Antibacterial activity and bee-derived protein content of honey as important and suitable complementary tools for the assessment of honey quality

Honey possesses health-promoting properties; however, industrial processing and manipulation of raw honey can harm on its biological activities, including antibacterial activity. Therefore, this study aimed to compare the honey's antibacterial activity, its total protein content, and the abundance of the most dominant bee-derived proteins in honey between raw (n = 92) and supermarket (n = 17) samples. We showed that tested raw honey samples were much more effective in inhibiting the growth of Staphylococcus aureus, a model bacterium, at a median minimal inhibitory concentration (MIC) value of 4.5 % compared to supermarket honey samples ceasing bacterial growth at median MIC value of 36 %. Moreover, raw honey samples, tested in this study, contained significantly higher amounts of total protein as well as the content of particular bee-derived proteins (major royal jelly protein 1 (MRJP1), glucose oxidase (GOX), and alpha-glucosidase) in contrast to supermarket honey samples. These data hint that some supermarket honey samples exhibited strikingly low protein content. Furthermore, alpha-amylase (diastase) from Aspergillus oryzae was found in the supermarket sample characterised with the lowest protein content. Our findings highlight the burning need to refine and monitor the specific quality parameters, ensuring the authenticity of honey and maintaining its reputation as a functional food.