Bee products of Russian regions as sources of carotenoids

The inclusion of pollen and bee bread (fermented pollen) collected by bees in functional foods enriches them with proteins, essential amino acids, carbohydrates, vitamins, micro- and macroelements, phytonutrients, of which carotenoids are the least studied. Their content depends on the geography and ecology of the collection site and storage conditions of the products, but a comparative analysis of the concentration of carotenoids in bee products from different regions of our country is absent in the scientific literature. The purpose of the work is to determine the carotenoid content in beekeeping products of six economic regions of Russia: Central, North-Western, West Siberian, North Caucasian, Ural and Volga. The objects of the study are samples of bee bread, flower pollen, honey enriched with bee bread, propolis, and royal jelly. The sum of carotenoids in the extracts was determined by the method of spectral express analysis by the absorption band of β-carotene (λmax = 450 nm, ε = 139049 l·mol−1·cm−1). In seven out of 15 examined samples of bee bread and pollen purchased in St. Petersburg, the total carotenoid content exceeds their content in carrots, a traditional food source of these nutrients. The highest content was found in samples collected in ecologically safe regions: Pskov (North-Western Economic Region) and Oryol (Central Economic Region). The total carotenoid content in honey and propolis samples is insignificant. No carotenoids were detected in royal jelly using the spectral method. The carotenoid content depends on the duration and conditions of product storage. It was shown that thermostatting bee bread at 37–38 °C for 3; 6; 9 and 12 hours increases the concentration of free xanthophylls as a result of fermentation. Under the same conditions, the total carotenoid content in pollen decreases. Storing bee products for a year at room temperature (25 °C) reduces the total concentration of carotenoids. Bee bread and pollen from six economic regions of Russia have been shown to be a valuable source of carotenoids.