Twenty five double haploid (DH) lines of white cabbage were examined and compared with their parental lines as well as with two cabbage cultivars (‘Lennox F1’ and ‘Attraction F1’) regarding their antioxidative capacity. Ascorbic acid, total phenols and radical scavenging activity (RSA) were determined both in freshly harvested cabbage heads and after long-term (4 months) storage. The great variability of ascorbic acid and phenol contents was observed in plants of DH lines. The RSA was relatively low, however, differed among the investigated lines and cultivars. Cold storage caused the significant increase of all detected parameters. High content of soluble phenolics and ascorbic acid was accompanied by high antiradical activity only in some of the investigated DH lines and in the ‘Lennox F1’ cultivar. Maria Leja, Anna Mareczek, Adela Adamus, Piotr Strzetelski, Michal Combik 32

The herbs of lemon balm, oregano, and peppermint were analysed immediately after harvest and after drying to determine their antioxidant activity and content of total phenolics, l-ascorbic acid, and carotenoids. The strongest inhibition of linoleic acid (LA) peroxidation was found for fresh and dried oregano. For peppermint and lemon balm it was significantly lower and decreased after drying. The ability to scavenge the free radical DPPH (2,2-diphenyl-1-picrylhydrazyl) was very high in almost all tested samples, exceeding 90%. The three species tested had a very high content of total phenolics and drying of oregano and peppermint resulted in their considerable increase. The highest content of ascorbic acid was determined in fresh peppermint and lemon balm and carotenoid content was at a similar level in all the species tested. Drying caused great losses of these compounds.

Phenolic constituents (total phenols, phenylpropanoids, flavonols and anthocyanins) and antioxidant ability were determined in bee pollen of 12 plant species. Antioxidant ability was measured as total antioxidant activity, radical-scavenging activity and activity against free hydroxyl radical. Great variability of phenolic contents was observed in the pollen of investigated species. Total antioxidant activity differed considerably (0.8–86.4% inhibition of lipid peroxidation), however, in most of the examined pollens, it was high and corresponded with the phenylpropanoid level.Great differences in the radical-scavenging activity (8.6–91.5% of DPPH neutralization) and in the hydroxyl radical-scavenging activity (10.5–98% inhibition of deoxyribose degradation) were observed and were not correlated with the content of phenolic compounds.In most of the investigated plant species, antioxidative capacity of bee pollen was very high.

The superoxide dismutase (SOD) and the antiradical activity (RSA) together with the phenylopropanoids, flavonoids and chlorophyll levels in flower bud tissue were estimated during short-term storage of broccoli Lord cultivar. Catalase (CAT) and peroxidase (POD) activities were detected in broccoli flower branchlets. The activity of SOD increased gradually at both storage temperatures (20 and 5°C), while the RSA increased only in higher temperature. Increase in catalase activity was observed after 1-day storage of non-packaged broccoli at 20°C, followed by its decrease, and after 1- and 3-day storage of the packaged heads. In the case of low temperature the enzyme activity increased only after 10 days of storage. Storage of broccoli at room temperature caused the significant increase of peroxidase activity, while at low temperature (5°C) activity of the enzyme rose after 10 days. During the storage, the accumulation of phenylopropanoids and flavonoids in broccoli flower buds was observed. The rapid decrease of chlorophyll was observed only in the case of broccoli heads stored at 20°C. Applying of polyethylene foil to packaging of broccoli heads during storage in most cases decreased the SOD, CAT, POD antiradical activities and phenol content, and slowed down chlorophyll decomposition in flower buds. The obtained results emphasize the active role of antioxidant components of broccoli flower buds senescing during short-term storage, especially in intense stress conditions.

The antioxidant capacity was determined in the peel of two apple cultivars (Jonagold and S'ampion) stored for 120 days at 1 degreesC, either in the regular cold chamber or in CA (2% CO2/2% O-2). During long-term cold storage as well as during an additional 7 day storage of fruits at 16 degreesC, total phenols, total antioxidant activity (TAA), and radical scavenging activity (RSA) increased considerably, irrespective of the storage conditions. A slight decrease in anthocyanins was observed in apples stored in air, while the CA treatment did not cause any significant changes. Increase of soluble peroxidase (POD) activity was much stronger in apples kept in air than in CA, while, after a subsequent 7 day storage at high temperature, a further increase in enzyme activity was observed in all treatments. The high activity of polyphenoloxidase (PPO), determined in freshly harvested fruits, dropped to low (Jonadgold) or undetectable (S'ampion) levels after cold storage, both in the regular chamber and in CA, and increased slightly after the high temperature treatment. In the stored fruits a marked ethylene evolution was found, especially when stored in air. (C) 2002 Elsevier Science Ltd. All rights reserved.

Stress of mechanical damage (cutting) caused metabolic changes of phenol compounds in carrot. The level of soluble phenolics and responsible for the bitter taste isocoumarin increased in the root slices obtained by the crosswise cutting and stored for three days at room temperature. These changes were accompanied by the increase in phenylalanine ammonia lyase activity, the key enzyme in phenylpropanoid synthesis. One of the responses to root injury was also stress ethylene evolution. The higher sensitivity to wounding stress was in most cases presented by the roots attacked previously by the carrot fly (Psila rosae). Mechanical damage of carrot roots during the growing period (pest feeding) as well as during harvesting, transportation and the initial processing can affect significantly biological and nutritional quality of carrot, particularly in case of inadequate storage and handling conditions.

In broccoli heads grown in spring and in autumn, and harvested at four various developmental stages antioxidant ability as well as certain indices of plant senescence were investigated. Development of broccoli heads was accompanied by losses of chlorophyll and ascorbic acid. At pre-florescence stage accumulation of soluble phenolics was observed. Activity of peroxidase in the initial stage of growth increased significantly and its high level was mantained during the whole growing period. The profound evolution of ethylene was manifested by plants of the pre-florescence stage.In broccoli grown in spring the higher contents of chlorophyll and phenolics in comparison with the autumn experiment were observed, as well as slightly higher activities of peroxidase and catalase. Total antioxidant activity was considerably higher in spring than in autumn.

Some metabolic changes in broccoli heads stored under commonly-applied conditions were investigated. Freshly harvested broccoli of Lord cultivar were stored at 20°C and at 5°C for 3 and 7 days, respectively, either non-packaged or packaged in polymeric film samples. Short-term storage at room temperature induced accumulation of total phenols, especially in non-packaged broccoli. With low-temperature treatment, phenol content rose only after 7 day storage of non-packaged heads. Both low temperature and application of polymeric foil stopped losses of ascorbic acid. Total antioxidant activity increased considerably during storage in all treatments. Changes of fatty acids were manifested as a slight decrease in saturated fatty acids in cold storage and increase of polyunsaturated fatty acids in most treatments. Metabolism of fatty acids did not correspond to thiobarbituric acid-reactive substances (products of lipid peroxidation).