We collect our propolis both with traps and by hand, and it is all inspected and cleaned of debris before extraction into ethanol. Our tinctures are approximately 30% propolis by weight and 70% ethanol.
A journal article with a brief history as well as summary of propolis studies and properties can be found by following the link below.
http://dx.doi.org/10.1155/2013/964149
Further peer-reviewed articles are cited as follows:
2. Grange, J M., and R W. Davey. "Antibacterial properties of propolis (bee glue)." Journal of the Royal Society of Medicine, vol. 83, 1990, pp. 159-60, doi: 10.1177/014107689008300310.
3. Marcucci, MC. "Propolis: chemical composition, biological properties and therapeutic activity." Apidologie, vol. 1995, no. 26, 1995, pp. 83-99.
4. Khodabakhski, Darioush, et al. "In vitro and in vivo performance of a propolis-coated polyurethane wound dressing with high porosity and antibacterial efficacy." Colloids and Surfaces B: Biointerfaces, vol. 178, 1 June 2019, pp. 177-84, doi:10.1016/j.colsurfb.2019.03.010.
5. Siheri W., Alenezi S., Tusiimire J., Watson D.G. (2017) The Chemical and Biological Properties of Propolis. In: Alvarez-Suarez J. (eds) Bee Products - Chemical and Biological Properties. Springer, Cham
6. Farooqui, T., and Akhlaq A. Farooqui. (2017) Therapeutic Effects of Propolis on Neurological Disorders. In: Farooqui, T. (eds) Neuroprotective Effects of Phytochemicals in Neurological Disorders. Wiley-Blackwell.
7. Peycheva, Stela, et al. "Effect of Bulgarian propolis on the oral microflora in adolescents with plaque-induced gingivitis." Revista Brasileira de Farmacognosia, vol. 2018, 5 Dec. 2018, doi:10.1016/j.bjp.2018.11.001.
8. Anjum, Syed I, et al. "Composition and functional properties of propolis (bee glue): A review." Saudi Journal of Biological Sciences, vol. 2018, 17 Aug. 2018, doi:10.1016/j.sjbs.2018.08.013.
9. Asgharpour, Fariba, et al. "Chemical composition analysis and in vitro investigation of cytotoxic and antioxidative activities of Iranian propolis against breast cancer cell line, MCF-7." Chemistry Select, vol. 3, no. 39, 22 Oct. 2018, doi:10.1002/slct.201802457.
10. Sforcin, J M. "Propolis and the immune system: a review." Journal of Ethnopharmacology, vol. 113, no. 1, 15 Aug. 2007, pp. 1-14, doi:10.1016/j.jep.2007.05.012.
11. Viuda-Martos, M, et al. "Functional properties of honey, propolis, and royal jelly." Journal of Food Science, vol. 73, no. 9, 3 Nov. 2008, doi:10.1111/j.1750-3841.2008.00966.x.
12. Park, Eun-Hee, and Ja-Hoon Kahng. "Suppressive effects of propolis in rat adjuvant arthritis." Archives of Pharmacal Research, vol. 22, no. 554, Dec. 1999.
