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1.
The protective effect of proanthocyanidins from persimmon peel, using both oligomers and polymers, was investigated in a db/db type 2 diabetes model. Male db/db mice were divided into three groups: control (vehicle), polymer-, or oligomer- (10 mg/(kg body weight x day x p.o.)) administered mice. Age-matched nondiabetic m/m mice were used as a normal group. The administration of proanthocyanidins reduced hyperglycemia in db/db mice through a decline in the serum level of glucose and glycosylated protein. In addition, it had a strong effect on hyperlipidemia through lowering levels of triglyceride, total cholesterol, and nonesterified fatty acids. The protective effect against hyperglycemia and hyperlipidemia was greater in the groups administered the oligomeric rather than polymeric form. The increased oxidative stress in db/db mice was attenuated by the administration of oligomers through inhibiting the generation of reactive oxygen species and lipid peroxidation and elevating the reduced glutathione/oxidized glutathione ratio. On the other hand, polymers did not show such an effect. Moreover, expressions in the liver of sterol regulatory element binding protein (SREBP)-1 and SREBP-2 were downregulated by the administration of proanthocyanidins, especially the oligomeric form. Oligomers caused a slight elevation in the expression of peroxisome proliferator-activated receptors alpha. Furthermore, oligomeric proanthocyanidin regulated the expression of nuclear factor kappaB in db/db type 2 diabetes via the activation of inhibitor protein kappaB-alpha. It also attenuated the protein expressions of cyclooxygenase-2 and inducible nitric oxide synthase. This suggests that oligomers would act as a regulator in inflammatory reactions associated with oxidative stress in type 2 diabetes. The present study results suggest that proanthocyanidin administration, especially the oligomeric form, may improve oxidative stress via the regulation of hyperlipidemia than hyperglycemia in type 2 diabetes.  相似文献   

2.
Recent evidence strongly suggests that oxidative stress due to redox imbalance is causally associated with inflammatory processes and various diseases including diabetes. We examined the effects of proanthocyanidin from persimmon peel, using both oligomers and polymers, against oxidative stress with elucidation of the underlying mechanisms in streptozotocin-induced diabetic rats. The elevation of lipid peroxidation in the kidney and serum under the diabetic condition was decreased by the administration of proanthocyanidin. The suppression of reactive oxygen species generation and elevation of the reduced glutathione/oxidized glutathione ratio were observed in the groups administered proanthocyanidin. These results support the protective role of proanthocyanidin from oxidative stress induced by diabetes. Moreover, proanthocyanidin, especially its oligomeric form, affected the inflammatory process with regulation of related protein expression, inducible nitric oxide synthase, cyclooxygenase-2, and upstream regulators, nuclear factor kappaB, and inhibitor-binding protein kappaB-alpha. Proanthocyanidin ameliorated the diabetic condition by decreases of serum glucose, glycosylated protein, serum urea nitrogen, urinary protein, and renal advanced glycation endproducts. In particular, oligomeric proanthocyanidin exerted a stronger protective activity than the polymeric form. This suggests that the polymerization of proanthocyanidin has an effect on its protective effect against diabetes. The present study supports the beneficial effect of proanthocyanidin against diabetes and oxidative stress-related inflammatory processes.  相似文献   

3.
Mildly extracted peanut allergen Ara h 1 was previously reported to occur as an oligomeric complex. In this paper we describe how the protein in this oligomeric complex interacts noncovalently with phenolic compounds of the proanthocyanidin type. These interactions are being disrupted during anion exchange chromatography, resulting in the dissociation of the oligomeric Ara h 1 complex into protein trimers. By use of the known three-dimensional structure of beta-conglycinin, a soy protein homologous to Ara h 1, proline-rich regions were observed in silico on both faces of its trimeric structure, which are conserved in Ara h 1. These proline-rich regions could explain the binding of proanthocyanidins to Ara h 1 and the formation of multiple Ara h 1 trimer complexes. This was supported by the observation that the addition of peanut proanthocyanidins to trimeric Ara h 1 and to beta-conglycinin resulted in the formation of soluble oligomeric protein complexes. The structurally related legumin proteins do not contain such proline-rich regions on both sides of the protein, and proanthocyanidins were shown to have a lower affinity for legumin proteins from peanuts and soybeans (peanut allergen Ara h 3 and soy glycinin, respectively). Ara h 1 present as the oligomeric complex is assumed to be the representative form of the allergen in which it is consumed by humans.  相似文献   

4.
European, small-fruited cranberries (Vaccinium microcarpon) and lingonberries (Vaccinium vitis-idaea) were characterized for their phenolic compounds and tested for antioxidant, antimicrobial, antiadhesive, and antiinflammatory effects. The main phenolic compounds in both lingonberries and cranberries were proanthocyanidins comprising 63-71% of the total phenolic content, but anthocyanins, hydroxycinnamic acids, hydroxybenzoic acids, and flavonols were also found. Proanthocyanidins are polymeric phenolic compounds consisting mainly of catechin, epicatechin, gallocatechin, and epigallocatechin units. In the present study, proanthocyanidins were divided into three groups: dimers and trimers, oligomers (mDP 4-10), and polymers (mDP > 10). Catechin, epicatechin, A-type dimers and trimers were found to be the terminal units of isolated proanthocyanidin fractions. Inhibitions of lipid oxidation in liposomes were over 70% and in emulsions over 85%, and in most cases the oligomeric or polymeric fraction was the most effective. Polymeric proanthocyanidin extracts of lingonberries and cranberries were strongly antimicrobial against Staphylococcus aureus, whereas they had no effect on other bacterial strains such as Salmonella enterica sv. Typhimurium, Lactobacillus rhamnosus and Escherichia coli. Polymeric fraction of cranberries and oligomeric fractions of both lingonberries and cranberries showed an inhibitory effect on hemagglutination of E. coli, which expresses the M hemagglutin. Cranberry phenolic extract inhibited LPS-induced NO production in a dose-dependent manner, but it had no major effect on iNOS of COX-2 expression. At a concentration of 100 μg/mL cranberry phenolic extract inhibited LPS-induced IL-6, IL-1β and TNF-α production. Lingonberry phenolics had no significant effect on IL-1β production but inhibited IL-6 and TNF-α production at a concentration of 100 μg/mL similarly to cranberry phenolic extract. In conclusion the phenolics, notably proanthocyanidins (oligomers and polymers), in both lingonberries and cranberries exert multiple bioactivities that may be exploited in food development.  相似文献   

5.
The relationships between variations in grapevine (Vitis vinifera L. cv. Pinot noir) growth and resulting fruit and wine phenolic composition were investigated. The study was conducted in a commercial vineyard consisting of the same clone, rootstock, age, and vineyard management practices. The experimental design involved monitoring soil, vine growth, yield components, and fruit composition (soluble solids, flavan-3-ol monomers, proanthocyanidins, and pigmented polymers) on a georeferenced grid pattern to assess patterns in growth and development. Vine vigor parameters (trunk cross-sectional area, average shoot length, and leaf chlorophyll) were used to delineate zones within both blocks to produce research wines to investigate the vine-fruit-wine continuum. There was no significant influence of vine vigor on the amount of proanthocyanidin per seed and only minimal differences in seed proanthocyanidin composition. However, significant increases were found in skin proanthocyanidin (mg/berry), proportion of (-)-epigallocatechin, average molecular mass of proanthocyanidins, and pigmented polymer content in fruit from zones with a reduction in vine vigor. In the wines produced from low-vigor zones, there was a large increase in the proportion of skin tannin extracted into the wine, whereas little change occurred in seed proanthocyanidin extraction. The level of pigmented polymers and proanthocyanidin molecular mass were higher in wines made from low-vigor fruit compared to wines made from high-vigor fruit, whereas the flavan-3-ol monomer concentration was lower.  相似文献   

6.
The structure of a polymeric proanthocyanidin fraction isolated from pear juice was characterized by NMR, ESI/MS, and MALDI-TOF/MS analyses, and its antioxidant activity was investigated using the DPPH free radical scavenging method. The results obtained from 13C NMR analysis showed the predominance of signals representative of procyanidins. Typical signals in the chemical shift region between 70 and 90 ppm demonstrated the exclusive presence of epicatechin units. The results obtained through negative ESI/MS analysis showed singly and doubly charged ions corresponding to the molecular mass of procyanidins with a degree of polymerization up to 22. The spectra obtained through MALDI-TOF/MS analysis revealed the presence of two series of tannin oligomers. Supporting the observations from NMR spectroscopy, the first series consists of well-resolved tannin identified as procyanidin polymers units with chain lengths of up to 25. A second series of monogalloyl flavan-3-ols polymers with polymerization degree up to 25 were also detected. This is the first mass spectrometric evidence confirming the existence of galloylated procyanidin oligomers in pear fruits. Within each of these oligomers, various signals exist suggesting the presence of several oligomeric tannins. The antioxidant properties of the polymeric fraction were investigated through reduction of the DPPH free radical, and the results obtained showed that the polymeric fraction exhibited a higher antioxidant power compared to those of (+)-catechin and B3 procyanidin dimer.  相似文献   

7.
Changes in proanthocyanidin chain length in winelike model solutions   总被引：2，自引：0，他引：2  
Reactions of seed and skin proanthocyanidins in the presence or absence of (-)-epicatechin were followed in winelike solutions over 53 days at 30 degrees C. Proanthocyanidins were separated from flavanol monomers by sequential elution from a Sep Pak cartridge, and changes in proanthocyanidin composition were monitored by thiolysis analysis of the proanthocyanidin fraction. In solutions containing no free (-)-epicatechin, trace amounts of monomers were released and important losses of proanthocyanidins were measured, but their average composition and mean degree of polymerization (mDP) were hardly modified. In the presence of (-)-epicatechin, the mDP value decreased and oligomeric proanthocyanidins accumulated throughout the incubation while losses of total units were dramatically reduced. Our data indicate that interflavanic bond cleavage of proanthocyanidins occurred under mild acidic conditions such as encountered in wine and that the resulting carbocation proceeded to unknown species. The latter reaction did not take place in the presence of (-)-epicatechin. Epicatechin added to the intermediate carbocation, thus being incorporated as the end unit of a shorter proanthocyanidin chain. The results of this study are discussed in relation to the loss of astringency reported during wine aging.  相似文献   

8.
Six Manitoba fruits were analyzed for their phytochemical content and antioxidant activity in order to increase their production and marketability. The major proanthocyanidins (flavanols) present in whole fruit, juice, and pulp of strawberry, Saskatoon berry, raspberry, wild blueberry, chokecherry, and seabuckthorn were measured. The extraction and purification were facilitated using flash column chromatography, while separation and identification were accomplished by using HPLC and LC-MS techniques. The total proanthocyanidin contents varied from 275.55 to 504.77 mg/100 g in the whole fruit samples. Raspberry contained the highest content, and seabuckthorn showed the lowest content of total flavanols. The highest concentration of proanthocyanidin in juice was found in Saskatoon berry (1363.34 mg/100 mL) and the lowest value in strawberry (622.60 mg/100 mL). HPLC and LC-MS results indicated that epicatechin was the most abundant flavanol followed by B2 in the berry samples, while no catechin or B1 was detected in these fruits. A series of oligomers and polymers were detected in all samples. The recovery percentage was obtained from the ratio of the unspiked samples to the area of spiked samples. Monomers, dimers, oligomers, and polymers gave recovery ranges of 83-99%. The lipophilic and hydrophilic antioxidant capacities of whole fruit, juice, and pulp extracts were measured by the oxygen radical absorbance capacity (ORAC) procedure. In whole fruits, the ORAC values varied from 135 to 479 mg/100 g TE in the MeOH fraction. The corresponding ORAC values varied from 115.30 to 733.15 mg/100 g for the acetone fraction. In juice, all berries showed the same antioxidant capacity (P > 0.05) (133.0-312.0 mg/100 g) in the MeOH fraction, with the exception of raspberry (603.0 mg/100 g). Overall, MeOH fractions mainly contained monomers and dimers with smaller amounts of oligomers and polymers when compared to the acetone fractions. Acetone fractions mainly contained polymers and some oligomers. Although acetone fractions contained a higher quantity of total proanthocyanidins, their antioxidant capacities were lower than MeOH fractions.  相似文献   

9.
Extracts from wild blueberry (Vaccinium angustifolium Ait.) were separated into proanthocyanidin-rich fractions using liquid vacuum and open column chromatography on Toyopearl and Sephadex LH-20, respectively. Fractions were characterized using analytical tools including mass spectrometry and NMR spectroscopy; fraction composition was correlated with bioactivity using antiproliferation and antiadhesion in vitro assays. There was a significant positive correlation between proanthocyanidin content of different fractions and biological activity in both the antiproliferation and antiadhesion assays. Two fractions containing primarily 4-->8-linked oligomeric proanthocyanidins with average degrees of polymerization (DPn) of 3.25 and 5.65 inhibited adhesion of Escherichia coli responsible for urinary tract infections. Only the fraction with a DPn of 5.65 had significant antiproliferation activity against human prostate and mouse liver cancer cell lines. These findings suggest both antiadhesion and antiproliferation activity are associated with high molecular weight proanthocyanidin oligomers found in wild blueberry fruits.  相似文献   

10.
In this study, microscale fermentations were conducted on Vitis vinifera L. cv. Merlot. Five treatments were established varying from 0-100% crushed fruit (25% increments x 5 replicates). Caps were kept submerged throughout the experiment, and fermentation temperatures were maintained at 25 degrees C. Samples were collected throughout fermentation and from the free run and press wine at the time of pressing. Proanthocyanidins were determined by acid-catalyzed depolymerization in the presence of phloroglucinol, followed by reversed phase, high performance liquid chromatography (RP-HPLC). Total proanthocyanidin extraction increased with time in all treatments. In addition, crushing increased the rate at which proanthocyanidins were extracted. When the extraction of skin and seed proanthocyanidins were monitored separately, skin proanthocyanidin extraction rate exceeded that for seed proanthocyanidins and followed a Boltzmann sigmoid extraction model. The highest proanthocyanidin concentration for skin (435 mg/L) and seed (344 mg/L) was observed for the 75% crushed fruit treatment at the time of pressing (17 days). The highest skin proanthocyanidin proportion (79%) was observed for the 75% crushed fruit treatment on day 9 with a total proanthocyanidin concentration of 439 mg/L. For all treatments, skin proanthocyanidin extraction reached a plateau concentration prior to pressing, with the plateau concentration increasing with crushing. Seed proanthocyanidin concentration increased throughout maceration.  相似文献   

11.
Antioxidant capacity, as measured by oxygen radical absorbance capacity (ORAC(PE)), total phenolic, total and individual anthocyanins, and proanthocyanidin fraction contents were evaluated in red and white wines from grapes. A comparison in terms of antioxidant capacity is made with nontraditional wines made from highbush blueberry. Blueberries are among fruits that are best recognized for their potential health benefits. In red wines, total oligomeric proanthocyanidin content, including catechins, was substantially higher (177.18 +/- 96.06 mg/L) than that in white wines (8.75 +/- 4.53 mg/L). A relative high correlation in red wines was found between ORAC(PE) values and malvidin compounds (r = 0.75, P < 0.10), and proanthocyanidins (r = 0.87, P < 0.05). In white wines, a significant correlation was found between the trimeric proanthocyanidin fraction and peroxyl radical scavenging values (r = 0.86, P < 0.10). A moderate drink (1 drink per day, about 140 mL) of red wine, or white wine, or wine made from highbush blueberry corresponds to an intake of 2.04 +/- 0.81 mmol of TE, 0.47 +/- 0.15 mmol of TE, and 2.42 +/- 0.88 mmol of TE of ORAC(PE)/day, respectively.  相似文献   

12.
The monomeric, oligomeric, and polymeric flavan-3-ol composition of wines, grape seeds, and skins from Vitis vinifera L. cv. Graciano, Tempranillo, and Cabernet Sauvignon has been studied using (1) fractionation by polyamide column chromatography followed by HPLC/ESI-MS analysis, (2) fractionation on C(18) Sep-Pak cartridges followed by reaction with vanillin and acid-catalyzed degradation in the presence of toluene-alpha-thiol (thiolysis). The content of monomers ((+)-catechin and (-)-epicatechin), procyanidin dimers (B3, B1, B4, and B2), trimers (T2 and C1), and dimer gallates (B2-3-O-gallate, B2-3'-O-gallate, and B1-3-O-gallate) ranged from 76.93 to 133.18 mg/L in wines, from 2.30 to 8.21 mg/g in grape seeds, and from 0.14 to 0.38 mg/g in grape skins. In wines, the polymeric fraction represented 77-84% of total flavan-3-ols and showed a mean degree of polymerization (mDP) value of 6.3-13.0. In grapes, the polymeric fraction represented 75-81% of total flavan-3-ols in seeds and 94-98% in skins and showed mDP values of 6.4-7.3 in seeds and 33.8-85.7 in skins. All the monomeric flavan-3-ols and oligomeric procyanidins found in wines were also present in seeds, although differences in their relative abundances were seen. The skin polymeric proanthocyanidins participated in the equilibration of the wine polymeric proanthocyanidin fraction, especially contributing to the polymer subunit composition and mDP.  相似文献   

13.
Phenolic compounds in an aqueous infusion of leaves of Ficus deltoidea (Moraceae), a well-known herbal tea in Malaysia, were analyzed by HPLC coupled to photodiode array and fluorescence detectors and an electrospray ionization tandem mass spectrometer. Following chromatography of extracts on a reversed phase C(12) column, 25 flavonoids were characterized and/or tentatively identified with the main constituents being flavan-3-ol monomers, proanthocyanidins, and C-linked flavone glycosides. The proanthocyanidins were dimers and trimers comprising (epi)catechin and (epi)afzelechin units. No higher molecular weight proanthocyanidin polymers were detected. The antioxidant activity of F. deltoidea extract was analyzed using HPLC with online antioxidant detection. This revealed that 85% of the total antioxidant activity of the aqueous F. deltoidea infusion was attributable to the flavan-3-ol monomers and the proanthocyanidins.  相似文献   

14.
We determined the phenolic, anthocyanin, and proanthocyanidin content of three brown, purple, and red rice brans isolated from different rice varieties using HPLC-PDA with the aid of 27 standards of known structure and matching unknown peaks to a spectral library of known compounds. Antioxidative capacities were determined by DPPH and ORAC and cell-inhibiting effects using an MTT assay. Based on the calculated IC(50) values, the light-brown bran had no effect, the purple bran exhibited a minor effect on leukemia and cervical cancer cells, and the red bran exhibited strong inhibitory effects on leukemia, cervical, and stomach cancer cells. High concentrations of protocatechuic acid and anthocyanins in purple bran and proanthocyanidins in red bran were identified. The red bran was further fractionated on a Sephadex column. Fraction 3 rich in proanthocyanidin oligomers and polymers had the greatest activity. Red bran has the potential to serve as a functional food supplement for human consumption.  相似文献   

15.
Survival of rhizobia applied to the surface of legume seeds is poor due to factors such as desiccation. Poor survival of rhizobia results in poor nodulation and yield of legumes. Selecting polymeric adhesives for inoculation of legume seed with rhizobia that provide protection during desiccation may improve survival and increase the potential for maximum legume yields. Vacuum-drying cells after suspension in selected polymers proved an effective method for screening the potential of polymers to improve the desiccation tolerance of rhizobia. The effect of different polymers on survival of desiccated rhizobia could be attributed to their different chemical and physical properties. The specific protective properties of polymers have been difficult to determine due to the variation in the chemical nature of polymers often compared. In this research polyvinyl alcohol (PVA) with varying degrees of hydrolysis provided a useful range of measurable physical properties against which bacterial survival could be measured. PVA with a percent hydrolysis in the range 86.5-89% was better able to protect desiccated cells of a range of rhizobial strains than polymers with higher (98.5%) or lower (78.5-82%) degrees of hydrolysis. The percent hydrolysis affected the moisture properties of PVA and survival of rhizobia was not maximised with high moisture sorption or low water activity by the polymer but rather when moisture properties were at an intermediate level. In comparison, survival was poorest in highly hygroscopic polymers methyl cellulose (MC) and polyvinyl pyrrolidone (PVP). The survival profile of desiccated rhizobia stored at different relative humidities was altered when cells were embedded in different polymers and is probably related to moisture sorption by those polymers. The percent hydrolysis also affects the extent to which PVA is able to stabilise colloids against the precipitating action of KCl. The colloid-stabilising property and survival was highest at 86.5-89% indicating that this property may be manipulated to achieve better survival. There is an indication that highly stabilising PVA may lead to more evenly dispersed cells providing more colony forming units rather than better survival. However, survival was not strongly correlated to the colloid-stabilising properties of the other polymers and was very poor after suspension in highly stabilising MC indicating a strong interaction between factors. Synthetic polymers designed to improve survival of rhizobia exposed to desiccation stress should include properties that combine high stabilisation and optimum moisture sorption properties.  相似文献   

16.
Procyanidins are a class of polyphenols in the plant kingdom. Lotus ( Nelumbo nucifera Gaertn.) seedpods, the inedible part of lotus and a byproduct during the production of lotus seeds, were found to be a new source rich in procyanidins. Detailed information about oligomeric procyanidins in lotus seedpods remains unknown. In this study, lotus seedpods were extracted using 60% aqueous methanol and characterized with phloroglucinolysis and liquid chromatography (mass spectrometry with an electrospray ionization source). The results indicate that the oligomeric and polymeric fraction had a mean degree of polymerization of 3.2 and 15.4, respectively, and consisted of (+)-catechin (m/z 289), gallocatechin or epigallocatechin (m/z 305), quercetin glycoside (m/z 463), quercetin glucuronide (m/z 477), procyanidin dimers (m/z 577.1), proanthocyanidin dimer gallate (m/z 593.3), prodelphinidin dimers (m/z 609.1), procyanidin trimers (m/z 865.1), etc. Quercetin glucuronide was further purified using flash chromatography and identified as quercetin-3-O-β-glucuronide by determining its exact mass using ion-trap time-of-flight mass spectrometry and 1H and 13C nuclear magnetic resonance, 1H-detected heteronuclear single-quantum coherence, and 1H-detected heteronuclear multiple-bond correlation analyses.  相似文献   

17.
Grape antioxidant dietary fiber (GADF) is a phenolic-rich dietary fiber matrix. The aim of this work was to determine which phenolic compounds come into contact with colonic epithelial tissue after the ingestion of GADF. By use of HPLC-ESI-MS/MS techniques phenolic metabolites were detected in feces, cecal content, and colonic tissue from rats. Free (epi)catechin (EC) was detected in all three sources, and more than 20 conjugated metabolites of EC were also detected in feces. Fourteen microbially derived phenolic metabolites were also identified in feces, cecal content, and/or colonic tissue. These results show that during transit along the digestive tract, proanthocyanidin oligomers and polymers are depolymerized into EC units. After ingestion of GADF, free EC and its conjugates, as well as free and conjugated microbially derived phenolic metabolites, come into contact with the intestine epithelium for more than 24 h and may be partly responsible for the positive influence of GADF on gut health.  相似文献   

18.
Proanthocyanidins were isolated from the skins of Cabernet Sauvignon grapes at different stages of grape development in order to study the effect of proanthocyanidin modification on the interaction with grape cell wall material. After veraison, the degree of proanthocyanidin polymerization increased, and thereafter was variable between 24 and 33 subunits as ripening progressed. Affinity of skin cell wall material for proanthocyanidin decreased with proanthocyanidin ripeness following veraison. A significant negative relationship (R2=0.93) was found for average proanthocyanidin molecular mass and the proportion of high molecular mass proanthocyanidin adsorbed by skin cell wall material. This indicated that as proanthocyanidin polymerization increased, the affinity of a component of high molecular mass proanthocyanidins for skin cell wall material declined. This phenomenon was only associated with skin proanthocyanidins from colored grapes, as high molecular mass proanthocyanidins of equivalent subunit composition from colorless mutant Cabernet Sauvignon grapes had a higher affinity for skin cell wall material.  相似文献   

19.
Proanthocyanidin polymers, oligomers, and the structurally related monomer (+)-catechin were labeled by incorporation of radioactive precursors in shoots of willow tree (Salix caprea L.). [1-(14)C]-Acetate and [U-(14)C]-phenylalanine precursors were fed through the cut stems or petioles of leaves. Optimization of several parameters such as the nature and origin of the plant material, leaf maturity, nature, and quantity of radioactive precursor applied and the duration of metabolism led to incorporation yields of 3.2% and to specific activities of 500 microCi/g. Detailed characterization of the products (polymerization degree, procyanidin/prodelphinidin ratio, specific activities) and purification by chromatography are reported. Some sugars bound to radiolabeled proanthocyanidin polymers were removed by enzymic treatment with a mixture of glycosidases. A radioactive purity close to 100% and specific activities suitable for bioavailability studies were obtained.  相似文献   

20.
Commercially available mannoprotein preparations were tested in Tempranillo winemaking to determine their influence on polysaccharide, polyphenolic, and color composition. No effect was found in the content of grape arabinogalactans, homogalacturonans, and type II rhamnogalacturonans. In contrast, mannoprotein-treated samples showed considerably higher values of high-molecular-weight mannoproteins (bMP) than controls from the beginning of alcoholic fermentation, although these differences diminished as vinification progressed. The bMP decrease observed in the mannoprotein-treated samples coincided with a substantial reduction in their proanthocyanidin content and wine stable color, suggesting a precipitation of the coaggregates mannoprotein-tannin and mannoprotein-pigment. Contrary to what is widely described, these results revealed that at the studied conditions, mannoproteins did not act as stabilizing colloids. Mannoprotein addition did not modify the content and composition of either monomeric anthocyanins or other monomeric phenolics, and it did not affect monomeric anthocyanin color.  相似文献   

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