Honeybee-collected pollen for human consumption: impact of post-harvest conditioning on the microbiota

Bee pollen is gaining attention as functional food for human consumption. However, scanty information is available on the effects of post-harvest conditioning methods on microbial populations associated to bee pollen. Here, we assessed the microbiological quality and safety of bee-collected chestnut and willow pollen processed by different treatments, such as conventional, freeze- and microwave-assisted drying. Conventional drying of chestnut pollen significantly reduced the abundance of aerobic mesophilic bacteria and the contamination by enterobacteria and yeasts. No impact of freeze-drying and microwave-assisted conditioning was found on hygiene indicators. In chestnut pollen, microwave-assisted drying effectively reduced aerobic sporeforming bacteria, while all conditioning treatments strongly decreased coagulase-positive staphylococci. None of the conditioning methods allowed the reduction of moulds contamination and the abundance of sulphite-reducing clostridia. Our findings stress the importance of studying the microbiota of bee-collected pollen for human consumption, in order to process safe pollen with high microbiological quality.