Changes in acetaldehyde, ethanol and amino acid concentrations in broccoli florets during air and controlled atmosphere storage.
Hansen, M. E., Sorensen, H. and Cantwell, M.
Postharvest Biology and Technology. Volume 22, Issue 3, July 2001, Pages 227-237.
2001
บทคัดย่อ
Acetaldehyde, ethanol and non-protein bound amino acids were determined in broccoli florets (Brassica oleracea var. italica cv. Marathon) stored for 7 days at 10 deg C in air or controlled atmospheres (0.125, 0.25, or 0.5% O2 alone or in combination with 20% CO2, or 20% CO2 in N2) followed by 2 days aeration. Floret yellowing was visible at days 7 and 9 in air. Low O2 or low O2 plus high CO2 atmospheres delayed yellowing. Acetaldehyde and ethanol concentrations increased as O2 concentrations decreased with or without 20% CO2. Aeration for 2 days generally reduced acetaldehyde and ethanol concentrations. The total free amino acid concentration increased during air-storage from 244 micro mol g-1 dry weight at harvest to 573 micro mol g-1 dry weight at day 9. Due to severe soft rot development in the broccoli treated with 0.125 and 0.25% O2 free amino acids were only determined in samples treated with 0.5% O2, 0.5% O2 + 20% CO2 and 20% CO2. Amino acid change in samples stored under 0.5% O2 were similar to those of air-stored broccoli. Storage for 7 days in the CO2-containing atmospheres resulted in an increase in non-protein amino acids and a decrease in protein amino acids, although total amino acid content remained the same. Alanine accumulated in 0.5% O2 or 20% CO2 in N2 atmospheres. The non-protein amino acid, gamma -aminobutyrate accumulated in 20% CO2 but its concentration decreased upon aeration, and these changes were associated with similar but opposite changes in glutamate concentrations. Aspartate content also decreased in 20% CO2 and increased upon aeration. This coincided with the formation of an unidentified amino acid. In broccoli treated with high CO2 atmospheres, alpha -decarboxylation seemed to be an important path of metabolic interconversion, however, these reaction pathways were reversible upon aeration.