Samak Kaewsuksaeng

Thaksin University, Badalung, Phatthalung, Thailand

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Publications (6)9.21 Total impact

  • Postharvest Biology and Technology 01/2015; 100:1–7. · 2.45 Impact Factor
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    ABSTRACT: UV-B irradiation was applied to lime fruit to investigate its effect on chlorophyll (Chl)-degrading enzyme activities and postharvest quality during storage. Mature green lime fruit were irradiated with or without UV-B doses at 19.0 kJ m−2 and then stored at 25 °C in darkness. UV-B treatment efficiently delayed the decrease of hue angle values and Chl a contents. The activities of the Chl-degrading enzymes, chlorophyllase, Chl-degrading peroxidase and pheophytinase in the fruit with UV-B treatment were suppressed and Mg-dechelation activity was also retarded by the treatment. UV-B treatment induced a gradual increase in citric acid and suppressed the increase of sugar contents during storage. In addition, the ascorbic acid content with or without UV-B treatment decreased during storage, but the decrease in the control was faster than that with UV-B treatment. We concluded that UV-B treatment effectively suppressed chlorophyll degradation through the control of chlorophyll-degrading enzyme action and the changes in quality in mature green lime during storage.Highlights► UV-B treatment was effective in retarding degreening in green lime fruit during storage. ► UV-B treatment suppressed chlorophyll degradation through the control of activities of the chlorophyll-degrading enzymes, chlorophyllase, chlorophyll-degrading peroxidase, pheophytinase and Mg-dechelation. ► Quality of lime fruit treated with UV-B was maintained during storage.
    Postharvest Biology and Technology 01/2011; 61(2-3):124-130. · 2.45 Impact Factor
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    ABSTRACT: UV-B irradiation was applied to broccoli florets to investigate its effect on chlorophyll degradation and chlorophyll-degrading enzyme activities in stored broccoli. Broccoli florets were irradiated with UV-B doses at 4.4, 8.8, and 13.1kJm−2 and then kept at 15°C in darkness. We found that a UV-B dose of at least 8.8kJm−2 efficiently delayed the decrease of the hue angle value and the contents of chlorophylls a and b. Chlorophyllide a and 132-hydroxychlorohyll a gradually decreased with senescence. Pheophorbide a and pyropheophorbide a levels were significantly higher in broccoli without UV-B treatment. Chlorophyllase and chlorophyll-degrading peroxidase activities with UV-B treatment were suppressed, as well as the activity of Mg-dechelatase. Mg-dechelating substance activity was also suppressed with this treatment. We concluded that UV-B treatment effectively suppressed chlorophyll degradation in broccoli florets during storage, suggesting that the effect could be due to the suppression of chlorophyll-degrading enzyme activities.
    Food Chemistry 01/2010; 120(3):645-651. · 3.33 Impact Factor
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    ABSTRACT: The effects of heat treatment on the formation of chlorophyll (Chl) derivatives and Chl-degrading enzyme activities in stored broccoli (Brassica oleracea L. Italica Group 'Ryokutei') florets were determined. The Chl a level barely changed during heat treatment, but each Chl a derivative level changed. Chlorophyllide (Chlide) a, pheophorbide (Pheide) a, C13 2 -hydroxychlorophyll (C13 2 -OHChl) a, Chl a', an isomer of Chl a, and pheophytin (Phy) a were detected as a Chl derivative during heat treatment and during storage after treatment. Chlide a, Pheide a, and C13 2 -OHChl a levels decreased during 2-h heat treatment (50°C), whereas Chl a' and Phy a levels increased. Chl-degrading enzyme activities, in particular, Mg-dechelation activity, were effectively suppressed after 2 h of heat treatment. The content of Chls a and b in control broccoli florets decreased greatly during storage at 15°C, while the content in heat-treated broccoli florets hardly changed at all. In Chl derivatives, the Pheide a level in broccoli florets treated with or without heat treatment, especially the former, increased appreciably during storage. The Chlide a level in control florets decreased markedly during storage. On the other hand, the Chlide a level in heat-treated broccoli florets did not change during storage. Mg-dechelation activity in control florets markedly increased after 4 days of storage at 15°C, but the enhancement of the activity was suppressed by heat treatment. These findings suggest that Chl derivatives, especially Pheide a, are accumulated as intermediates in heat-treated broccoli florets, and Mg-dechelating action, in conjunction with that of chlorophyllase and Chl-degrading peroxidase, could be involved in Chl degradation in stored broccoli florets.
    Journal- Japanese Society for Horticultural Science 01/2007; 76:338-344. · 0.96 Impact Factor
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    Samak Kaewsuksaeng
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    ABSTRACT: One of the symptoms of senescence in harvested horticultural crops is the loss of greenness that comes with the degradation of chlorophyll. With senescence, the chlorophyll-degrading enzyme activities such as chlorophyllase, Mg-dechelatase or Mg-dechelation activity, a new chlorophyll-degrading enzyme, pheophytinase, pheophorbidase and chlorophyll-degrading peroxidase, which are involved in chlorophyll degradation, affected greatly in stored horticultural crops. The chlorophyll derivatives, especially chlorophyllide, pheophytin, pheophorbide and C13 2 -hydroxychlorophyll are accumulated as intermediates of chlorophyll degradation. In addition, chlorophyll degradation by the chlorophyll-degrading enzymes seems to occur in the thylakoid and envelope membrane of chloroplast and/ or the vacuole. The involvement of chlorophyll-degrading enzymes in senescing horticultural crops is also discussed.
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    ABSTRACT: The effects of heat treatment on the formation of chlorophyll (Chl) derivatives and Chl-degrading enzyme activities in stored broccoli (Brassica oleracea L. Italica Group ‘Ryokutei’) florets were determined. The Chl a level barely changed during heat treatment, but each Chl a derivative level changed. Chlorophyllide (Chlide) a, pheophorbide (Pheide) a, C132-hydroxychlorophyll (C132-OHChl) a, Chl a′, an isomer of Chl a, and pheophytin (Phy) a were detected as a Chl derivative during heat treatment and during storage after treatment. Chlide a, Pheide a, and C132-OHChl a levels decreased during 2-h heat treatment (50°C), whereas Chl a′ and Phy a levels increased. Chl-degrading enzyme activities, in particular, Mg-dechelation activity, were effectively suppressed after 2 h of heat treatment. The content of Chls a and b in control broccoli florets decreased greatly during storage at 15°C, while the content in heat-treated broccoli florets hardly changed at all. In Chl derivatives, the Pheide a level in broccoli florets treated with or without heat treatment, especially the former, increased appreciably during storage. The Chlide a level in control florets decreased markedly during storage. On the other hand, the Chlide a level in heat-treated broccoli florets did not change during storage. Mg-dechelation activity in control florets markedly increased after 4 days of storage at 15°C, but the enhancement of the activity was suppressed by heat treatment. These findings suggest that Chl derivatives, especially Pheide a, are accumulated as intermediates in heat-treated broccoli florets, and Mg-dechelating action, in conjunction with that of chlorophyllase and Chl-degrading peroxidase, could be involved in Chl degradation in stored broccoli florets.