The agrorefinery concept, i.e. valorization of entire plants by sequential extractions of molecules of interest while not penalizing the subsequent valorization of residual by-products as biosourced molecules (antioxidant or biocides ones), is based on the Green Chemistry concept and fited with the requirements of Sustainable Agriculture.
In the framework of AROMATIC and MYCOVAL regional programs, various Midi-Pyrénées medieval (forgotten) aromatic and medecinal plants (Achillea millefolium, Calamintha grandiflora, Tanacetum balsamita, Myrrhis odorata, Tussilago farfara etc.) and undervalorized wild mushrooms (e.g. Phaeolus schweinitzii, Inonotus hispidus, Tricholoma columbetta, Tricholoma caligatum, Xerocomus chrysenteron, Hydnellum ferruginemum etc.) were agrorefined.
As a case study, Aubrac Tea aka Great Calamint (Calamintha grandiflora), belonging to the Labiatae family was selected for application of agroreffinery concept to aromatic montaineous plants. Labelled as medieval aromatic plant, great calamint grown in firtree and beech forests as well in Aubrac mountains at 1500 meters elevation (southern Massif Central of France) than in lithuanian landfields (150 meters elevation). It is a perennial herb having a strong and penetrating mint odor which was presently famous for its use as a condiment in French “Nouvelle Cuisine” by Michelin three stars cook Michel Bras.
According to agrorefinery scheme, essential oils and aromatic extracts of french and lithuanian great calamints were first extracted by hydrodistillation from leaves, flowers and roots. Chemical constituents were characterized by GC-FID and GC-MS. Then, in order to study the chemical potential of by-products, the residues obtained after hydrodistillation were separated into liquid and solid fractions. The solid fraction was dried and then extracted in cascade with acetone, methanol and ethanol, while the liquid fraction (aromatic waters) was freeze-dried and spray-dried. The antioxidant potential of different plant extracts, including essential oils, were evaluated by using different in vitro assays. Two main antioxidant activity tests were employed: i) assays to evaluate oxidation of fats, oils and other fat containing foods (Oxipress); ii) assays to evaluate radical scavenging activity in model systems (DPPH, ABTS, FRAP). Antioxidant activities were expressed as gallic acid equivalents (GAE) to standardize these methods and to allow data comparisons.