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Subject: search.filters.subject.Polyphenol oxidase

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    Lotus flower extract as a natural anti-browning agent for fresh romaine lettuce (Lactuca sativa L. var. longifolia)
    (2023-11-01)
    Pradabkun, N.
    ;
    Yeamsuriyotai, K.
    ;
    Teerarak, M.
    ;
    Saetiew, K.
    The effect of lotus (Nelumbo nucifera Gaertn.), butterfly pea (Clitoria ternatea) and Siam tulip (Curcuma sessilis) aqueous extract on reduction of polyphenol oxidase (PPO) and peroxidase (POD) in romaine lettuce (Lactuca sativa L. var. longifolia) were evaluated. Results showed that in vitro lotus flower aqueous extract exerted the highest reduction of PPO and POD activities on the romaine lettuce. The effectiveness of in vivo application of lotus flower aqueous extract to control browning cut stem ends of fresh romaine was examined. Romaine lettuce harvested as a whole plant and cut off at the stem. Cut stem ends of romaine lettuce were dipped in various concentrations of lotus flower extract for 5 min and packaged in polypropylene plastic bags. Weight loss, color, browning index as well as PPO and POD activities were evaluated during 12 days of storage at temperature of 10±2°C and relative humidity 50±5%. Cut stem ends dipped in 0.5% aqueous extract of lotus flower resulted in inhibition of browning of cut stem ends and decrease in PPO and POD activities. Thus, exogenous 0.5% aqueous lotus flower extract treatment could be a useful application to alleviate browning in cut stem ends of fresh romaine lettuce.
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    Changes in the activity of enzymes associated with enzymatic browning and chemical composition during Musa sapientum Linn. 'Kluai Khai' banana fruit ripening
    (2023-07-01)
    Makboriboon, N.
    ;
    Teerarak, M.
    ;
    Saetiew, K.
    The results showed that the initial firmness of banana fruit harvested at the raw stage was 7 N and decreased to less than 2 N at overripe and very ripe stages. The total soluble solids increased throughout the ripening period, whereas the titratable acidity maintained a high level during the ripening process. The banana peel stayed green during the raw stage, and the yellow color formed between the unripe stage to the overripe stage. The lightness of the banana peel increased from the raw stage to the ripe stage, decreased at the overripe stage, and then dropped sharply at the very ripe stage. This color change was linked to the browning incidence of the fruit peel and an increasing browning area and soluble browning pigment content. The PPO and POD showed a low activity at the raw stage and then increased with advancing ripening and maintained a significantly higher level than the raw fruit. The findings of this study exhibited that the ripening stages of the 'Kluai Khai' banana influence the firmness, peel color, and browning incidence of the fruit peel and the polyphenol oxidase and peroxidase activities.
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    Browning inhibition on fresh-cut apple by the immersion of liquid endosperm from mature coconuts
    (2020-12-01)
    Supapvanich, Suriyan
    ;
    Yimpong, Aiyarath
    ;
    Srisuwanwichan, Jiraporn
    The application of natural antibrowning agents for fresh-cut products has been recently considered. This study manifested the efficiency of coconut liquid endosperm, coconut water (CW), from mature tall (cooking) coconut (C-CW) and yellow dwarf coconut (Y-CW) on browning inhibition of ‘Gala’ apple wedges during storage at 4 ± 1 °C for 9 days. The apple wedges were immersed in water (control), C-CW or Y-CW for 1 min. The visual appearance, superficial colour attributes, browning pigment concentration, total phenols concentration, polyphenoloxidase (PPO) activity and reducing antioxidant capacity of apple wedges were monitored. Moreover, antioxidant activity of both C-CW and Y-CW was also observed. Antioxidant activity of Y-CW was higher than that of C-CW. Both of the CW immersions maintained visual appearance, whiteness and lightness values as well as delayed the increased yellowness and brownness values of hypanthium (flesh) and mesocarp (core) of apple wedges. The browning pigment concentration and PPO activity were obviously lowered by both CW immersions. Total phenols concentration and antioxidant activity of C-CW and Y-CW immersed apple wedges were higher than those of control samples. In conclusion, both of the mature coconut liquid endosperms are feasible natural agent inhibiting browning incidence of fresh-cut fruits during storage.
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    Effect of silver particle-longkong peel extract coating on postharvest decay and browning in longkong fruit
    (2020-01-01)
    Lichanporn, Intira
    ;
    Techavuthiporn, Chairat
    ;
    Wongs-Aree, Chalermchai
    We aimed to assess the effect of longkong peel extract (LPE)-silver particle-alginate coating on the postharvest decay and browning of longkong fruit during storage at 13°C and 90–95% relative humidity (RH). Longkong was coated with 0, 0.45 or 0.90 mg·L−1 LPE in silver particle-alginate solution and then stored at 13°C and 90–95% RH for nine days. In the mixture consisting of the longkong peel extract and silver solution, the silver particle size was modified to yield fine particles. Electron micrography showed the presence of silver particle sizes ranging in size from approximately 71–625 nm. Fruit coated without LPE exhibited severe browning, weight loss and decay incidence during storage. Coating with 0.45 and 0.90 mg·L−1 LPE significantly inhibited the increase in fruit browning by mainly reducing peroxidase (POD) and polyphenol oxidase (PPO) activities. LPE coating effectively reduced the longkong weight loss and decay incidence. No fruit treatment showed a significant titratable acidity change or increased soluble solids at the end of storage. These results indicate that coating with LPE is a promising approach to inhibit decay and browning and to maintain the quality of longkong during low-temperature storage.
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    Effects of methyl jasmonate on physicochemical qualities and internal browning of ‘queen’ pineapple fruit during cold storage
    (2017-10-01)
    Boonyaritthongchai, Panida
    ;
    Supapvanich, Suriyan
    The effects of methyl jasmonate (MeJA) as a protectant against chilling injury on physicochemical qualities of ‘Trad-see-thong’ pineapple (‘Queen’ group) fruit was investigated. The pineapple fruit were immersed in 1 mM MeJA for 5 min and then stored at 10 ± 1°C for 20 days. MeJA had no effect on respiratory rate and pulp colour, but suppressed ethylene production during cold storage. Weight loss, ion leakage (IL), internal browning (IB), and loss of pulp firmness were inhibited by MeJA. The MeJA treatment also suppressed the reduction of lightness (L*) and yellowness (b*) and the increase of total phenols (TP) that commonly occurs during cold storage, and increased the polyphenol oxidase (PPO) activity of pulp adjacent to the core (PAC) tissue. Certain bioactive compounds, such as ascorbic acid (AsA) and superoxide dismutase (SOD) in PAC tissues were enhanced by MeJA. No significant difference in peroxidase (POD) activity in both pulp and PAC tissues were detected between the treated and control fruits. These results suggest that immersion in MeJA is an effective means to maintain quality, alleviate IB symptoms, and enhance certain bioactive compounds in ‘Queen’ pineapple fruit cv. Trad-see-thong during cold storage.