Phenolic Composition and Antioxidant Properties of Bee Bread Collected in Three Consecutive Beekeeping Seasons in Poland

Bee bread contains numerous bioactive compounds, including phenolic compounds, which have been associated with antioxidant properties. In this study, we determined the phenolic composition of Polish bee bread collected over three consecutive years using HPLC-DAD. We also measured total phenolic content (TPC) and antioxidant activity, expressed as DPPH radical scavenging activity. The highest concentrations were observed for <i>p</i>-coumaric, <i>trans</i>-ferulic, and caffeic acids, as well as for two flavonoids-rutin and hesperidin. The contents of individual phenolic compounds varied across the years of sample collection, with the exception of <i>p</i>-coumaric and vanillic acids. Despite year-to-year differences in TPC, no significant correlation with antioxidant activity (>90% in all samples) was observed, indicating a substantial contribution of non-phenolic compounds to antioxidant capacity. Principal Component Analysis revealed that almost all samples clustered into three groups according to their year of collection. We conclude that the year-to-year variation in phenolic compound content in bee bread is likely attributable to differences in available pollen sources. Our findings expand the current knowledge of the nutritional value of bee bread produced in Poland and strengthen the premises for its use as a functional food.