KOH-soluble Fractions Research Articles

Reduced degradation of the cell wall polysaccharides maintains higher tissue integrity of papaya (Carica papaya L.) during chilling storage

Papaya (Carica papaya L.) fruit are vulnerable to chilling injury (CI), and the symptoms of CI develop more intensively when the fruit are stored at 6 ℃ rather than 1 ℃. This is considered to be abnormal CI behavior of papaya fruit, a phenomenon that is unclear but thought to be related to cell wall metabolism. Thus, this study examined the relationship between the development of CI and alterations of the cell wall metabolism in papaya fruit stored at 1 ºC and 6 ℃. The 1 ℃-storage maintained the integrity of the papaya exocarp and alleviated the development of CI and the loss of free moisture. Ultrastructural observations demonstrated that the middle lamellae were denser in papaya fruit stored at 1 ℃ than those in 6 ℃-storage, which alleviated the disintegration of cell wall at 1 ℃-storage. Compared with 6 ℃-storage, 1 ℃-storage inhibited the degradation of Na2CO3-soluble pectin, CDTA-soluble pectin, and cellulose. The 1 ℃-storage also delayed the solubilization of water-soluble pectin and the transformation of 24% KOH-soluble fraction to the 4% KOH-soluble fraction. Lower activities of cell wall-modifying enzymes, including pectin methylesterase, polygalacturonase, pectate lyase, β-galactosidase, xyloglucan endotransglycosylase, and cellulase, were observed in papaya fruit stored at 1 ℃. These results suggest that alleviating the degradation of cell wall polysaccharides maintains higher tissue integrity in papaya fruit during chilling storage.

Sequential extraction, structural characterization, and antioxidant activity of polysaccharides from Dendrocalamus brandisii bamboo shoot shell

Polysaccharides including water-soluble fraction (W), 1,2-Cyclohexanediaminetetraacetic acid (CDTA)-soluble fraction (CA), sodium carbonate (Na2CO3)-soluble fraction (SC), 1 M potassium hydroxide (KOH)-soluble fractions (PH1), and 4 M KOH-soluble fraction (PH4) were successively extracted from Dendrocalamus brandisii bamboo shoot shells using water, CDTA, Na2CO3, and KOH solution. The analytical methods were employed to initially identify the structural characteristics of the five polysaccharide fractions, and their antioxidant capacities in vitro were determined. According to the data, the average molecular weight of the five polysaccharide fractions was between 4 816 and 993 935 Da. In all four types (CA, SC, PH1, and PH4), xylose was the most abundant monosaccharide, especially in PH1 and PH4. Both PH1 and PH4 were found to contain 1,4-β-d-Xylp as their main chain, as determined by nuclear magnetic resonance (NMR) spectroscopy. Additional research into CA and SC's antioxidant potential is required since they both showed potent in vitro antioxidant activities.

Combined high-throughput and fractionation approaches reveal changes of polysaccharides in blueberry skin cell walls during fermentation for wine production

There have been rare reports about the structure/composition of polymers in blueberry skin and their changes during fermentation for wine production. In this study, the compositional changes occurring in blueberry skin during fermentation were tracked by a combination of cell wall analysis techniques including infra-red spectroscopy, monosaccharide analysis, and comprehensive microarray polymer profiling (CoMPP). The cross-corroborating data revealed that blueberry skin cell wall is particularly rich in xyloglucan. Chemical fractionation analysis indicated that the KOH soluble fraction is a dominant fraction in fermented blueberry skin. Interestingly, the KOH soluble fraction contained abundant epitopes associated with pectin branch chains, indicating tight binding of some enzyme-resistant pectin polymers to hemicellulose. This study provides important implications for the development of effective strategies to extract beneficial substances (such as aromatics, tannins and pigments) from berry tissues during processing.

Ethanol vapor delays softening of postharvest blueberry by retarding cell wall degradation during cold storage and shelf life

Blueberry fruit were treated with 500 μL L−1 ethanol for 18 h and then stored at 0 ± 0.5 °C with 90 % relative humidity (RH) for 40 d. The firmness, contents of cell wall polysaccharides, activities of cell wall-degrading enzymes (CWDEs), and cell wall ultrastructure in the blueberry fruit were determined during storage. The results showed that the decline in firmness of blueberries was delayed by ethanol vapor treatment during cold storage and shelf life, compared to the control. The contents of water-soluble pectin (WSP) and 4 % KOH-soluble fraction (4KSF) in ethanol-treated blueberries were reduced compared to those in the control. The contents of EDTA-soluble pectin (ESP), Na2CO3-soluble pectin (SCSP), 24 % KOH-soluble fraction (24KSF), and cellulose in ethanol-treated blueberries were higher than the control. The activities of pectin methylesterase (PME), polygalacturonase (PG), carboxymethyl cellulase (CMCase), β-glucosidase (β-Glu), β-galactosidase (β-Gal), α-galactosidase (α-Gal), and α-mannosidase (α-Man) in blueberries were suppressed by ethanol vapor treatment. However, there was no significant difference in the activity of α-arabinofuranosidase (α-Af) between ethanol-treated blueberries and the control. Moreover, ethanol vapor treatment delayed the destruction of the cell wall structure of the blueberry fruit via ultrastructural observations. Ethanol vapor treatment can retard the disassembly of cell wall polysaccharides by inhibiting CWDEs activities, thereby delaying blueberry softening.

Perennial halophyte Salicornia neei Lag.: Cell wall composition and functional properties of its biopolymers

Salicornia neei halophyte extends in Argentina seashores. To envisage potential applications, cell wall sequential extraction performed on dry plant yielded 1.1, 2.4, 0.3 and 0.9% of pectin fractions respectively extracted by room temperature water, 90 °C-water, CDTA and Na2CO3. They contained 21–33% uronic acids (UA) with low degree of methylation and 0.5–1.2 M ratios of neutral sugars to UA. High arabinose level suggests that long arabinan side-chains maintain cell wall flexibility in water deficit. Fractions also contained 10–36% of proteins. The KOH-soluble fractions (4.3%) were mainly arabinoxylans. At 2.0% w/v, pectin fractions developed “weak gel”-type networks with Ca2+, while arabinoxylans generated “dilute solutions”. Cellulose (28%) and lignin (45.1%) were the main biopolymers in the final residue, which showed low water swelling capacity (3.6 mL/g) due to lignin, increasing when arabinoxylans were also present. Phenolics (9.8%) were mainly water-extractable. Salicornia is a source of biopolymers and antioxidants potentially useful for food applications.

Aqueous ozone treatment inhibited degradation of cellwall polysaccharides in fresh-cut apple during cold storage

The effects of aqueous ozone (AO) treatment on the firmness, cellwall polysaccharide content, enzymatic activity, and gene expression of cell wall-degrading enzymes were investigated in fresh-cut apple during cold storage. AO treatment (1.4 mg L−1 for 5 min) delayed degradation of cellwall polysaccharides to reduce softening of fresh-cut apple. Water-soluble pectin content increased more slowly, while protopectin content, 4% KOH-soluble fraction, and cellulose content decreased at a lower rate in AO-treated fresh-cut apple compared with the control. However, no significant influence was shown on the 24% KOH-soluble fraction. AO treatment promoted increased pectin methylesterase activity, and distinctly inhibited β-galactosidase and α-arabinofuranosidase activities during storage. Polygalacturonase activity was not affected by AO treatment. Meanwhile, AO maintained the intactness of cell walls through repression of Mdβ-Gal and Mdα-Af transcript levels, thereby preserving the textural quality of fresh-cut apple during cold storage.

Characterization of Soluble Glandless Cottonseed Meal Proteins Based on Electrophoresis, Functional Properties, and Microscopic Structure.

This investigation aimed to extract and characterize the GCSM proteins, determine their solubility potential at two different temperatures and different solvents, and explore their functional properties. During the extraction, no water- or ethanol-soluble protein was found. Most of the protein was extracted with KOH solution. GCSM showed major protein bands between 13,273 and 56,564 Da with an isoelectric point of 5.1. The results showed that extraction temperature and solvent affected the amount of protein extracted from GCSM. The highest protein yield (63.4%) was obtained with KOH at 55 °C. Fat content negatively affected the protein solubility. The highest protein purity (99.9%) was obtained with 6% of fat content and the lowest one with 19% of fat content. GCSM has a high glutamic acid content, followed by arginine and aspartic acid compared to the other amino acids. The essential amino acids make up about 30.0% of the total amino acid concentration in KOH-soluble fractions. The results showed a denaturation temperature of GCSM protein ranging from 61.4 to 63.6 °C. Scanning electron microscopy reveals a microglobular protein structure. GCSM protein isolate showed lower (P < 0.05) water-holding and oil-holding capacity but similar gelation properties as soy protein. GCSM protein shows a high foaming capacity at high pH values and high emulsion stability. PRACTICAL APPLICATION: The results of this investigation have a direct impact on the plant protein processing industry. This paper presents a new source of plant protein with a high foaming capacity in alkaline conditions with potential applications for human consumption and feed for aquaculture and animals. The results of this research may impact the cotton producers who can increase their income, and the aquaculture industry will have a cheaper source of protein that can partially substitute the expensive fishmeal. Cottonseed protein can be used to develop high protein extruded snacks and other functional foods, such as plant protein-based food products.

Physicochemical properties and functional bioactivities of different bonding state polysaccharides extracted from tomato fruit

Water-soluble fraction (WSF), CDTA-soluble fraction (CSF), sodium carbonate-soluble fraction (SSF), loosely-bonding KOH-soluble fractions (LKF) and tightly-bonding KOH-soluble fractions (TKF) were sequentially extracted from tomato cell wall polysaccharides. Physicochemical properties and functional bioactivities of these different bonding state tomato fruit polysaccharides (DBTP) were investigated. WSF, CSF and SSF were identified as pectic polysaccharides, while LKF and TKF were identified as hemicellulose. WSF, possessing plenty of galacturonic acids, was considered as an aggregative of linear homogalacturonan with extremely high molecular weight. CSF and SSF, rich in neutral sugars side chains, contained abundant rhamnogalacturonan regions. These polysaccharides exhibited distinct surface morphology and special FTIR spectrums. Thermal analysis manifested that LKF and TKF exhibited higher thermal stability. WSF and SSF showed higher apparent viscosity and elasticity. Assays for functional bioactivities suggested that CSF and SSF displayed stronger antioxidant activities, while CSF, SSF and TKF exhibited higher hypolipidemic activities.

Effects of graft copolymer of chitosan and salicylic acid on reducing rot of postharvest fruit and retarding cell wall degradation in grapefruit during storage

This study was to evaluate the effect of graft copolymer (CTS-g-SA) of chitosan (CTS) and salicylic acid (SA) on the storability of grapefruit fruits during postharvest storage. Results indicate that the graft copolymer treatment significantly depressed green mold caused by Penicillium digitatum. The graft copolymer application kept fruit firmness without impairing the fruit quality. Moreover, the graft copolymer treatment inhibited the activity and gene expression of cell wall-modifying enzymes such as polygalacturonase, cellulase, pectin methylesterase, α-l-arabinofuranosidase, β-galactosidase, and suppressed the modification of cell wall components including covalently bound polysaccharide (sodium carbonate soluble pectin, 24% KOH-soluble fraction), which were associated with fruit softening. These results suggested that graft copolymer application can be recognized as a postharvest technique to suppress rotting and delay softening through inhibiting solubilization of cell wall polysaccharides.

γ-Irradiation treatment decreased degradation of cell-wall polysaccharides in blueberry fruit during cold storage

The influence of irradiation treatment on the relevant indices of blueberry (Vaccinium spp.) softening during cold storage was studied by irradiating Bluecrop blueberries with 60Co source at a dose of 2.5kGy. The effect of irradiation treatment on the firmness and ultrastructure of the cell walls of blueberries and the variations of the content and molecular weight of cell wall polysaccharides were investigated. γ-Irradiation postponed and delayed softening of fruit during cold storage. After 35d of storage, the irradiated blueberry fruit 1.08kg/cm2 firmer than that of control group. In addition, cells were more intact and were more tightly arranged. The content of water-soluble pectin (WSP) increased more slowly, while the contents of EDTA (ethylene diamine tetraacetic acid)-soluble pectin (ESP) and 24% KOH-soluble fraction (24KSF) decreased at a lower rate in irradiated fruit compared with untreated fruit. The content of the total cell wall materials (CWMs) remained unchanged. High-molecular weight polymers in the fruit were less likely to be degraded. However, no significant influences were shown on the sodium carbonate-soluble polysaccharide (SCSP) and 4% KOH-soluble fractions (4KSF). Therefore, γ-irradiation maintained the intactness of cell walls through regulating the solubility and adhesion of polysaccharides in cell walls of the fruit, thereby reducing softening of blueberry fruit during cold storage.

Cell wall metabolism and chilling injury during postharvest cold storage in zucchini fruit

Postharvest cold storage in zucchini fruit extends the commercial life but causes the appearance of chilling injury (CI), characterized by the development of pits and damaged areas at the surface of the fruit. This physiological disorder has been related to alterations of the cell wall metabolism in several fruit. We have analyzed the relationship between the development of CI and the changes that take place at the cell wall due to cold storage in zucchini fruit, as well as the effect of a preconditioning treatment on these changes. Microscopical observations have shown that the surface depressions detected in chilling injured fruit were caused by cell death and cell collapse. Low temperature induced the solubilization of the more soluble pectins, as evidenced by the highest levels of neutral sugars and uronic acids found in control fruit after the cold storage in water-soluble fraction (WSF) and CDTA-soluble fraction (CSF). The results obtained in Na2CO3-soluble fraction (NSF) for both parameters was opposite; higher levels were detected in preconditioned fruit and lower in more damaged fruit. The same behaviour was found in the base soluble hemicelluloses, 1M KOH- and 4M KOH-soluble fractions (1KSF and 4KSF), and in the insoluble cellulose content. Zucchini fruit stored at low temperature showed an increase of the enzymatic activities pectin methylesterase (PME), polygalacturonase (PG), and cellulase (CEL), and an accumulation of mRNA corresponding to a expansin (EXP) gene. Preconditioned fruit showed the lowest levels of these enzymatic activities. Microscopic analysis of CI fruit correlated with the biochemical changes observed in cell wall. Lignin content was higher in control than preconditioned fruit, suggesting a possible role of the lignification process in CI development in zucchini.

Post-storage cell wall metabolism in two sweet cherry (Prunus avium L.) cultivars displaying different postharvest performance.

The biochemical processes underlying firmness loss of sweet cherry (Prunus avium L.) fruit are poorly understood. Studies on cell wall metabolism of sweet cherry have been generally undertaken during on-tree development or at harvest maturity, while published reports on postharvest changes are scarce and fragmentary. In this work, cell wall modifications after storage at 0 ℃ were studied in two cherry cultivars ('Celeste' and 'Somerset') displaying different postharvest potential. Firmness was largely determined by the yields of the Na2CO3- and KOH-soluble fractions, enriched in covalently-bound pectins and in matrix glycans, respectively, and correlated well with ascorbic acid contents. The yields of these two cell wall fractions were correlated inversely with pectinmethylesterase and endo-1,4-β-d-glucanase activities, indicating a relevant role of these two enzymes in postharvest firmness changes in sweet cherry. The amount of solubilised cell wall materials was closely associated to the contents of dehydroascorbic acid, suggesting the possible involvement of oxidative mechanisms in cell wall disassembly. These data may help understanding the evolution of fruit quality during the marketing period, and give hints for the design of suitable management strategies to preserve key attributes.

Effects of freezing and thawing on texture, microstructure and cell wall composition changes in papaya tissues

During storage, frozen fruit may be thawed and refrozen many times before consumption, which may be extremely damaging to the texture of the frozen fruit and reverse the advantage of fast freezing. The effects of freezing and thawing on texture, microstructure and cell wall composition changes in papaya tissues were investigated. The frozen-thawed papayas had an increase in drip loss and a decrease in firmness with increasing number of freeze-thaw cycles. Light microscopy showed irregular shapes and cell damage in parenchyma cells of frozen-thawed papayas, whereas transmission electron microscopy showed loss of cell wall materials in middle lamella. Moreover, destruction of cell wall was observed after being subjected to five freeze-thaw cycles. These changes related with a significant decrease in alcohol-insoluble solids, Na₂CO₃- and 24% KOH-soluble fractions and an increase in the water-, EDTA- and 4% KOH-soluble fractions. This was due to a decrease in the molecular mass of pectic and hemicellulosic polymers in frozen-thawed papayas using high-performance size-exclusion chromatography. The freezing and thawing processes caused fine structural damage and cell wall composition changes which contributed to a loss of drip volume and firmness of papaya tissues.

Effects of cold storage and 1-methylcyclopropene treatments on ripening and cell wall degrading in rabbiteye blueberry (Vaccinium ashei) fruit

The effect of postharvest 1-methylcyclopropene and/or cold storage application on texture quality parameters during storage was determined. The changes in fruit quality (including weight loss, firmness, total soluble solids content, and ethylene production), cell wall material (including water-soluble fraction, ethylenediaminetetraacetic acid-soluble fraction, Na2CO3-soluble fraction, 4% KOH-soluble fraction, and 14% KOH-soluble fraction), and cell wall hydrolase activities (including polygalacturonase, endo-1,4-beta-D-glucanase, pectinesterase, alpha-L-arabinofuranosidase, and beta-galactosidase) were periodically measured up to 25 days after postharvest treatments. The application of cold storage reduced weight loss, ethylene production, and delayed ripening of blueberry fruit. The inhibition of senescence was associated with suppressed increase in cell wall hydrolase activities and retarded solubilization of pectins and hemicelluloses. Furthermore, no obvious differences in firmness, weight loss, ethylene production, and cell wall hydrolase activities between fruits with or without 1-methylcyclopropene application were observed, while significant lower levels of the detected parameters were found in cold storage fruit compared with fruit stored in room temperature. Thus, cold storage can be viewed as an effective means to extend the shelf life of blueberry fruit.

Cell wall modifications and ethylene-induced tolerance to non-chilling peel pitting in citrus fruit

Non-chilling peel pitting (NCPP), a storage disorder resulting in the formation of depressed areas in the peel of many citrus cultivars, is reduced by ethylene treatments. We hypothesized that this effect may be associated with biochemical changes of cell wall components. Therefore, we extracted cell wall material from albedo and flavedo tissues of ‘Navelate’ oranges stored in air, conditioned with ethylene (2μLL−1) for 4 days and subsequently transferred to air, or continuously stored in an ethylene-enriched atmosphere (2μLL−1). Uronic acids and neutral sugars were extracted into five fractions enriched in specific wall polymers namely water-, CDTA-, Na2CO3-, and 1 and 4M KOH-soluble fractions. Pectin insolubilization was found in control fruit at long storage times. Ethylene treatments, alleviating NCPP, increased polyuronide solubility in the albedo and had a slight effect on the flavedo. Ethylene-treated fruit showed greater content of water-soluble neutral sugars and a larger proportion of hemicelluloses readily extractable with 1M KOH, with a concomitant reduction in the 4M KOH-soluble fraction. This suggests that the protective role of ethylene on NCPP is associated with an increased solubilization of the wall of albedo cells.

Fibres from flax overproducing β-1,3-glucanase show increased accumulation of pectin and phenolics and thus higher antioxidant capacity.

BackgroundRecently, in order to improve the resistance of flax plants to pathogen infection, transgenic flax that overproduces β-1,3-glucanase was created. β-1,3-glucanase is a PR protein that hydrolyses the β-glucans, which are a major component of the cell wall in many groups of fungi. For this study, we used fourth-generation field-cultivated plants of the Fusarium -resistant transgenic line B14 to evaluate how overexpression of the β-1,3-glucanase gene influences the quantity, quality and composition of flax fibres, which are the main product obtained from flax straw.ResultsOverproduction of β-1,3-glucanase did not affect the quantity of the fibre obtained from the flax straw and did not significantly alter the essential mechanical characteristics of the retted fibres. However, changes in the contents of the major components of the cell wall (cellulose, hemicellulose, pectin and lignin) were revealed. Overexpression of the β-1,3-glucanase gene resulted in higher cellulose, hemicellulose and pectin contents and a lower lignin content in the fibres. Increases in the uronic acid content in particular fractions (with the exception of the 1 M KOH-soluble fraction of hemicelluloses) and changes in the sugar composition of the cell wall were detected in the fibres of the transgenic flax when compared to the contents for the control plants. The callose content was lower in the fibres of the transgenic flax. Additionally, the analysis of phenolic compound contents in five fractions of the cell wall revealed important changes, which were reflected in the antioxidant potential of these fractions.ConclusionOverexpression of the β-1,3-glucanase gene has a significant influence on the biochemical composition of flax fibres. The constitutive overproduction of β-1,3-glucanase causes a decrease in the callose content, and the resulting excess glucose serves as a substrate for the production of other polysaccharides. The monosaccharide excess redirects the phenolic compounds to bind with polysaccharides instead of to partake in lignin synthesis. The mechanical properties of the transgenic fibres are strengthened by their improved biochemical composition, and the increased antioxidant potential of the fibres supports the potential use of transgenic flax fibres for biomedical applications.

Soluble Polysaccharides Isolation and Characterization from Rabbiteye Blueberry (Vaccinium ashei) Fruits

Five soluble polysaccharide fractions were sequentially extracted with water, EDTA, Na2CO3, 4% KOH, and 14% KOH solutions at room temperature for 4 h from cell wall material of rabbiteye blueberry (Vaccinium ashei) fruits, and their physicochemical properties were examined. The sequential treatments yielded a total 36.02% soluble polysaccharides of the dry cell wall material. HPAEC and spectroscopy (FT-IR, NMR) analyses indicated that water-, EDTA-, and Na2CO3-soluble polysaccharide fractions were mainly composed of pectins, followed by lower amounts of arabinogalactans and glucans, while the two KOH-soluble fractions were mainly composed of hemicelluloses. Homogalacturonan was proven to be the predominant component in the isolated blueberry fruit pectic substance. The isolated blueberry fruit hemicelluloses could be defined as a linear β-(1→4)-linked-xylopyranosyl, in which xylose was the predominant neutral sugar (69.98 to 77.16%), followed by lower amounts of galactose, glucose, arabinose, and mannose.

Structural Characterization of Hemicellulosic Polysaccharides Isolated from Bamboo (Phyllostachys pubescens Mazel)

In the present work water soluble hemicellulosic polysaccharides HPW, 2% NaOH soluble hemicelluloses HPl and HPlll, and 5% KOH soluble fractions HPll and HPlV, were classically separated from bamboo (Phyllostachys pubescens Mazel) aged one year. In addition to sugar composition analysis, the hemicelluloses were also elucidated by GPC, FTIR, NMR and AFM techniques. Xylose (33.70-74.09%) and arabinose (25.03-59.04%) were the main neutral sugar, with ratios of arabinose to xylose being between 0.34 and 1.70. GPC measurement showed that the fractions HPW, HPlll and HPlV precipitated in ethanol presented much broader molecular weight distribution. FTIR and NMR analysis suggested that the bamboo hemicelluloses could be mainly defined as arabinoxylans substituted by (1→2)-linked 4-O-methyl-α-D-glucuronic aid and acetyl group as side chains. AFM images of HPlll revealed a distribution of both island and rod aggregations when 0.01 mg/mL sample in 0.1 M NH4Ac solution was deposited onto freshly cleared mica and air dried.

Multifunctional antioxidant activity of polysaccharide fractions from the soybean byproduct okara

An alcohol insoluble residue (AIR) from okara, a byproduct from soymilk, was mainly composed by indigestible carbohydrate (55.7%). After sequential extraction, three alkali-soluble fractions (12.7% yield) and an insoluble residue (RES, 58.7% yield) were obtained. Soluble polysaccharide fractions showed in vitro reduction power (11–26 μmol Trolox Equivalent (TE)/g dry weight (dw)) and free radical scavenging activity (63–78 μmol TE/g dw). The highest antioxidant activity was exhibited by 0.05 M NaOH-soluble fraction, rich in pectins. The 1 M KOH-soluble fraction had a mixture of hemicellulosic and pectic polysaccharides, and 4 M KOH-soluble fraction contained the bulk of xyloglucans, although some pectins could also be present. RES contained cellulose along with residual pectins. FT-IR spectra of okara and AIR exhibited an absorption band at 1740 cm −1 of carboxylic ester from pectins, which lacked in the fractions. Moreover, they showed absorption bands at 1650 and 1550 cm −1 of proteins, and at 900–890 cm −1 of β-glycosidic linkages. Potential antioxidant activity of okara cell-wall polysaccharides could be attributed to pectins, although the contribution of residual proteins cannot be ruled out.

Cell wall metabolism during durian fruit dehiscence

Changes in cell wall composition and enzyme activities were studied during durian fruit dehiscence. Water-soluble pectin concentrations remained constant for 2 days in both the husk and the dehiscence zone (DZ), and then increased in the DZ toward the end of storage. Chelator-soluble pectin was higher in the DZ at harvest and throughout storage. This pectin fraction increased steadily in both tissues. Na 2CO 3-soluble pectin content was about the same in the husk and the DZ, but slightly decreased during the dehiscence process. Hemicellulose (1 and 4 M KOH-soluble fractions) slowly decreased in the husk and the DZ during storage. The molecular size distribution of the three pectin fractions shifted from a larger molecular size to a smaller size, during durian dehiscence. The DZ was found to contain smaller pectin molecules than the husk. There was no change in molecular size in the 1 M KOH fraction and only a minor change toward the smaller molecular size in the 4 M KOH fraction during the later period of durian dehiscence. Pectin methyl esterase activity, both in the husk and in the DZ, was the same at the beginning of storage. However, differences were observed by the time storage had ended. Polygalacturonase activity slowly increased in both tissues during 8 days of storage, with the activity always being higher in the DZ than in the husk, especially at late dehiscence. β-1,4-Endoglucanase activity increased more in the DZ than in the husk during the dehiscence process. β-Galactosidase activity increased during the first half of fruit ripening, and then declined. The results suggested that the durian dehiscence process mainly involved degradation of chelator-soluble pectin by polygalacturonase.