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M. Nieves Criado, M. José Motilva, Tomás Ramo, and M. Paz Romero

The aim of this study was to monitor the pigment profile and chlorophyllase (Chlase) and lipoxygenase (Lox) activities of olive (Olea europaea L.) drupes during the development of the fruit from `Arbequina' and `Farga' in order to find better ways to characterize cultivars such as `Arbequina' that produce virgin olive oils that are highly appreciated in international markets. `Farga' was included as a comparative reference. The total pigment content in olive drupes from the two cultivars studied suffered a decrease when the maturation process began, the rate of chlorophyll degradation being more marked than that of the carotenoid pigment. Chlorophyllides a and b, cis-α-carotene, β-cryptoxanthin, and esterified xanthophylls were detected only in `Arbequina' fruit. The behavior of the Chlase and Lox activities in both cultivars was different. Chlase activity in olives from `Farga' was detected only at the end of the pit hardening period, but in the case of `Arbequina' the presence of dephytilated chlorophyllic derivatives is directly related to a higher Chlase enzymatic activity than that of `Farga' fruit. Although the level of these enzymatic activities decreased when ripening advanced in both cultivars, in `Arbequina' both enzymes showed a slight increase of activity at the latest stages of ripening.

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Naoki Yamauchi and Alley E. Watada

Degradation of chlorophyll in spinach (Spinacia olearacea L. cv. Hybrid 612) appeared to be regulated through the peroxidase-hydrogen peroxide pathway, which opens the porphyrin ring, thus resulting in a colorless compound. This conclusion was arrived at from the analysis of chlorophylls (Chls) and their metabolizes by HPLC and of enzyme activities catalyzing the degradative reactions. Chls decreased at 25C but not at 1C. The chlorophyll oxidase pathway was not active, as noted by the lack of accumulation of a reaction product named Chl a-1. Lipid peroxidation increased with storage, but the products of the reaction. did not degrade chlorophyll, as noted by the lack of increase in Chl a-1. Chlorophyllase activity increased, but chlorophyllide, the expected product of the reaction, changed minimally during senescence. Ethylene at 10 ppm did not alter the pathway that degraded chlorophyll in spinach.

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Zisheng Luo

Mei (Prunus mume `Daqinghe') fruit were immersed in 20 °C (control), 47 °C (HWT47), 50 °C (HWT50), or 53°C (HWT53) water for 3 min after harvest, then stored at 20 °C. Firmness, peel color, chlorophyll, chlorophyllase activity, soluble solids content (SSC), titratable acidity (TA), respiration, ethylene production, and pectinmethylesterase (PME) and polygalacturonase (PG) activity were monitored to determine the effects of hot water treatment in delaying fruit ripening. Control fruit displayed a typical climacteric pattern of respiration and ethylene production. Peak CO2 production and ethylene production were observed 6 days after harvest. Fruit softening was accompanied by decreases in hue angle, chlorophyll content, SSC, and TA and increases in chlorophyllase and PME and PG activity. Hot water treatment delayed the onset of the climacteric peaks of CO2 and ethylene production. The delays were associated with delays in fruit softening, consistent with lags in the rise of PME and PG activity; delays in yellowing and chlorophyll breakdown, consistent with lags in the rise of chlorophyllase activity; and delays in loss of SSC and TA. The shelf life of fruit increased by 6 days, or 60%, with HWT47, and by 8 days, or 80%, with HWT50 or HWT53.

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Naoki Yamauchi, Xiao-Ming Xia, and Fumio Hashinaga

Effects of flavonoid pigments on chlorophyll (Chl) degradation by Chl peroxidase in the flavedo of Wase satsuma mandarin (Citrus unshiu Marc. var. praecox Tanaka) fruits were studied. Chl was degraded when hydrogen peroxide was added in a reaction mixture containing Chl and a phosphate buffer extract from the flavedo. Chlorophyllide, which was formed by the action of chlorophyllase in the extract, was also degraded. The flavonoid contents decreased with the Chl degradation in the reaction mixture. Analysis of the flavonoid with HPLC showed that hesperidin and narirutin were contained in the flavedo as a major flavonoid, and that the former decreased significantly and the latter showed almost no change with the Chl degradation in the reaction mixture. In the ethylene-treated fruits, the hesperidin content in the flavedo also decreased with the degreening of stored fruits, suggesting that the flavonoid oxidation by Chl peroxidase could be involved in the Chl degradation.

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Ron Porat, Xuqiao Feng, Moshe Huberman, David Galili, Raphael Goren, and Eliezer E. Goldschmidt

'Oroblanco' is an early-maturing pummelo-grapefruit hybrid (Citrus grandis Osbeck × C. paradisi Macf.). The fruit are usually picked and marketed while the peel color is still green; however, in some cases they can lose this green color during postharvest shipping and storage, which diminishes their commercial value. The effects of storage temperatures, gibberellic acid (GA), ethylene, and 1-methylcyclopropene (1-MCP) on the degreening of 'Oroblanco' fruit were examined. Storage temperature was critical for retaining fruit color: at 2 °C the fruit remained green for a period up to 5 weeks, whereas at storage temperatures of 6, 12, and 20 °C there was a progressive increase in the rate of degreening. Applications of GA, either as preharvest sprays or as postharvest dip treatments, effectively retained the green fruit color. Ethylene exposures up to 100 μL·L-1 for 3 days had only a slight effect on fruit degreening, and 1-MCP treatments up to 200 nL·L-1 for 16 hours had no effect at all. The slight influence of ethylene and the ineffectiveness of 1-MCP on fruit color change can not be attributed to difficulties in their application, since in the same experiments ethylene markedly induced peduncle abscission, and 1-MCP effectively inhibited this ethylene effect. Accordingly, ethylene had only a relatively small effect on the induction of chlorophyllase enzyme activity in green 'Oroblanco' peel tissue.

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Hirofumi Terai, Hironobu Tsuchida, Masashi Mizuno, and Yumi Fukui

Green broccoli (Brassica oleracea L. Italica Group) flower heads were stored in perforated polyethylene bags at 20C. Green color of sepals in broccoli flower buds changed to yellow and individual flower buds wilted gradually during storage. Chlorophyllase activity in flower buds tended to increase and chlorophyll content decreased during senescence. Optical and scanning electron microscopic observations were conducted to elucidate the structural changes of chloroplasts in sepals of broccoli flower buds through the senescence. The chloroplasts observed with optical microscope were fine and green when the stage of broccoli flower buds was all green. However, at half-yellow stage, the shapes of chloroplasts obscured and the green color faded. After this stage, colored small particles appeared in the cells and the number of particles tended to increase as yellowing of the flower buds progressed through the senescence. Scanning electron micrographs indicated that the small particles were formed in the chloroplasts and come out from them with senescence followed by aggregation with each other.

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Greg McCollum and Pilar Maul

., 1986 ; Goldschmidt et al., 1977 ; Purvis and Barmore, 1981 ; Shimokawa et al., 1978 ). The effect of ethylene on color change in citrus fruit has been shown to be related to an increase in chlorophyllase activity ( Purvis and Barmore, 1981

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Xingbin Xie, Congbing Fang, and Yan Wang

nonfluorescent catabolites ( Krautler, 2008 ). Dephytilation by chlorophyllase (CHL) is the first step in chlorophyll a degradation, producing pheophorbide ( Harpaz-Saad et al., 2007 ). A proposed alternative pathway for producing pheophorbide from chlorophyll

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Zhi-Rong Li, Kang-Di Hu, Fen-Qin Zhang, Shi-Ping Li, Lan-Ying Hu, Yan-Hong Li, Song-Hua Wang, and Hua Zhang

harvesting complex to Chls ( Hörtensteiner and Kräutler, 2011 ). The enzymes named, non-yellow coloring 1 (NYC1), chlorophyllase (CLH), pheophytinase (PPH), pheophorbide a oxygenase (PaO), and RCC reductase (RCCR), serially degrade Chl b to “primary

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Eliezer E. Goldschmidt

the chloroplasts are transformed into carotenoid-rich chromoplasts. This is a partially reversible environmentally, nutritionally, and hormonally controlled process ( Goldschmidt, 1988 ), which involves ethylene-induced upregulation of chlorophyllase