Uncovering proteome variations and concomitant quality changes of differently drying-treated rape (Brassica napus) bee pollen by label-free quantitative proteomics

High moisture content of fresh bee pollen makes it difficult to preserve and thus makes drying a necessary process during the bee pollen production. Drying treatment will affect its quality and the effects of sun drying, hot-air drying and freeze drying on the proteome of rape (Brassica napus) bee pollen have been evaluated using label-free quantitative proteomics by liquid chromatography-tandem mass spectrometer (LC-MS/MS). A total of 8377 proteins are identified, among which the most abundant differential proteins were found in freeze drying-treated samples. Also freeze-drying treatment maximizes the content of antioxidant, antibacterial and anemic bioactive pollen protein. Besides, rape bee pollen is found to adjust its metabolism to protect itself during the drying process. These results can be favorable to evaluate the effects of drying treatment on the nutrition and function of processed rape bee pollen and insight into how rape bee pollen proteins respond to dehydration.