving these supplements were 26.10, 32.27, 26.27, or 20.60 mg/day, respectively. In study B during the four 7-day randomly arranged experimental periods, the following alterations were made to the basal diet: supplement of 14.2 g of pectin plus 1.3 g of zinc, 14.2 g of pectin plus 9.3 g of zinc, 4.2 g pectin plus 1.3 g of zinc, and 4.2 g of pectin plus 9.3 g of zinc. Mean urinary ascorbic acid excretion of subjects while receiving these diets were as follows: 20.61, 23.18, 28.07, 18.99. Hemicellulose supplement enhanced urinary excretion of ascorbic acid while pectin and zinc resulted in decreased urinary excretion of this vitamin. Increased urinary excretion of ascorbic acid at constant intake levels is thought usually to be indicative of enhanced absorption or of decreased need.

Adult↗
PubMed1986

Effects of purified dietary fiber sources on beta-carotene utilization by the chick.

Effects of various purified dietary fiber components on beta-carotene utilization by the chick were investigated in two experiments (expt.). Eight-day-old Columbian X New Hampshire male (expt. 1) or female (expt. 2) chicks were fed a vitamin A-deficient diet for 1 wk and then fed beta-carotene-supplemented diets containing 0% fiber, 7% arenaceous flour or 7% of a purified fiber source for 4 wk. Results of expt. 1 showed that hemicellulose, lignin and citrus pectin, but not arenaceous flour or polygalacturonic acid, depressed beta-carotene utilization by the chick, as measured by percentage of consumed beta-carotene stored in liver as vitamin A relative to the 0% fiber control. In expt. 2, effects of the methoxyl content of pectin were studied. High and medium methoxyl apple pectin, citrus pectin and polygalacturonic acid reduced storage of vitamin A in liver. Low methoxyl apple pectin had no significant effect on beta-carotene utilization. Thus, several purified forms of dietary fiber significantly reduced beta-carotene utilization by chicks when fed at the 7% supplementary level. Moreover, with pectin, there was an inverse relationship between methoxyl content of pectin and beta-carotene utilization.

Animals↗