An improved method for pollen analysis of honey

Abstract

Filtration, rather than centrifugation, was investigated as a first step to extract pollen from honey. The filter with adhering pollen and spores was then acetolyzed in a 1.5 ml microcentrifuge tube to speed up the remaining steps of sample preparation. Various filters were tested and only those in polyester, cellulose, and cellulose acetate and poly-acetate had no deleterious effect on pollen acetolysis. Among these, fast filtration of diluted 10 g honey samples was possible with polyester and cellulose acetate filters, but polyester fibers trapped some pollen. Cellulose acetate membranes 47 mm in diameter with 0.8 μm pores (Sartorius SM111-04-47N) permitted the filtration of honey samples in less than 3 min and the filters dissolved totally during acetolysis releasing the pollen. With these filters, a new method based on filtration and followed by acetolysis in microcentrifuge tubes was developed and compared with standard pollen analysis starting with centrifugation at 1700 g (3000 rpm) for 10 min. Pollen recovery assays were conducted with a mountain honey and a test honey made of pollen-free honey to which pure pollen of Castanea, Helianthus, and Lilium was added. Significantly more pollen was recovered with the new method than with the usual one with both honeys. Also, the pollen spectrum of the test honey treated with the new method was similar to that of the pollen added originally, while it was significantly different when the test honey was processed with the standard method. Thus the new method significantly improved pollen extraction quantitatively and qualitatively, while decreasing sample preparation time by 50% and using less reagents and cheaper equipment.