- Title
- Impact of amino acids on postharvest senescence of leafy green vegetables
- Creator
- Sohail, Muhammad
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2022
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Broccoli florets were dipped in three amino acids (AAs); arginine (Arg), cysteine (Cys) and methionine (Met) at concentrations ranging from 1.0 to 100 mM for five min., then stored in plastic containers at 10 °C in air containing 0.1 μL. L-1 ethylene. A 5 mM dip of each AA was found to be optimal in delaying the onset of senescence characteristics, namely loss of green colour, retention of vitamin C and antioxidant (DPPH) activity, and reduced metabolic activity including ethylene production, respiration rate, weight loss, phenylalanine ammonia lyase (PAL) activity and ion leakage. Arg, Cys and Met at 5 mM also delayed senescence in six leafy vegetables; pak choy, coriander, spinach, choy sum, rocket and parsley by enhancing green life, reducing ethylene production and respiration rate except that Met showed no significant effect on the green life, ethylene production and respiration rate of rocket, while for spinach Met only reduced ethylene production and Arg did not affect green life in parsley and ethylene production of rocket. A subsequent study was conducted on broccoli florets dipped in a 5 mM solution of 10 other AAs, namely phenylalanine, glycine, alanine, ornithine, tryptophan, aspartic acid, glutamic acid, serine, tyrosine and valine. Their effect on the postharvest life of broccoli was assessed by loss of green colour (green life), ethylene production, respiration rate and ion leakage. Green life was increased, and ethylene production and ion leakage were decreased by all the AAs except for valine, which was not different to the control, while respiration rate was reduced by all AAs. It is hypothesized that the reduction of ethylene production that occurred soon after treatment may be the mechanism through which AAs delayed senescence. The findings showed that AAs have commercial potential to extend the postharvest life of green vegetables and with their Generally Recognised As Safe (GRAS) status should make them easier to obtain regulatory approval and consumer-acceptance.
- Subject
- broccoli; arginine; cysteine; methionine; postharvest; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1504773
- Identifier
- uon:55570
- Rights
- Copyright 2022 Muhammad Sohail
- Language
- eng
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