Maria Leja

Antioxidant ability of broccoli flower buds during short-term storage

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).

The Content of Phenolic Compounds and Radical Scavenging Activity Varies with Carrot Origin and Root Color

The contents of phenolic compounds and radical scavenging activities were assessed in a carrot collection comprising 35 cultivars, landraces and breeding populations. The accessions originated from various world regions and they represented Eastern and Western carrot gene pools. In two-year field trial carrot roots of orange, red, yellow, white and purple color were cultivated, freeze-dried and analyzed for phenolic content by Folin-Ciocalteu assay and UV/Vis assay. Radical scavenging activity in the extracts was determined with a stable DPPH radical. Carrots developing purple roots possessed on average 9 times more phenolics than roots of other colors. Furthermore, they were rich in anthocyanins that caused very high antiradical activity. Red carrots showed higher antioxidant activity than orange, yellow and white carrots and in the season of lower rainfall they accumulated higher amounts of phenolic compounds. Carrots of Asian origin belonging to Eastern gene pool were more often purple or red and richer in phenolics and had higher antiradical activity than those from the Western gene pool with mainly orange roots.

Phenolic metabolism in root slices of selected carrot cultivars

Carrot root slices, stored for 4 days at 20 °C reacted with a strong accumulation of total phenols, especially chlorogenic acid. A significant accumulation of isocoumarin content within the peel was observed in stored slices. Synthesis of phenols was accompanied by an increase in phenylalanine ammonia lyase activity, wound induced respiration and ethylene production.The great variability among the studied four cultivars was found concerning isocoumarin synthesis, PAL activity, respiration rate and ethylene evolution, but less distinct in the case of chlorogenic acid accumulation.The carrot slices obtained from freshly harvested roots were more sensitive to mechanical damage and short-term storage than those prepared from roots previously stored.

Callitriche cophocarpa — a new rich source of active phenolic compounds

This study was focused on the analysis of the contents (by HPLC-DAD) and antioxidant activity of phenolic compounds of aquatic higher plant Callitriche cophocarpa. The novelty of the work was: 1) the study of the species which is almost unknown in the context of investigations of bio-active compounds and, 2) the application of a unique L-band electron resonance spectroscopy (L-band EPR) to measure antioxidant activity of samples. The results were compared with those obtained for microalgae Chlorella and Spirulina which are widely distributed as the diet supplements. The obtained results are very promising with respect to the freeze-dried material of Callitriche, which revealed both high level of phenolic compounds (33 mg g−1 dry weight) and antioxidant activity (0.14 g of reduced DPPH· g−1 dry weight). An isoform of sinapic acid appeared to be the main fraction in this sample. The average content of the total phenolic compounds in Callitriche freeze-dried samples was ca. 43 or 25 times higher than in the case of the Chlorella or Spirulina samples, respectively. These samples showed also 16 times lower scavenging activity in relation to freeze-dried Callitriche material.

The effect of preliminary chilling of broccoli transplants on some antioxidative parameters

Abstract The aim of this study was to introduce older transplants of broccoli into field conditions to shorten their growing period and to obtain a crop with a high nutritive value. The additional storage of relatively old (four- and eightweek- old) transplants in a cold chamber before planting in the field shortens the growing period; however, it can influence the chemical composition of the leaves and heads. According to earlier research, the preliminary chilling of transplants affected the high yielding of broccoli; a determination of the quality of plants, including select health-promoting properties, was necessary for their full characteristics. In the present work, the four- and eight-week-old broccoli transplants were kept at 2°C either for one or two weeks before planting in the field. Catalase (CAT) and peroxidase (POD) activity as well and the accumulation of phenolic compounds were determined in the leaves of the transplants before and after chilling. The same parameters were detected in the leaves and heads of broccoli at harvest time. The effect of low temperature treatment on CAT activity was observed only at the stage of transplants; however, the increased activity of POD stimulated by chilling was maintained during the growing period until the harvest. The reaction of the plants to low temperatures can be connected with their mechanism against stress conditions and seems to vary in the case of those antioxidative enzymes. The effect of chilling on the accumulation of phenolics (total, cinnamic acid derivatives, flavonols) was noted only in transplants and was not evident during the harvest. The differences observed between the individual seasons of the experiment, both in enzyme activity and synthesis of phenolics, were most likely caused by the differing climatic conditions

Some antioxidant and senescence parameters of broccoli as related to its developmental stages

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.

Effect of Maturity Stage and Short-Term Storage on the Biological Quality of Sweet Pepper Fruits

Effect of Maturity Stage and Short-Term Storage on the Biological Quality of Sweet Pepper Fruits Sweet pepper plants of Spartacus cultivar were grown in plastic tunnel on rockwool using the fertigation technique. The three year experiment was carried out in 2006-2008. Fruits were harvested every year in three maturity stages: green, turning and red. The contents of ascorbic acid, phenols, soluble sugars, nitrate and ammonium ions, total nitrogen, free amino acids and dry matter were determined in freshly harvested fruits as well as after short-term (two weeks) storage. Red pepper fruits accumulated significantly more ascorbic acid, soluble sugars and phenols in comparison with the green and turning ones. The level of nitrate ions was highest in the green fruits and decreased during their ripening while the ammonium ion concentration increased. The lowest content of amino acids was observed in green fruits. Two week storage at 5-8°C, followed by two days at room temperature caused the reduction of nitrate ions in green and red fruits. Ammonium ion content as well as phenol and soluble sugar level increased in stored fruits, irrespectively of their maturity stage. Ascorbic acid content increased in the stored turning and red pepper fruits as related to its initial concentration. Dry matter content did not change after storage. Biological quality of harvested pepper fruits depended of their maturity stage, however, their response to short-term storage was similar. Wpływ Fazy Dojrzałości Oraz Krótkotrwałego Przechowywania na Jakość Biologiczną Owoców Papryki Słodkiej Paprykę słodką ‘Spartacus’ uprawiano w tunelu wysokim na wełnie mineralnej z wykorzystaniem systemu fertygacyjnego. Doświadczenie przeprowadzono w latach 2006-2008. Owoce papryki zbierano w trzech fazach dojrzałości: zielone, przebarwiające się oraz czerwone. W materiale roślinnym oznaczono zawartość kwasu askorbinowego, sumy fenoli, cukrów rozpuszczalnych, azotanów i jonów amonowych, a także azotu całkowitego, wolnych aminokwasów i suchej masy. Analizy przeprowadzono tuż po zbiorze owoców, a także po ich krótkotrwałym przechowywaniu. W czerwonych owocach papryki oznaczono istotnie więcej kwasu askorbinowego, cukrów rozpuszczalnych i fenoli niż w owocach zielonych czy przebarwiających się. Zawartość azotanów była najwyższa w owocach zielonych i obniżała się w trakcie dojrzewania, podczas gdy zawartość jonów amonowych rosła w trakcie wybarwiania się owoców. Najniższym poziomem wolnych aminokwasów charakteryzowały się owoce zielone. Owoce papryki przechowywano dwa tygodnie w temperaturze 5-8°C, a następnie dwa dni w temperaturze pokojowej. Przechowywanie wpłynęło na obniżenie zawartości jonów azotanowych w zielonych i czerwonych owocach papryki. W trakcie przechowywania zwiększała się zawartość jonów amonowych, fenoli i cukrów rozpuszczalnych niezależnie od stopnia dojrzałości. W przypadku owoców przebarwiających się i czerwonych obserwowano wzrost zawartości kwasu askorbinowego w trakcie przechowywania. Nie notowano natomiast zmian w zawartości suchej masy w owocach papryki. Wartość biologiczna papryki była zależna od fazy dojrzałości owoców w momencie zbioru, podczas gdy w trakcie przechowywania notowano podobne zmiany składników niezależnie od fazy dojrzałości.

Phenolic compounds as the major antioxidants in red cabbage

Abstract In the heads of four red cabbage cultivars and two DH lines (one of red and one of white type), as well as in the standard white cabbage ‘Lennox F1’ cultivar, the contents of phenolic substances (total, phenylpropanoids, flavonols and anthocyanins) were estimated. Antiradical scavenging activity was determined using the DPPH and ABTS methods. The level of phenolics of all the groups, especially that of the anthocyanins, as well as RSA, was much higher in red cabbage in comparison to white. Among red cabbage assays, also a considerable variability of antioxidative parameters was observed. Four-month commercial storage resulted in a significant reduction in phenol compounds in red cabbage, but this was not the case in the white cultivar. Radical scavenging activity did not significantly change after cold storage, except in 2005/06, when a decrease in RSA measured by the DPPH method was noticed. The values of RSA determined by the ABTS method exceeded those determined by DPPH.

Some nutritional constituents in bulbs of selected Allium cultivars

Abstract Two years experiment was carried out to compare the nutritional composition in bulbs of ten onion cultivars grown in the field conditions. Pyruvic acid, ascorbic acid and soluble sugars were determined in the edible part of onion bulbs. In most cultivars the content of pyruvate as the pungency index was ranged between 3-7 μmol g-1 fresh weight (medium pungency), however, three of them exceeded 7 μmol g-1 fresh weight (high pungency). A higher level of pyruvate corresponded in most cases with higher sugar content but was not correlated with that of ascorbic acid.

The effect of various light conditions and different nitrogen forms on nitrogen metabolism in pepper fruits

Abstract The ‘Spartacus’ F1 sweet pepper was grown in a plastic tunnel on rockwool during 2006-2008. A fertigation technique was used for water and fertiliser application. The tunnel was divided into two parts covered with different plastic films. The first part of the tunnel was covered with a film that transmitted less light than the film covering the second part. In both parts of the tunnel, the plants were divided into two groups. One group of plants was fertilised with just nitrate nitrogen (100% N-NO3) and the other one with three forms of nitrogen (N-NO3:N-NH4:N-NH2 in a ratio of 50:13:37). Fruits were harvested mature green and red. Concentrations of nitrate and ammonium ions as well as total nitrogen and free amino acids were analysed in the plant material. Nitrate and nitrite reductase activities were also investigated, and dry matter content and soluble sugars were also determined. Higher light intensity increased nitrate concentration in red pepper fruits but decreased ammonium ion content. These tendencies were not as obvious in green fruits. In most cases, red fruits fertilised with three nitrogen forms accumulated more nitrates than those fertilised with N-NO3. This observation was similar in the case of green fruits. In most cases, pepper fruits accumulated more ammonium ions in the case of N-NO3 fertilisation than when three forms of nitrogen were applied, but the differences were not always statistically significant. Higher nitrate reductase activity was observed in the case of better light conditions as well as mixed nitrogen fertilisation in red pepper fruits. No differences were observed in the case of nitrite reductase activity between fruits harvested from various treatments in red and also green fruits, with some exceptions. The green fruits of pepper had higher nitrate reductase activity than the red ones. It can be summarised that various light conditions influenced the nitrogen metabolism of pepper fruits as well as the different nitrogen forms applied with fertilisers.