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Freshly harvested marjoram is characterized by an unusually high respiration rate (average at 10°C, 632 W t−1; at 20°C, 1409 W t−1, and at 30°C, 2625 W t−1). These comparatively high levels were maintained throughout a postharvest period of 72–80 h. The values declined only to 49, 39 and 42% of the initial rate for each temperature range, and even at 30°C there was no respiratory collapse despite notable senescence and wilting. The greatest decrease in the rates occurred during the first 18 h after cutting. The ensuing dry matter loss was relatively high, as was transpiration (at 10°C, 1.53% of the fresh matter was lost in 24 h). The essential oil balance measured over the postharvest period at 10 and 20°C increased slightly (10%). At 30°C, majoram herbs (1st cut) which had been harvested near the optimal date (10–30% flowering) contained 22% more essential oils than dried, freshly harvested material; physiologically younger plants (2nd cut) showed even a 35% increase. In some cases the proportion of cis-sabinenic hydrate and sabinenic hydrate-acetate increased slightly at 20 and 30°C, while there was only a minor influence on γ- and α-terpinenes and 4-terpineol. Colour and exterior quality were best maintained, as in dried material, when the herbs were held at 10°C throughout the postharvest period. |
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