Characterization of polyphenoloxidase (PPO) and total phenolic contents in medlar (Mespilus germanica L.) fruit during ripening and over ripening

Ayaz, Faik Ahmet; Demir, Orhan; Torun, H; Kolcuoğlu, Yakup; Çolak, Ahmėt

doi:10.1016/j.foodchem.2007.05.096

Cited by 70 publications

(62 citation statements)

References 29 publications

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“…The effect of pH on PPO activity was determined using 100 mM of L-DOPA as substrate and the following buffers (50 mM): glicine-HCl, pH 3.0; sodium acetate, from two to four bands that have also been observed in other fruits, such as papaya [20] and medlar [12]. There are few published studies of PPO isoenzymes in eggplant fruits, and none for the eggplant fruit examined in the present study.…”

Section: Effects Of Ph and Temperature On Ppo Activitymentioning

confidence: 94%

“…Crude enzyme fractions were prepared as described previously elsewhere [12]. Briefly, eggplant fruits (10 g each) were placed in a dewar flask under liquid nitrogen and homogenized at 4°C for 2 min using a blender and 10 mL of ice-cold 50 mM phosphate buffer (pH 7.0) containing 2 mM ethylenediaminetetraacetic acid (EDTA), 1 mM MgCl 2 , 1 mM phenylmethylsulfonyl fluoride (PMSF), 1% (w/v) polyvinylpolypyrolidone (PVPP) and 6% (w/v) Triton X-114.…”

Section: Enzyme Preparationmentioning

confidence: 99%

“…One unit of PPO activity was defined as 1 µM of product formed per mL of reaction medium. Specific activity was defined as units of enzyme activity per milligram of protein [9,12].…”

Section: Enzyme Assaymentioning

confidence: 99%

“…However, cultivar variations and differentiation in genotype affecting the distribution of PPO isoforms have been reported. The development of the ripening stages and the harvesting time also affect the pattern of PPO isoforms [12].…”

Section: Effects Of Ph and Temperature On Ppo Activitymentioning

confidence: 99%

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Characterization of polyphenol oxidase during three ripening stages of an eggplant (Solanum melongena L.) fruit: a local type in northeast Anatolia

et al. 2015

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Characterization of polyphenol oxidase during three ripening stages of an eggplant (Solanum melongena L.) fruit: a local type in northeast Anatolia[Patlıcan (Solanum melongena L.) meyvesinin polifenol oksidazının üç olgunlaşma safhası boyunca karakterizasyonu: Doğu Anadolu' da yerel bir tip] ABSTRACT Objective: A relatively new local type of eggplant, Solanum melongena L. 'Kadife' is widely consumed in Turkey because of its economic availability and good nutritional qualities. However, the high polyphenol content of eggplant renders it susceptible to unattractive oxidative browning catalyzed by polyphenol oxides (PPOs). Therefore, the main aim of this study was to characterize PPO in this eggplant cultivar at three stages of its development. Methods: In this study, we determined substrate specificity, optimum pH and temperature, and optimum substrate concentration of the partial purified eggplant fruits PPO during ripening. Results: L-DOPA was proved to be the preferred PPO substrate in all three stages of ripening. Optimum activity was observed at pH 7.0 for PPO in extracts of ripening and overly-ripe eggplant, while activity in extracts of immature eggplant exhibited a broad pH optimum between, pH 5.0 and 7.0. In general, at all ripening stages, PPO was most active at 30°C and was most sensitive to inhibition by sodium metabisulphite and ascorbic acid. The metal ions (Hg ÖZETAmaç: Kısmen yeni bir yerel tip patlıcan çeşidi Solanum melongena L. 'Kadife', ekonomik uygunluğu ve iyi besin kalitesinden dolayı Türkiye'de yaygın olarak tüketilir. Bununla birlikte, patlıcanın yüksek polifenol içeriği, bu meyveyi polifenol oksidaz (PFO) tarafından katalizlenen istenmeyen oksidatif esmerleşmeye karşı duyarlı kılar. Dolayısıyla, bu çalışmanın temel amacı, gelişiminin üç safhasında bu patlıcan kültivarındaki PFO'yu karakterize etmektir. Metod: Bu çalışmada, olgunlaşma boyunca patlıcan meyvelerinden elde edilen kısmi saflaştı-rılmış PFO'nun substrat özgünlüğünü, optimum pH ve sıcaklığını, ve optimum substrat konsantrasyonunu belirledik. Bulgular: Olgunlaşmanın her üç safhasında, L-DOPA'nın tercih edilen PFO substratı olduğu ortaya konuldu. Olgunlaşmamış patlıcan özütlerinde optimum pH 5.0 ile 7.0 arasında geniş bir aktivite gösterirken olgun ve aşırı olgun patlıcan özütlerindeki PFO aktivitesi için optimum pH'nın 7.0 olduğu gözlendi. Genel olarak, tüm olgunlaşma safhalarında, PFO, 30°C'de en aktiftir ve inhibitör olarak sodyum metabisülfit ve askorbik aside oldukça duyarlıdır. 24, 2015] been named as "Kadife" for years by the local growers in northeast Anatolia (Turkey), at three different stages of maturation. The plant, with its light purple and white striped fruit is widely cultivated and consumed in Trabzon and elsewhere in the region compared to other species. Specifically, our aim was to determine PPO-specific activity from eggplants at time of flowering and at intervals of 2 weeks thereafter. In addition, we studied the effects of pH and temperature, as well as the effects of a variety of inhibitors and metal io...

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Section: Effects Of Ph and Temperature On Ppo Activitymentioning

confidence: 94%

Section: Enzyme Preparationmentioning

confidence: 99%

“…One unit of PPO activity was defined as 1 µM of product formed per mL of reaction medium. Specific activity was defined as units of enzyme activity per milligram of protein [9,12].…”

Section: Enzyme Assaymentioning

confidence: 99%

Section: Effects Of Ph and Temperature On Ppo Activitymentioning

confidence: 99%

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Characterization of polyphenol oxidase during three ripening stages of an eggplant (Solanum melongena L.) fruit: a local type in northeast Anatolia

et al. 2015

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“…The fruits of medlar are used as a nutritional material by local customers and are consumed as marmalade and jellies (Baytop, 1999). It is a very healthy fruit, with phytochemicals including antioxidants (Ayaz et al, 2008;Selcuk and Erkan, 2015). Medlar fruits are used as a treatment for constipation, as a diuretic, and for kidney and bladder stones (Baird and Thieret, 1989).…”

Section: Introductionmentioning

confidence: 99%

Morphological and Chemical Properties of Medlar (Mespilus Germanica L.) Fruits and Changes in Quality During Ripening

Durul¹,

Ünver²

2016

AGR

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Medlar has acquired increasing popularity in recent years for its edible fruits and some healing properties in modern medicine. Medlar fruits are often stored under non-cold conditions in straw. This study was conducted to determine morphological and biochemical characteristics of medlar fruits and changes in fruit quality occurring under ordinary storage conditions. For this purpose, eight types of medlar trees were evaluated. The trees were at a mature stage and productive. Morphological properties such as the fruit and seed weight (g), length, and width (mm) were measured after the harvest. Fruit soluble solid content (%) and pH values were determined at physiological maturity after harvesting, and the fruit soluble solid content was measured again at ripening (edible stage), after 25 days of storage under ordinary storage conditions (mean temperature of 10 °C and mean humidity of 65-70%). Leaf characteristics were also determined. The tree productivity was very different between the types, and it was determined to range from 5.9 and 17.8 kg. The fruit weight varied from 9.69 to 24.45 g, while the water content decreased nearly to the half of the harvest values in some genotypes. The soluble solid content changed depending on the water losses and increased during the ripening period. The seed numbers ranged from 1.7 to 4.7 among the types, and the seed weight varied from 0.12 to 0.45 g. The fruits were able to reach ripening maturity in three weeks under the ordinary storage conditions depending on the type. Thus, this method of storage is practical for the medlar producer, but the results clearly showed that the storage period was too short and that the fruit quality was negatively affected. Cold storage conditions are needed to ensure quality and a long selling time.

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High‐Power Low‐Cost Tissue‐Based Biofuel Cell

Sattayasamitsathit

Jia

et al. 2013

Electroanalysis

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We demonstrate the first example of using plant tissues for the operation of biofuel cells (BFC). A banana tissue rich with polyphenol oxidase (PPO), an enzyme able to reduce oxygen to water, was mixed with a carbon paste (banana/CP). The resulting tissue electrode was employed as the biocathode of a glucose biofuel cell based on a glucose dehydrogenase (GDH) bioanode. On the bioanode, multiwall carbon nanotubes (MWCNTs) are used as supports for the glucose‐dehydrogenase (GDH) biocatalyst and the Meldola’s blue (MDB) mediator, while the phenolic constituents of the banana serve as mediator for PPO. The maximum power output and open circuit voltage (OCV) of the banana‐based tissue biofuel cell were 57 µW/cm2 and 0.46 V, respectively. Control experiments using the corresponding pure enzyme tyrosinase (Tyr) for the biocathode resulted in a substantially lower power output. Cost analysis of this tissue biofuel cell system indicates dramatic improvements in terms of the power‐output/dollar compared to the common use of isolated enzymes (166 502 µW/$ vs. 17.8 µW/$, i.e., 9354 times improvement). The banana‐based biofuel cell displayed an extended lifetime of over 2 weeks with proper storage between experiments. We also demonstrate a fuel‐free full plant‐tissue based BFC concept, combining the banana biocathode with a bioanode based on germinated tomato‐seeds that contain alcohol dehydrogenase (ADH), NAD+ and ethanol. Our findings indicate the potential of using plant tissues for the successful operation of efficient and cost‐effective BFC.

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Characterization of polyphenoloxidase (PPO) and total phenolic contents in medlar (Mespilus germanica L.) fruit during ripening and over ripening

Cited by 70 publications

References 29 publications

Characterization of polyphenol oxidase during three ripening stages of an eggplant (Solanum melongena L.) fruit: a local type in northeast Anatolia

Characterization of polyphenol oxidase during three ripening stages of an eggplant (Solanum melongena L.) fruit: a local type in northeast Anatolia

Morphological and Chemical Properties of Medlar (Mespilus Germanica L.) Fruits and Changes in Quality During Ripening

High‐Power Low‐Cost Tissue‐Based Biofuel Cell

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