Changes In Polyphenol Oxidase Activities Research Articles

Changes in Polyphenol Oxidase Activity During Rooting of Hardwood Cuttings in Three Grape Rootstocks Under Indian Conditions

Polyphenol oxidase (PPO) activity was investigated during rooting in cuttings from the rootstocks Dog ridge, 110 R and St. George, belonging to different Vitis species. Enzyme activity and rooting ability were analysed. Significant differences were found in PPO activity among different rootstocks, with Dog ridge and 110 R having the highest PPO activity during the initial period of planting, followed by a decrease in enzyme activity. In St. George, the enzyme activity was least during the initial periods, but it increased throughout the experiment. The initiation of rooting primordia was observed until 60 to 90 days after planting in Dog ridge and 110 R rootstocks, while it was observed 120 days after planting in St. George, suggesting differences in the rooting behaviour of the rootstocks. The status of various biochemical components of the mother vines, such as total phenols, reducing sugars, carbohydrates, nitrogen, C:N ratio, etc. were analysed to investigate the influence of these constituents on the rooting ability of the rootstocks apart from PPO activity.

Sonication treatment convalesce the overall quality of hand-pressed strawberry juice

Hand-pressed strawberry juice samples were subjected to sonication treatments (0, 15 and 30min at 20°C, 25kHz frequency). Physicochemical properties (°Brix, pH, water activity, viscosity, titratable acidity, cloud assessment and turbidity), antioxidant compounds and activity (total phenolics, ascorbic acid, anthocyanins, free radical scavenging activity), polyphenoloxidase enzyme activity, browning degree and microbial load were evaluated. Results showed non-significant changes for °Brix, pH, water activity, titratable acidity and colour parameters in sonicated samples compared to control (0min). Sonication treatments resulted in reduced viscosity and increased cloudiness and turbidity. Overall, treatment for 30min showed significant enhancement in bioactive compounds under study. Besides, sonication treatment imparted non-significant changes in polyphenoloxidase activity and in browning degree. However, sonication was incompetent in reducing microbial load. Results generated from this study were encouraging and this is expected to provide platform for future commercial applications on a pilot scale.

Mechanisms of action of aloe polysaccharides and xanthan gum for control of black rot in cauliflower

Black rot is the main bacterial disease of crucifers. The establishment of this disease in the field can result in significant yield losses. The objective of this study was to evaluate the potential of xanthan gum (GUM) and polysaccharides extracted from Aloe barbadensis (aloe polysaccharides—AP) for controlling black rot and eliciting defense mechanisms as well as revealing changes in the physiological behavior of cauliflower. Cauliflower plants were sprayed with distilled water, AP (0.75–6.0mgmL−1) or GUM (0.25–1.5mgmL−1), inoculated with Xanthomonas campestris pv. campestris 4days later and evaluated for disease severity at 14days after inoculation. In vitro bacterial growth in a culture medium containing AP or GUM (0.0 to 3.0mgmL−1) was evaluated for checking the antimicrobial activity of the polymers. Defense mechanisms (hypersensitivity reaction—HR, enzyme activities, content of phenolic compounds and flavonoids) and physiological changes (photosynthetic rate, stomatal conductance and transpiration) were quantified from cauliflower plants treated with distilled water, AP (1.5mgmL−1) or GUM (0.5mgmL−1), inoculated or not with X. campestris. On average, AP reduced bacterial blight symptoms by 68.1% compared to the control. At 0.5mgmL−1, GUM controlled 74.65% of the disease; however, it caused high levels of phytotoxicity on the leaf surface at 1.5mgmL−1. There was no direct effect of polysaccharides on the in vitro growth of X. campestris. Peroxidase activity was increased significantly at 2 and 4days after GUM application, while AP did not change the activity of this enzyme. There were no cells with HR, and no changes in polyphenol oxidase activity, phenolic compound content, flavonoid content or in the antioxidant activity in plants treated with polysaccharides. The photosynthetic rate in plants sprayed with GUM or AP was 22.55% and 39.10% lower, respectively, than the rate of plants treated with distilled water. On average, the polymers reduced conductance by 54.8%. A similar behavior was observed in the transpiration of the plants. Although GUM decreased black rot in cauliflower, it caused signs of stress and phytotoxicity on leaves. By contrast, the application of Aloe barbadensis polysaccharides can be considered as an effective alternative for controlling black rot. This paper also discusses how these polysaccharides reduced the severity of the disease.

Studies on polyphenol oxidase in pomegranate (Punica granatum L.)

The present investigation was undertaken to study properties of polyphenol oxidase and monitor changes in polyphenal oxidase activity in Ganesh cultivar of pomegranate during storage. The characterization of polyphenol oxidase in pomegranate fruit extract with respect to effect of enzyme concentration and substrate concentration was studied. For studying changes in polyphenol oxidase activity during storage, the pomegranate fruits at half yellow stage were freshly harvested and stored at ambient temperature and analyzed after 0, 2, 4, 6, 8 and 10 days of storage. The polyphenol oxidase activity has increased up to 8 th day of storage and thereafter, decreased slightly on 10 th day.

Neodiprion sertifer defoliation causes long-term systemic changes of oxidative enzyme activities in Scots pine needles

The aim of the experiments reported here was to study possible long-term effects of Neodiprion sertifer Geoff. (Hymenoptera: Diprionidae) herbivory, or artificial defoliation, on oxidative enzyme activities in Scots pine (Pinus sylvestris L.) needles as a consequence of induced defense responses. During year 1 (the first season), defoliation by N. sertifer, which feeds on previous season’s needles, did not result in statistically significant changes in polyphenol oxidase activity in the current year’s needles. In contrast, defoliation did lead to increased peroxidase activity in those needles. In the second season (year 2) N. sertifer defoliation of pine seedlings, also defoliated in the previous season either by larvae or artificially, resulted in a decrease of peroxidase activity in the current year’s needles. No significant differences between treatments carried out in year 1 were found in year 2 for peroxidase activity in the previous year’s needles. However, defoliation in year 1 by N. sertifer resulted in decreased needle consumption, and higher mortality of larvae, in year two. These results indicate the existence of long-term changes in needle oxidative enzyme activities as a consequence of N. sertifer feeding.

Inactivation of polyphenol oxidase in muscadine grape juice by dense phase-CO2 processing

Abstract The effect of dense phase-CO2 processing (DP-CO2) on polyphenol oxidase (PPO) activity, polyphenolic and antioxidant changes in muscadine grape juice under different processing pressures (27.6, 38.3, and 48.3 MPa) and CO2 concentrations (0, 7.5, and 15%) were measured. Subsequently two DP-CO2 conditions (48.3 MPa at 0 or 15% CO2) were evaluated for polyphenolic and antioxidant changes during storage (4 °C, four weeks). Pressure alone was responsible for a 40% decrease in PPO activity that resulted in 16–40% polyphenolic and antioxidant losses. Increasing CO2 from 0 to 7.5% was responsible for an additional 35% decrease in enzyme activity and a two-fold greater polyphenolic retention. However, insignificant changes in PPO activity or polyphenolic retention were observed when CO2 was increased to 15%. During storage, juices with residual PPO activity following processing resulted in greater polyphenolic (8- to 10-fold) and antioxidant capacity (four-fold) degradation compared to control juices with no PPO activity. This study demonstrated that partial PPO inactivation can be obtained by DP-CO2 and that CO2 level was the primary variable influencing PPO activity and polyphenolics and antioxidant capacity retention in muscadine grape juice.

POLYPHENOL OXIDASE ACTIVITY IN BANANA CHIPS DURING OSMOTIC DEHYDRATION

ABSTRACT Various treatments were used to determine polyphenol oxidase activity changes during osmotic dehydration of banana slices. A temperature of 35 °C and 5.0 pH were used as the most adequate conditions for polyphenol oxidase activity determination when 4-methyl catechol was used as a substrate. Enzyme activity change was determined in the central and edge region of fruit. The central part of the banana slice showed 2.4 times higher activity than in the edge region. A difference in the kinetics of enzyme activity decrease also occurred during four hours of drying. When the drying was carried out at 70 °C, the enzyme was completely inactivated after 60-90 minutes of specific osmotic treatments. After four hours of osmotic drying at 50 and 60 °C, polyphenol oxidase activity was still present; the residual activity varied from 1.3 to 15 %.

Physiological Attributes Related to Quality Attributes and Storage Life of Minimally Processed Lettuce

Relationships between storage quality attributes, such as russet spotting and browning intensity, and physiological attributes, such as soluble phenolic content and polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) activities, of minimally processed crisphead lettuce (Lactuca sativa L.) were studied. The processed lettuce tissue was kept in air or air plus ethylene at 2 or 5 μl·liter-1 at 2.5 or 5C for 1 to 4 days and then transferred to air at 2.5, 5, or 20C for 1 to several days. None of the above physiological attributes of the initial samples from eight lettuce cultivars (Calmar, El Toro, Sea Green, Pacific, Monterey, Salinas 88, 86-13, and Nerone) and three maturity stages (immature, mature, and overmature) correlated with their storage quality. However, ethylene-induced PPO and PAL activities and browning intensity measured 3 to 4 days after harvest consistently and significantly correlated with the final visual quality of the ethylene-treated, minimally processed lettuce after 6 to 10 days of storage. Among these three attributes, ethylene induced a 2.5- to 5.3-fold increase in PAL activity, while the relative changes in PPO activity and browning intensity were only 23% to 68%. Ethylene-induced PAL activity possibly may be used as an index to predict the storage life of minimally processed lettuce.

The browning capacity of grapes. 1. Changes in polyphenol oxidase activities during development and maturation of the fruit

The browning capacity of grapes. 1. Changes in polyphenol oxidase activities during development and maturation of the fruit

Changes in Polyphenoloxidase Activity and Substrate Levels in Maturing ‘Golden Delicious’ Apple and Other Cultivars1

Abstract Analyses conducted on acetone powder and extracts prepared from ‘Golden Delicious’ apples collected from late July to early September revealed that the polyphenoloxidase (PPO) activity increased during the maturation period while the substrate level decreased. Protein content decreased initially and then increased as the apple approached full maturity. Similar analyses on other cultivars revealed wide variations; ‘Tohoku #3’ had low PPO activity and substrate level which may make this cultivar a good candidate for mechanical harvesting provided it possesses other acceptable horticultural characteristics.

Changes in mulitiple forms of polyphenol oxidase during maturation of tea leaves

Changes in polyphenol oxidase activity during davelopment of tea leaves were investigate by CM-cellulose column chromatography and isoelectric focusing components I-III separate by CM-cellulose chromatography, II and II decreased markedly during maturation. polyphenol oxidase activity was separated int

Changes in Polyphenoloxidase Activity in the Cucumber Mosaic Virus Infected Tobacco Leaves and Its Non-Responsibility for the Changes in Virus Concentration in vivo

The purpose of this study is to find the changes in polyphenoloxidase (PPO) activity in cucumber mosaic virus (CMV) infected tobacco leaves at various periods after inoculation, and to find the effect of this enzyme on the changes in symptoms and virus concentration in vivo, which have been described in previous reports.Lower two leaves of tobacco seedlings (Nicotiana tabacunm L. cultivar Bright Yellow) were inoculated with ordinary strain of CMV (CMV-O), in an air-conditioned glasshouse at 25°C. PPO activity in the systemically infected upper three leaves was measured by the rapid method described by Shiroya, at weekly interval for 4 weeks after inoculation. Chlorogenic aid was used as the substrate of PPO reaction. PPO activity in the leaves increased from the 8th day to the 21st day after inoculation, and on the 14th and the 21st day the activities were significantly higher than those in healthy control leaves. On the 21st day, the difference of activities between infected and healthy leaves was highest, and reached 2.5 times on the basis of tissue dry weight. On the 28th day the enzyme activity decreased to the same level as on the 8th day (Fig. 2). These changes in enzyme activity were inversely proportional to the changes in symptoms and virus concentration in vivo.PPO activity in leaf extracts of tobacco plant grown in copper-deficient culture solution is known to decrease to about 1/10-1/25 of control non-deficient leaves, even when the sign of deficiency is not apparent. Tobacco plants were grown in Cu-deficient cuture solution prepared principally by the method of Staut and Arnon and inoculated with CMV-O. About two weeks after inoculation, greyish brown spots appeared on the lower leaves, as a sign of deficiency. During 4 weeks after inoculation, top leaves were harvested at weekly intervals, and homogenized with phosphate buffer (0.1M, pH 7.0) containing 1/30M Na-diethyldithiocarbamate. Infectivity in Cu-deficient and non-deficient leaves was compared by inoculation onto opposite primary leaves of cowpea. Changes in infectivity of Cu-dificient leaves were similar to those of non-deficient leaves (Fig. 5). Very low infectivity and masking of symptoms in newly developed leaves were obtained on the 21st day, even in Cu-deficient plants. The results were confirmed by using standard inoculum of vacuum-freeze dried infected leaf tissues and by serological assay.When Cu-deficient leaves were homogenized with purified yellow strain of CMV, the infectivity was 2.5-5 times higher than that of control inoculum with non-deficient leaves. In homogenate of Cu-deficient leaves, browning of sap was hardly detectable, whereas the non-deficient leaf sap showed strong browning. These results seem to indicate that deficient leaves has very low PPO activity, in agreement with Shiroya's previous finding.It appears that PPO is not directly responsible for the changes in symptoms and CMV concentration in vivo.