Physiological postharvest responses of Matricaria (Matricaria recutita L.) flowers

Mechanically gathered fresh Matricaria (Matricaria recutita L.) flowers had a very high respiration rate (average from six trials at 10 degreesC: 999 +/- 134 W t(-1), at 20 degreesC: 2438 +/- 289 W t(-1), and at 30 degreesC: 4552 +/- 570 W t(-1)). These levels, comparatively high for medical or vegetable plants, were maintained throughout an 80-h postharvest period. A senescence-related decline was only observed at 10 degreesC by 33.3%, at 20 degreesC by 45.4% and at 30 degreesC by 62.0% of their initial rate for each temperature level. Even at 30 degreesC, no respiratory collapse occurred despite considerable senescence and strong wilting of the flowers. Spring-sown crops had significantly higher respiration rates at harvest (+ 86-333 W t(-1)) than the autumn-sown crop and maintained this difference until the end of 80 h storage. The senescence-associated decrease occurred more quickly at 20 degreesC and even more so at 30 degreesC in autumn-sown plants. The ensuing dry matter loss was relatively high (7.5%/80 h) as was transpiration (1.83% in 24 h) at 10 degreesC. Constituents of Matricaria flowers decreased only slightly during 80 h postharvest storage: essential oils (up to 20%), chamazulene (10%), EN-IN-dicycloether (20%) and apigenine-7-glycoside (20%). The valuable (-)-alpha -bisabolol and its A and B oxidized forms, in contrast, responded rather differently at 10 degreesC with losses between 10 and 80%. All these changes were primarily dependent on storage temperature and the annual growing conditions. Matricaria flowers need intensive and immediate postharvest treatment including ventilating, cooling or drying. The expected respiration heat release in these trials may be used for process calculations. The essential oils and most of the pharmaceutical constituents were best maintained in the flowers at 10 degreesC; but for bisabolol and its oxides, 20 degreesC and for dicycloether, 30 degreesC are more favourable temperatures. (C) 2001 Elsevier Science B.V. All rights reserved.