Pectinesterase Activity Research Articles

Effect of Ultrahigh-Temperature Continuous Ohmic Heating Treatment on Fresh Orange Juice

The scope of this study is the effect of ohmic heating thermal treatment on liquid fruit juice made of oranges. Effects of ohmic heating on the quality of orange juice were examined and compared to those of heat pasteurization at 90 degrees C for 50 s. Orange juice was treated at temperatures of 90, 120, and 150 degrees C for 1.13, 0.85, and 0.68 s in an ohmic heating system. Microbial counts showed complete inactivation of bacteria, yeast, and mold during ohmic and conventional treatments. The ohmic heating treatment reduced pectin esterase activity by 98%. The reduction in vitamin C was 15%. Ohmic-heated orange juice maintained higher amounts of the five representative flavor compounds than did heat-pasteurized juice. Sensory evaluation tests showed no difference between fresh and ohmic-heated orange juice. Thus, high-temperature ohmic-heating treatment can be effectively used to pasteurize fresh orange juice with minimal sensory deterioration.

Effects of low temperature soaking on color and texture of green eggplants

The activities of polyphenol oxidase (PPO) and pectin esterase (PE) in green eggplants during soaking treatments were analyzed to maintain the green color and improve the texture. The optimum temperature of PE was 65 °C, but there was no significant difference from 50 °C to 65 °C, and PE activity could be enhanced by NaCl concentration (0.15–0.25 M); the optimum pH of PPO was at 7.5, but inactivated when the pH was higher than 9.0; Enzymatic browning catalyzed by PPO could occurred when soaking temperature was higher than 55 °C. The trials showed that response surface analysis (RSA) was a suitable method to optimize the soaking conditions. The soaking temperature and soaking time significantly influenced the texture of the green eggplant. Optimum texture (shear force value) was predicted and proved at the conditions of soaking temperature was 52.6 °C, soaking time was 18.9 min and the NaCl concentration was 0.224 M.

Reduction of pectinesterase activity in a commercial enzyme preparation by pulsed electric fields: comparison of inactivation kinetic models

AbstractThe inactivation of pectinesterase (PE) in a commercial enzyme preparation (CEP) under high intensity pulsed electric fields (HIPEF) was studied. After desalting and water dilution of the raw CEP, samples were exposed to exponentially decay waveform pulses for up to 463 µs at electric field intensities ranging from 19 to 38 kV cm−1. Pulses were applied in monopolar mode. Experimental data were fitted to a first‐order kinetic model as well as to models based on Fermi, Hülsheger or Weibull equations to describe PE inactivation kinetics. Characteristic parameters for each model were calculated. Relationships between some of the parameters and process variables were obtained. The Weibull model yielded the best accuracy factor. The relationship between residual PE and input of electrical energy density was found to be that of exponential decay. Copyright © 2005 Society of Chemical Industry

Effects of thermal treatments on pectinesterase activity determined in blood oranges juices

The citrus processing industry aims to maintain turbidity and attractive colour of the juice obtained from Sicilian blood oranges. Nevertheless, the presence of pectinesterase (PE, E.C. 3.1.1.11) causes the loss of these peculiar characteristics, due to precipitation of colloids and very fine pieces of pulp in suspension, with negative effects on colour and clarification of the juices. This study compares total PE activity of Sicilian blood oranges ( Sanguinello, Moro, Tarocco) with the blonde cultivar Navel, checking enzyme stability with various pasteurisation times and temperatures conditions. Decimal reduction time and temperature ( D and z) as well as the kinetic constant ( k) were established to optimise and increase the shelf-life of the pasteurised juice. Finally, a heat treatment (85 °C × 3 min) of both microbiological and enzymatic efficacy has been developed that does not compromise anthocyanin stability; this treatment could be used by the citrus fruit processing industry as a valid alternative in the production of blood orange juices.

Blanching effects on chemistry, quality and structure of green beans (cv. Moncayo)

Green beans (cv. Moncayo) were blanched at 65, 70, 75, 80, 85, 90 and 97 °C for 2.5, 5, 10, 20 and 40 min. Pectinesterase (PE) activity was highest in cell-wall-bound extracts of beans blanched at 70 °C/10 min. The lowest water-soluble pectin fraction, the highest EDTA-soluble pectin fraction and the lowest degree of esterification of the EDTA-soluble fraction were all recorded for the same temperature/time combination; these effects can therefore be attributed to PE activity. Chemical changes did not affect initial firmness of the beans, which was practically constant after blanching at 65, 70, 75 and 80 °C. Simple first-order models were adequate to establish softening kinetics for beans blanched at 85, 90 and 97 °C. In this temperature range, Kramer maximum force was the mechanical parameter that best characterised bean softening by blanching. For all temperatures, short-time blanching increased the coloration and total chlorophyll content of the samples with respect to fresh control, thus precluding the use of simple models. In the treated beans, the ascorbic acid content was consistently lower than in the control and decreased continuously with increasing time. Microphotographs showed no appreciable differences in morphology between fresh and blanched beans at 65, 70 and 75 °C, which would explain the similarity of mechanical behaviour in these samples. Blanching at 85, 90 and 97 °C caused loosening and swelling of the cell walls owing to breakdown of the pectic material, which again helps to explain the observed loss of firmness.

Efficiency of high pressure treatment on inactivation of pathogenic microorganisms and enzymes in apple, orange, apricot and sour cherry juices

The purpose of this study was to investigate the effect of high hydrostatic pressure with a mild heat treatment on Staphylococcus aureus 485, Escherichia coli O157:H7 933 and Salmonella Enteritidis FDA in apple, orange, apricot and sour cherry juices. The effectiveness of the treatment on polyphenol oxidase activity in apple juice and pectinesterase activity in orange juice were also determined. An inoculum of microorganisms was completely inactivated at 350 MPa and 40 °C in 5 min. The residual polyphenol oxidase activity in apple juice after treatment at 450 MPa and 50 °C for 60 min was obtained as 9 ± 2.2%. The residual pectinesterase activity in orange juice after treatment at 450 MPa and 50 °C for 30 min was determined as approximately 7 ± 1.6%. It compares with 12 ± 0.2% at a treatment of 40 °C and 450 MPa for 60 min. Pressure resistant isoenzymes were thought to be responsible for the final residual activity. The inactivation is irreversible and the enzyme is not reactivated upon storage. High pressure processing constitutes an effective technology to inactivate the enzymes in fruit juices. Pressures higher than 400 MPa can be combined with mild heat (<50 °C) to accelerate enzyme inactivation.

Extraction and assay of pectic enzymes from Peruvian carrot ( Arracacia xanthorriza Bancroft.)

Enzyme extraction processes were studied to evaluate the actual activity of pectinesterase (PE) and polygalacturonase (PG) from Peruvian carrot roots. Response surface methodology (RSM) was used to study the effect of NaCl concentration (from 0.5 to 1.5 M), the pH of the homogenate (from 4.0 to 8.0) and the extraction time (from 4 to 52 h) on enzyme activity of the crude extract. The results showed that best conditions for extracting pectic enzymes were 1.0 M NaCl, for 4 h, for both enzymes, whereas pH 7.5 and 4.0 were the appropriate parameters for extracting PE and PG, respectively.

THE STUDY OF THE PROBLEM OF MANGO (MANGIFERA INDICA L.) INTERNAL BREAKDOWN

Analytical studies were carried out in affected and non-affected fruits from cultivars with different sensitivities to the disorder. A histological study was carried out on the peduncle and on the mesocarp of fruits with different degrees of maturity. Internal breakdown of the mesocarp was not due to damage to the vascular elements of the peduncle but due to damage to cells and xylem elements in the mesocarp. A physical, physico-chemical, chemical and biochemical characterization of the fruit showed a reduction in firmness, total soluble solids, total pectins and pectinesterase activity in affected mesocarp tissue. A soilless system trial showed highly affected fruits with higher mesocarp N content and lower mesocarp Ca content than in slightly affected fruits, which showed lower mesocarp N content and higher mesocarp Ca content.

Effect of Liquefaction Enzymes on Methanol Concentration of Distilled Fruit Spirits

Liquefaction enzymes are often used during fermentation of fruit mashes to improve the yield of ethanol and the ability to pump the mash. The liquefaction enzymes hydrolyze pectin, but in addition to the desired pectin hydrolysis activity, the enzymes also have pectinesterase activity which hydrolyzes the methyl ester in pectin resulting in methanol formation. Fermentations of various apple varieties and Bartlett pears were conducted using liquefaction enzymes. The resulting distilled products contained concentrations of methanol above the legal limit of 280 mg/100 mL of 40% ethanol, with the observed methanol concentrations in a range between 320 and 656 mg/100 mL of 40% ethanol. In contrast to the undesired increase in methanol concentration, the enzymes provide only a marginal increase in ethanol yield. The results indicate that liquefaction enzymes should be used with caution for pomace fruit and that methanol monitoring should be implemented if these enzymes are used for commercial products.

Purification and characterisation of carrot (Daucus carota L) pectinesterase

AbstractA pectinesterase isoform with an alkaline isoelectric point of over 8.66 was detected in crude extracts of carrot. The enzyme was purified by ion exchange and molecular exclusion chromatography. The molecular weight of the isoform was 25 kDa, determined in native conditions by filtration through Sephadex G‐75 SF. The enzyme showed a high affinity for its substrate, with Km and Vmax values of 0.031 mg ml−1 and 6.77 units respectively for apple pectin. The pectinesterase activity exhibited an optimum around pH 7.4 and was activated by metallic ions, with optimum activities at NaCl concentrations between 130 and 330 mM and at CaCl2 concentrations between 15 and 50 mM. The enzyme was activated most by Ca2+ and exhibited a greater tolerance of high concentrations of Na+. Comparison of its heat stability with other pectinesterases of vegetable origin indicated that the purified isoform was very thermolabile, being rendered inactive by heating for 5 min at 70 °C. The enzyme was inhibited by high concentrations of polygalacturonic acid and competitively inhibited by D‐galacturonic acid, with a Ki value of 1 mM. Copyright © 2003 Society of Chemical Industry

Pectinesterase activity and the texture of Jalape�o pepper

Jalapeno pepper (Capsicum annuum), a vegetable used in many Mexican dishes, is usually blanched at 90°C for 1–5 min to inactivate enzymes that degrade its quality when it is subsequently canned in vinegar. But this process affects its texture which is undesirable. Food technologists have experienced great difficulty in processing foods so that they closely simulate native foods. The turgor that provides much of the crispness of fresh fruit and vegetables arises from the physiological activity of the living tissue. Pectinesterase (PE) is an enzyme in vegetable tissue that demethyloxylates pectins. This reaction allows interaction of carboxylic groups with calcium ions in the tissue, producing calcium pectates, which impart a firmer texture to the tissue. The main objective of this work was to improve the textural attributes of Jalapeno pepper by means of in situ thermal activation of PE. The temperatures tested were 60 and 65°C over 20, 40, and 60 min. PE activity (Kertesz method), texture (puncture with flat-end punch), and color (parameters L, a, b) were determined. The results indicated that maximum PE activity was achieved when the pepper was immersed in distilled water at 60°C for 40 and 60 min (27.9 and 29.5 U/mL, respectively). The highest resistance force to the puncture test was obtained in the sample treated at 60°C for 40 min (1.83±0.3 kg-f, approximately 6% more than untreated pepper). Pepper treated in this manner also showed the least variation in color (L, +2.64; a, −0.61; b, +3.07) with respect to the untreated control (L, +0.52, a, −0.16, b, +0.61). These results indicate that thermal activation of Jalapeno pepper at 60°C for 40 min enhances the PE activity and thus the firmness of the vegetal tissue, and preserves its original color better than the other pre-treatments.

Study of pectin esterase and changes in pectin methylation during normal and abnormal peach ripening

Peach fruit (Prunus persica cv. Hermosa) were allowed to ripen immediately after harvest or after 30 days of 0°C storage. The fruits lost 75–80% of their firmness after 5 days at 20°C. During ripening after harvest there was a loss of both uronic acid and methyl groups from the cell wall. Cell wall labelling with JIM 7, a monoclonal antibody which recognized pectins with a high degree of methylation, was lower in ripe fruits than in freshly harvested fruits. However, ripe fruit cell walls did not cross‐react with JIM 5, which recognizes pectins with low methylation. During storage, de‐methylation occurred and in fruit ripened after storage there was little further change in pectin methylation or pectin content in the cell walls. The labelling of stored or stored plus ripened cell walls with JIM 7 was similar, but the cell walls of fruit ripened after storage showed some low cross‐reactivity with JIM 5. The in vitro activity and mRNA abundance of pectin esterase (EC 3.1.1.11) was not correlated with the amount of de‐esterification as measured chemically or by immuno‐labelling in the cell walls. Eighty percent of the fruits which ripened after storage developed a woolly texture. It is suggested that woolliness is due to de‐esterification of pectins, not accompanied by depolymerization, which leads to the formation of a gel‐like structure in the cell wall.

Changes in molecular weight of transacylated pectin catalyzed by tomato and citrus pectinesterases as determined by gel permeation chromatography.

The changes in molecular masses of pectin in 0.5% pectin-pectinesterase (PE) mixtures (2 units/mL) incubated at various temperatures, pH values, and NaCl levels for 30 min were observed by a Toyopearl TSK HW-65 (F) gel permeation chromatography. The molecular mass of pectin was remarkably increased from 103 to 266 kDa when the incubation temperature of pectin-tomato PE was increased from 25 to 45 degrees C. A further increase in molecular mass was observed when a pectin-citrus PE mixture was incubated at 65 degrees C. The values of pH and NaCl levels were also crucial to the transacylation activity of PEs. Reaction at pH 7.5 with tomato PE and citrus PE remarkably expanded the molecular mass of pectin to 410 and 670 kDa, respectively. The NaCl level of 0.3-0.5 and 0.3 M was favorable for the transacylation reaction of tomato PE and citrus PE, respectively. Only high methoxylpectin was the suitable substrate for PE to conduct the transacylation reaction.

Changes in pectic enzymes and cellulase activity during guava fruit ripening

Changes in activities of the cell wall degrading enzymes, pectinesterase (PE), polygalacturonase (PG) and cellulase, were studied during the ripening of white- and pink-fleshed guava fruit types. PE activity increased in both guava types up to the climacteric peak of respiration (flesh firmness of 1.21 kg/cm 2) and subsequently decreased. Activities of PG and cellulase increased progressively during the ripening of both guava fruit types with a high correlation between the increase in the activity of the two enzymes and the loss of fruit flesh firmness.

Inhibition of Aspergillus rot by sorbitol in apple fruit with watercore symptoms

Aspergillus rot on apple fruit induced by inoculation with a spore suspension of Aspergillus niger was investigated in relation to watercore severity. The brown areas of Aspergillus rot in the fruit with watercore symptoms were less severe than in fruit without watercore, and the brown areas in the infected flesh were remarkably soft. The softening of flesh tissue with watercore by enzymes produced by A. niger was retarded compared with that in tissue without watercore. Flesh tissue with watercore had higher sorbitol concentrations than tissue without watercore. Sorbitol retarded the softening of flesh tissue by the enzymes produced by A. niger, and galactosidase and pectinesterase (PE) activities were retarded by sorbitol. We conclude that elevated sorbitol concentrations in tissue with watercore might inhibit A. niger infection.

Pectinesterase and Polygalacturonase Activities and Textural Properties of Rubbery Papaya (Carica papaya Linn.)

ABSTRACT:Comparisons in color of flesh, pectin composition, pectinesterase (PE), polygalacturonase, cellulase activities, and textural properties of normal green papaya (NGP), rubbery papaya (RP), and normal yellow and ripe papaya (NYRP) were conducted. RP contained about 9.7% pectin with a degree of esterification of 53.1%, while NYRP contained about only 1.2% pectin with a degree of esterification of about 23.4%. PE activity (13.6 unit/g fresh weight) than in RP was significantly lower (18.0 unit/g fresh weight) in NYRP (P &lt; 0.05), whereas polygalacturonase activity (46.9 unit/g fresh weight) in RP was higher (27.0 unit/g FW) than in NYRP. Therefore, in combination with the fact that water extract from RP displayed an inhibitory ratio of 36.0% on papaya PE activity, we suggest the presence of certain substances with strong PE inhibitory activity in RP.

QUALITY CHANGES OF SOME APPLE CULTIVARS STORED IN NORMAL ATMOSPHERE FOR LONG PERIODS

The research was conducted with apple (Malus communis L.) cultivars Granny Smith, Elstar and Jonagold between 1999-2001. Fruits were stored at 0 plus or minus 5°C and 90-95% relative humidity under normal atmosphere. During the storage period and at the end of shelf life, physical and chemical analysis as weight loss, respiration rate, titratable acidity, pH, water soluble solids, fruit flesh firmness, pectin esterase activity, and fruit skin colour were determined. The optimum storage period for each apple cultivar was determined.

Influence of Pectinesterase Inhibitor from Jelly Fig (Ficus awkeotsang Makino) Achenes on Pectinesterases and Cloud Loss of Fruit Juices

ABSTRACT: Citrus and jelly fig achene pectinesterase (PE) (1 U/mL) activity was remarkably inhibited by PE inhibitor (PEI) (2 mg/mL) from jelly fig (Ficus awkeotsang Makino) achenes, in the absence or presence of 0‐ to 500‐mM salts or 0 to 30% of sugars. Changes in temperature (20 to 40 °C) apparently decreased the activity of citrus PE in PE‐PEI reaction mixture. Enzyme‐activity curves for jelly fig PE alone and for that in combination with PEI were parallel. Activity of crude PEs (1 U/mL) from tomato, apple, asparagus, and guava was reduced remarkably. Cloud loss of fresh tomato juice, apple juice, and papaya juice was greatly inhibited by PEI (1 mg/mL) during 12‐wk storage.

Effect of temperature on softening and the activities of polygalacturonase and pectinesterase in durian fruit

Abstract Durian fruit (Durio zibethinus Murr. cv Chanee) were ripened at 12, 27 and 34 °C (85±5% RH). When held at 27 °C, the aril of durians softened rapidly, concomitant with a decrease in alkali-soluble pectin, a marked increase in water-soluble pectin and a large increase in polygalacturonase (EC 3.2.1.15) activity. Pectinesterase (EC 3.1.2.11) activity was high at harvest and changed little. Fruit stored at 34 °C showed the same rate of softening as fruit held at 27 °C, whereas polygalacturonase activity (and the amount of water-soluble pectin) was considerably lower. Durians stored at 12 °C showed virtually no softening and had low polygalacturonase and pectinesterase activities and small changes in water-soluble pectin. It is concluded that there is a positive correlation between softening and pectin degradation. No correlation was found between softening and pectinesterase activity, while the softening is correlated with polygalacturonase activity.

Pectinesterase Inhibitor in Rubbery Banana (Musa sapientum L.)

AbstractPectinesterase (PE) (7 U/mL), extracted from ripe and soft banana flesh (RSBF), was prepared with a ratio of 4 parts (1:4) 2% NaCl. PE activity in the 2% NaCl extracted from homogenized RSBF and rubbery banana flesh (RBF) were 7 and 2 U/mL, respectively, during the 16 h PE extraction, suggesting the existence of the PE inhibitor (PEI) in RBF. Crude PEI extracts from RBF and RSBF exhibited about 80% and 17% inhibitory ratios, respectively, on banana PE activity. Crude PEI from RBF, boiled for 30 to 180 min, showed a 79 to 82% inhibitory ratio of banana PE activity.