Principal Supervisor: Dr Kostas Gkatzionis - School of Chemical Engineering
Co-supervisor: Prof Serafim Bakalis
PhD project title: Optimisation of propolis extraction and recovery of high value components
University of Registration: University of Birmingham
A multidisciplinary PhD project is offered at the School of Chemical Engineering, University of Birmingham, aiming to optimise the production and processing of propolis and develop methods for extraction high value high value for use in food, pharmaceutical and cosmetics.
Bees are key to agricultural resilience and food security because production of food depends on pollination. Furthermore, apiculture presents a range of added value products such as bee venom, pollen, honey, royal jelly. In particular, propolis has been widely used in food and cosmetic industry including antimicrobial application and nutritional food supplements.
Propolis is a resinous, strongly adhesive natural apicultural product, mainly composed of plant resins collected from different parts of the plant as buds, buttons, and resins. It is used by bees to protect against invading microorganisms. The action against microorganisms is an essential characteristic of propolis, and have been used by human in pharmaceutical for centuries. The main bioactive components are flavonoids and a wide variety of phenolic compounds. Besides its antibacterial, antifungal and antiviral properties, propolis presents several in vitro and in vivo biological activities including antitumor, anti-hemorrhagic, regeneration of epithelium, reducing cholesterol, hepatoprotective, antioxidant, anti-inflammatory, immunomodulatory and antiparasite activity. These activities are attributed to the content of phenolic compounds and flavonoids. Propolis antioxidant and antimicrobial properties combined with its relatively low toxicity and several of its constituents being present in food and/or food additives, make it suitable preservative in new food applications. Propolis extracts components in pharmaceutical and cosmetic industry of high commercial value and their extraction efficiency, quality and removal of impurities define the biological value of propolis.
The extraction of actives from propolis is heavily based on using organic solvents, mostly ethanol, due to the affinity of its chemical characteristics with the matrix. The extraction conditions such as solvent and temperature have influence on the recovery of flavonoids and phenolic compounds, their antioxidant capacity and biological value. Extraction can be conducted through conventional techniques or alternative methods, such as extraction with supercritical fluid. Advancement of the processing of propolis with new technologies such as supercritical extraction is needed to add value by improving yield, and enchasing the extracts with new properties, while reducing the use of polluting organic solvents.
The objectives of this project will be:
- to optimise the extraction process with focus on preserving the biological value of extracts (flavonoid content, phenolic compounds and antioxidant power) linking to antimicrobial activity;
- understand the full composition and variability of propolis and develop extraction processes that will minimise the loss of active fractions and compounds (ii) explore the effectiveness of already reported and new compounds against microbes (iii) apply tools of bioprocess engineering to develop food, pharmaceutical and cosmetic formulations for encapsulation and delivery of propolis extracts tailored to the applications (food, cosmetics, medical, antibacterial, antifungal, biofilm etc.).
BBSRC Strategic Research Priority: Food Security
Techniques that will be undertaken during the project:
Due to the multidisciplinary approach, the PhD student will develop a wide range of experimental skills. The training objectives will be tailored to the student’s background, skills and interests.
Chemical engineering and bioprocess engineering for extraction of actives. Microbiology for investigation of effectiveness of actives against infection and new antibacterial, antifungal and biofilm applications.
The PhD Student will receive training in: classic microbiology including class 2 pathogens; flow cytometry to analyse bacteria physiology on a single cell level in real time or near-real time through the use of fluorescent dyes and proteins; wet chemistry; antioxidant activity assays; standard analytical techniques such as mass spectrometry and HPLC for characterisation of extracts; key characterisation microscopy techniques ranging from transmission electron microscopy (TEM), scanning electronic microscopy (SEM) to time-lapse combined with fluorescence/confocal microscopy; modelling techniques for capturing microbial growth kinetics and prediction of responses.
Contact: Dr Kostas Gkatzionis, University of Birmingham