Antimicrobial plant phenolic compounds for food preservation – ACTIPHEN

The scientific strategy is based on the integration of the skills of a multidisciplinary research consortium gathering analytical chemistry (University of Toulouse & ISA, Université Lyon 1), food microbiology (BioDyMIA), polymeric materials science and technology (BioDyMIA, PTI Alimentec & Addikem/Addiplast) and chemometrics (ISA) skills. Selection of plant extracts following pre-screening is based on their antimicrobial activity against foodborne pathogenic and food-spoiling microorganisms, their harmlessness (tested by performing in vitro cytotoxicity assays), their physico-chemical properties (solubility, oxygen sensitivity…) and their chemical composition. The combination of experimental design and chemometrics approaches allows selecting adapted extraction/fractionation processes and assessing the “chemical composition - activity of extracts” relationships for their bio-guided fractionation.

Experiments with an array of 117 known plant phenols (stilbenes, benzoic and cinnamic acids, coumarins, flavones,etc.) having different physico-chemical properties and a large antimicrobial activity spectrum were also conducted. The set of data obtained thus has been exploited for a QSPR (Quantitative Structure-Property Relationship) approach to determine the structure-reactivity and antimicrobial activity relationships of phenols under different conditions.
Most of studies dealing with antimicrobial activity of plant extracts were performed in vitro in microbiological culture media. These media have a less complex structure and composition than food matrices. Therefore, antimicrobial activity of plant extracts and phenols selected following pre-screening were assessed with food-mimicking matrices (e. g. microbiological culture media supplemented with proteins and/or dispersed fat in order to assess the effect of interactions of phenols with these food constituents on their antimicrobial activity).

Known plant phenols and extracts are melt blended in polymers with different melting temperatures and polarities (polypropylene (PP), linear low density polyethylene (LLDPE), ethylene vinyl acetate (EVA)) to obtain antimicrobial materials. This part of Actiphen project is performed by Addikem/Addiplast (a masterbatch producer), BioDyMIA (antimicrobial materials characterization), the technological innovation platform (PTI) “Perception, quality and safety of packed foods” (Alimentec) and University of Toulouse (analytical chemistry). Moreover, the surface chemical analysis skills (XPS, ToF-SIMS) of ISA allows studying the distribution and the state of association of phenols in the superficial part of materials. Migration of phenols from polymeric matrices in which they will be incorporated to food-mimicking solvents or matrices placed in direct contact is also studied.

Articles in international peer-reviewed scientific journals

Léonard L., Bouarab Chibane L., Ouled Bouhedda B., Degraeve P., Oulahal N. (2016). “Recent advances on multi-parameter flow cytometry to characterize antimicrobial treatments.” Frontiers in Microbiology 7, article n° 1225 (review)

Bouarab-Chibane, L., Ouled-Bouhedda B., Léonard, L., Gemelas, L., Bouajila, J., Ferhout, H., Cottaz, A., Joly, C., Degraeve, P., Oulahal, N. (in press). Preservation of fresh ground beef patties using plant extracts combined with a modified atmosphere packaging. European Food Research and Technology. DOI 10.1007/s00217-017-2905-3. (original research article)

Article in a national peer-reviewed journal

Oulahal N., Bouarab Chibane L., Léonard L., Trinh Thi Thanh N., Degraeve P. (2017). Les extraits végétaux : une alternative à certains conservateurs et biocides ? Industries Alimentaires et Agricoles, Février-Mars, 12-15.

Communications in international congresses

Bouajila J., Herzi N., Camy S., Romdhane M., Condoret J.S. (2015). Comparison of different methods for extraction from medicinal plants: Yield, chemical composition and biological activities. International Conference on Food Chemistry & Technology, November 16-18, San Francisco, USA. (oral communication)

Bouarab Chibane L., Degraeve P., Oulahal N. (2017). Monitoring the response of Staphylococcus aureus to antimicrobial plant phenolics by multiparameter flow cytometry. FEMS 2017, 7th Congress of European Microbiologists, July 9-13, Valencia, Spain. (poster)

ACTIPHEN aims at assessing the potential of plant extracts (eucalyptus, green tea, pomegranate, grape, prune …) containing antimicrobial phenols with a molecular mass between 150 and 3000 g.mol-1 for food preservation. This choice is based on following observations:
- (i) antimicrobial activity of plant phenols has been less studied than their antioxidant activity
- (ii) essential oils are the plant extracts which were the most studied for their antimicrobial activity. Moreover, besides having a higher cost than other plant extracts (due to their lower yield), essential oils contain volatile compounds (thus frequently generating off-odors) and with a low water solubility. These 2 factors often limit their use for food preservation.
The plant extracts tested (selected and prepared by Nat’ex Biotech company and IMRCP laboratory, Université Toulouse 3) will in priority be by-products of fruits and edible aromatic and medicinal plants (leaves, peels,…). The application-oriented goals of Actiphen project are the selection of plant extracts suitable for incorporation (i) directly in perishable foods (e. g. raw meat) or (ii) into food contact materials (e. g. active packaging).
The scientific strategy is based on the integration of the skills of a multidisciplinary research consortium gathering analytical chemistry (IMRCP & ISA, Université Lyon 1), food microbiology (BioDyMIA), polymeric materials science and technology (BioDyMIA & a sub-contractor) and chemometrics (ISA) skills. Selection of plant extracts following pre-screening will be based on their antimicrobial activity against foodborne pathogenic and food-spoiling microorganisms, their harmlessness (tested by performing in vitro cytotoxicity assays), their physico-chemical properties (solubility, oxygen sensitivity…) and their chemical composition. The combination of experimental design and chemometrics approaches will allow selecting adapted extraction/fractionation processes and assessing the “chemical composition - activity of extracts” relationships to guide their fractionation.
Experiments with an array of known plant phenols having different physico-chemical properties and a large antimicrobial activity spectrum will also be conducted. The set of data obtained thus will be exploited for a QSAR (Quantitative Structure-Activity Relationship) approach to determine the structure-reactivity and antimicrobial activity relationships of phenols under different conditions.
Most of studies dealing with antimicrobial activity of plant extracts were performed in vitro in microbiological culture media. These media have a less complex structure and composition than food matrices. Therefore, antimicrobial activity of plant extracts and phenols selected following pre-screening will be assessed with food-mimicking matrices (e. g. microbiological culture media supplemented with proteins and/or dispersed fat in order to assess the effect of interactions of phenols with these food constituents on their antimicrobial activity).
Known plant phenols and extracts will be melt blended in polymers with different melting temperatures and polarities (polypropylene (PP), low density polyethylene (LDPE), ethylene vinyl acetate (EVA)) to obtain antimicrobial materials. This part of Actiphen project will be performed by Addikem (a masterbatch producer), BioDyMIA (antimicrobial materials characterization), a sub-contractor like the technological innovation platform (PTI) “Perception, quality and safety of packed foods” (Alimentec) and IMRCP (analytical chemistry). Moreover, the surface chemical analysis skills (XPS, ToF-SIMS) of ISA will allow studying the distribution and the state of association of phenols in the superficial part of materials. Migration of phenols from polymeric matrices in which they will be incorporated to food-mimicking solvents or matrices placed in direct contact will also be studied.