Pyrethrum

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A Note on the Possibility of the Stabilization of Pyrethrum
(January 1948) Raymond, W.D.; Padhye, V.P.; F.R.I.C., Chemical Laboratory, Dar es Salaam
Following work [1] oh the stabilizing effect of sulphur dioxide on papain, our attention sk as drawn to a paper by Mario Covello [2] on the inactivation of the oxidases in pyrethrum flowers with the resultant stabilization of the dried product. Covello's work was carried out on flowers in different stages of development and by different methods of drying. The development stages were:—(1) the dlosed flower heads, the heads just opened, the head completely opened, more matured flowers than No.-3,'(5) the heads completely mature and, partly, dried on the plant.
Pyrethrum Drying
(1937) Kenya Agricultural Research Institute; Department of Agriculture Kenya
When first the subject of the artificial drying of pyrethrum was raised, the only information available was to the effect that drying at a temperature of 40º C. (104ºF.) caused no loss of pyrethrins. Accordingly, it was recommended that drying houses should be run at temperatures between 100 and 105 0 F. For weather, produced very dingy flowers various reasons, discussed below, drying was very slow, and soon higher temperatures were being employed. Drying houses run at over 150º F. have been It is strongly recommended that the visited.