Search results for "Polyphenol oxidase"
showing 7 items of 27 documents
DEGRADATIVE ENZYMATIC ACTIVITIES IN FRESH-CUT BLOOD ORANGE SLICES DURING CHILLED STORED
2009
Summary Blood-orange fruits are suitable to fresh-cut fruit production because of their chemical compositions. Nevertheless, the main limitation of using freshly cut oranges is their susceptibility to juiciness loss and ascorbic acid degradation because of enzymatic alterations. The aim of this work is: to identify some of the enzymes causing the qualitative decay in blood-orange slices during 15 days of chilled storage (at 4 ± 0.5 °C and 85% RH); to investigate the susceptibility to the previous alterations of five blood-orange clones (Moro nucellare, Sanguinello nucellare, Tarocco arcimusa, Tarocco gallo and Tarocco meli) to select the most suitable one for fresh-cut production. The enzym…
SALINITY EFFECTS ON ENZYMATIC BROWNING AND ANTIOXIDANT CAPACITY OF FRESH-CUT BABY ROMAINE LETTUCE (LACTUCA SATIVA L. CV. DUENDE)
2010
Abstract Enzymatic browning is a main problem encountered in minimal processing and further storage of leafy vegetables, leading to shorter shelf-life of products. Changes in the two oxidative activities, polyphenol oxidase (PPO) and peroxidase (POD), as well as in total phenolic content, colour parameters and antioxidant capacity (assayed with ORAC method), were monitored during 10 days of storage at 4 °C of minimally processed baby Romaine lettuce ( Lactuca sativa L. cv. Duende) cultivated under three different salinity conditions (2.8, 3.8 and 4.8 dS m −1 ), in order to determine the most suitable condition for further processing. Increasing levels of salinity reduced both oxidases activ…
Arthropod-induced neoplastic formations on trees change photosynthetic pigment levels and oxidative enzyme activities
2005
Abstract In order to test the hypothesis that arthropod-induced neoplastic formations on trees affect biochemical characteristics of both the newly formed galls and host plant tissues, biochemical characteristics with a possible adaptive role were determined in nine gall-former–host tree combinations. Photosynthetic pigments, extractable protein content, and oxidative enzyme activities were determined in gall tissues, leaf tissues of galled leaves, and leaves on ungalled tree branches. Neoplastic tissues were characterized by a low content of photosynthetic pigments, decreased chlorophyll a/b ratio, lower extractable protein content, and decreased activities of peroxidase and polyphenol oxi…
Wound-induced responses in leaves of strawberry cultivars differing in susceptibility to spider mite
2002
Summary The effect of leaf detachment and wounding on the activities of oxidative enzymes and ethylene production was studied in strawberry (Fragaria × ananassa) cultivars, differing in susceptibility to the spider mite (Tetranychus urticae Koch.). Strawberry plants were cultivated during winter in two growth conditions - with and without overwintering, in greenhouse and laboratory, respectively. Polyphenol oxidase activity, peroxidase activity and catalase activity in strawberry leaves depended on the cultivar analysed, type of treatment (detachment or detachment and wounding), as well as on plant growth conditions. Activities of all analysed enzymes were higher in control plants grown in …
Changes of morphogenic competence in mature Pinus sylvestris L. buds in vitro.
2002
The effects of season and cold storage on morphogenic competence in mature Pinus sylvestris buds were investigated. Peroxidase and polyphenol oxidase activity were measured as markers of oxidative metabolism. No growth in vitro was observed on explants detached from the end of January until the beginning of March. Brachioblasts, each with a couple of needles, formed on 11 % of the buds without macrostrobili that were detached in early April and introduced immediately into culture. Of the explants detached in late July, 15 % formed shoots with brachioblasts and needles. The lowest activity of peroxidase and polyphenol oxidase in pine buds was observed from the end of April until the beginnin…
Comparative effect of supercritical carbon dioxide and high pressure processing on structural changes and activity loss of oxidoreductive enzymes
2019
Abstract Due to the CO2 specific characteristics, it has been used as supercritical (Sc) fluid for several applications, including enzyme inactivation. The influence of Sc-CO2 (10–65 MPa/10–30 min/35–65 °C) on mushroom polyphenol oxidase (PPO) and horseradish peroxidase (POD) was evaluated and the results were compared with those found using high pressure processing (HPP) (200–900 MPa/5–45 °C/1–15 min). The free ion concentration was also studied to compare the enzymatic activity and changes in electrical conductivity. Additionally both enzymes, untreated or treated using either Sc-CO2 or HPP, were used as additives in the CuCl2 crystallization method. The resulting additive-specific CuCl2 …