1.4.2. Drying

Apart from drying soft bee stages and tissues on collection cards, bulk samples of whole bees can also be freeze-dried, or lyophilized. Lyophilization is a convenient way to store samples long-term at room temperature and preserves the chemical integrity of most compounds, although some functional activity may well be lost. Freeze-drying/lyophilization requires a specialized instrument that draws a vacuum while the samples are kept below the point where solid and liquid phases can co-exist (below -50oC), so that the ice sublimates, i.e. changes directly to vapour without melting first. Any biological sample can be lyophilized and the instructions for this come with the particular lyophilizing apparatus. It should be noted here that reconstituted dried tissue is fundamentally different from frozen wet tissue, with different and more variable recovery efficiencies for the different biomolecules than for fresh tissues. Lyophilized samples are stored at room temperature in a sealed box with desiccating packages, to prevent re-hydration.