The production milk and dairy products made from raw milk of cows or other animals (goat, sheep, camel…) is an agri-food sector with high production volumes and product diversification in all the Mediterranean countries. Milk and dairy products play a role of primary importance in the diet of local consumers of all ages for the supply of essential nutrients such as high biological value proteins, vitamins and minerals. These products also represent a resource for the economic sustenance of marginal areas and, for their high quality and genuineness, deserve a boost for expansion on a global scale market. Also raw milk for direct consumption can be considered a typical product for countries, such as Egypt, where most consumers consider it safer than heat sanitized milk for a deeply-rooted popular belief. However, raw milk, notably due to many microbiological hazards has a very short shelf life leading to waste rejections when milk overproduction is combined with lack of transformation industries and/or bad freezing conditions. Furthermore, hot climate conditions could be a limitation for dairy products conservation. Then, microbiological risks and deterioration processes that can occur in raw milk and derived products pose a public health risk and determine a very short shelf life of the product which is an obstacle for its distribution at longer distances. The project proposed here aims to develop selected simple and efficient methods using natural and safe antimicrobials and/or antioxydants from plants, notably some traditionnaly used for ancestral dairy products, to better protect raw milk from microbial contamination, prior to direct consumption or cheesemaking, by inhibiting pathogenic and spoilage bacteria. The three partners involved will carry out distinct tasks in which they will examine traditional cheesemaking processing involving plants usage in order to evaluate the potential of those plants to favorize their conservation by spoilage and pathogens inhibition. In the same way, plant extracts know for their antimicrobial effect but not yet exploited for dairy productions will be also considers. The objective is to select those that better guarantee safety without inhibiting important microbial components and optimize their use in real production conditions. At the term of the project, the capacity to produce bioactive molecules from plants will be assessed in milk containing microbial associations of pathogenic bacteria of major concern for raw milk and pro-technological bacteria. The antimicrobial treatments that will be found to inhibit undesired microorganisms and not to extensively alter the composition and chemical parameters of milk, will be tested in cheese production trials with real raw milk samples to confirm the advantages of application also at the sensorial level. The project is expected to provide simple methods that can be delivered to small producers to increase safety and quality of raw milk and derived products even in the lack of industrial dairy facilities.

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.