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Broccoli (Brassica oleracea var. italica) kept at ambient temperatures after harvest senesce rapidly and sucrose levels decrease. However, if exogenous sucrose is supplied back to the plant, senescence symptoms can be delayed for up to 48 h. Acid invertase enzyme activity increases after harvest in broccoli stored at 20°C and an investigation was undertaken to see if this enzyme has a role in the senescence process. Soluble acid invertase enzyme was extracted from fresh broccoli (0 h) and after 96 h of storage. There were two peaks of invertase activity, one at pH 5–5.5 and the other at pH 8. Broccoli stored in water and sucrose had reduced levels of acid invertase enzyme activity after 48 h compared to those stored dry. Similarly, broccoli kept in a controlled atmosphere (CA) of 10% CO₂ and 5% O₂ senesced at a slower rate and had significantly less acid invertase enzyme activity than air controls after 48 h …