Application des huiles essentielles dans le domaine des embalages alimentaires.

262 p.The overall objective of this work was to study the suitability of Poly Lactic Acid (PLA) and starch containing natural agents, as active packaging. For this, we chose several natural actives substances such as essential oils and plant extracts of rosemary, myrtle, thyme and pistachio tree to produce an active food packaging. Firstly, composition analyses, as well as a phytochemical and biological characterization of these actives substances were elaborated. Secondly, the mode of inclusion of these active agents in PLA and starch matrices and also their potential effects on diverse optical, thermal, mechanical and barrier properties of PLA and starch were investigated. An evaluation of the antifungal and antioxidant activities of these films was studied. Then, a study of the release of the active agents was accomplished from PLA and starch films in contact with a food simulant. The results showed that PLA has the capacity to contain natural active substances and protect food from microbial spoilage. Also, the thermal, the mechanical, and the water vapor barrier properties of PLA were enhanced by the incorporation of commercials essential oils of rosemary (0.5%) and thyme (0.5% and 5%) and the ethyl acetate extracts of thyme (0.5%) and myrtle (0.5% and 1.5%). The incorporation of thyme commercial essential oil into starch film-forming solution, has improved the mechanical and the barriers properties. PLA films containing essential oils and plant extracts have shown promising results to be applied as active food packaging, since they have enhanced the antifungal and antioxidant properties of PLA

Application des huiles essentielles dans le domaine des embalages alimentaires.

262 p.The overall objective of this work was to study the suitability of Poly Lactic Acid (PLA) and starch containing natural agents, as active packaging. For this, we chose several natural actives substances such as essential oils and plant extracts of rosemary, myrtle, thyme and pistachio tree to produce an active food packaging. Firstly, composition analyses, as well as a phytochemical and biological characterization of these actives substances were elaborated. Secondly, the mode of inclusion of these active agents in PLA and starch matrices and also their potential effects on diverse optical, thermal, mechanical and barrier properties of PLA and starch were investigated. An evaluation of the antifungal and antioxidant activities of these films was studied. Then, a study of the release of the active agents was accomplished from PLA and starch films in contact with a food simulant. The results showed that PLA has the capacity to contain natural active substances and protect food from microbial spoilage. Also, the thermal, the mechanical, and the water vapor barrier properties of PLA were enhanced by the incorporation of commercials essential oils of rosemary (0.5%) and thyme (0.5% and 5%) and the ethyl acetate extracts of thyme (0.5%) and myrtle (0.5% and 1.5%). The incorporation of thyme commercial essential oil into starch film-forming solution, has improved the mechanical and the barriers properties. PLA films containing essential oils and plant extracts have shown promising results to be applied as active food packaging, since they have enhanced the antifungal and antioxidant properties of PLA

Characterization of Mediterranean durum wheat for resistance to Pyrenophora tritici-repentis

Tan spot (TS), caused by the fugus Pyrenophora tritici-repentis (Ptr), has gained significant importance in the last few years, thereby representing a threat to wheat production in all major wheat-growing regions, including Tunisia. In this context, we evaluated a Mediterranean collection of 549 durum wheat accessions under field conditions for resistance to Ptr over two cropping seasons in Jendouba (Tunisia), a hot spot for Ptr. The relative disease severities showed significant phenotypic variation from resistance to susceptibility. The correlation between disease scores over the two trials was significant, as 50% of the accessions maintained good levels of resistance (resistant–moderately resistant). Seedling-and adult-stage reactions were significantly correlated. The ANOVA analysis revealed that the genotype term is highly significant at the adult stage, thus emphasizing the high genetic variability of the tested accessions. Reaction-type comparison among and between countries revealed a high diversity of TS resistance. Plant height (PH) was negatively correlated to disease scores, indicating that PH might either have a significant effect on TS severity or that it can be potential disease escape traits. The evaluation of this collection allowed for the identification of potential diverse resistance sources to Ptr that can be incorporated in breeding programs

Synthesis, spectroscopic, and structural characterization of new functionalized gem-bisphosphonate complexes of tin(IV) chloride

The authors are grateful to the Tunisian Ministry of High Education and Scientific Research and Technology for financial support of this researchBisphosphonates of the types X(P(O)(OEt)2)2 (X = CH2=C (1a), CNCH2CH (1b) and PhCH2NCH2CH (1c)) react with SnCl4 in anhydrous dichloromethane to produce the new tin(IV) adducts [SnCl4(1a)] (2a), [SnCl4(1b)] (2b) and [SnCl4(1c)] (2c) in 72-80% yields. These complexes were characterized using IR, multinuclear (1H, 13C, 31P, 119Sn) NMR spectroscopy, elemental analysis, and in one case by single crystal X-ray diffraction. The NMR data show that the bisphosphonate ligands are coordinated to the tin center in a bidentate fashion forming cis octahedral tin complexes. Furthermore, the X-ray structure of complex 2b reveals that the bisphosphonate ligand is coordinated in a bidentate manner to the metal center in a distorted octahedral arrangement with Sn-O-P bond angles in the range 135.95(16)–137.99(18)°. The P=O and Sn-O bond lengths of 1.495(3)-1.497(3) and 2.134(3)-2.146(2) Å, respectively are in the order expected for phosphonate tin(IV) complexes. The results are discussed and compared with closely related analogues.PostprintPeer reviewe

Phenotyping mediterranean durum wheat landraces for resistance to Zymoseptoria tritici in Tunisia

Durum wheat landraces have huge potential for the identification of genetic factors valuable for improving resistance to biotic stresses. Tunisia is known as a hot spot for Septoria tritici blotch disease (STB), caused by the fungus Zymoseptoria tritici (Z. tritici). In this context, a collection of 3166 Mediterranean durum wheat landraces were evaluated at the seedling and adult stages for STB resistance in the 2016–2017 cropping season under field conditions in Kodia (Tunisia). Unadapted/susceptible accessions were eliminated to reach the final set of 1059 accessions; this was termed the Med-collection, which comprised accessions from 13 countries and was also screened in the 2018–2019 cropping season. The Med-collection showed high frequency of resistance reactions, among which over 50% showed an immune reaction (HR) at both seedling and adult growth stages. Interestingly, 92% of HR and R accessions maintained their resistance levels across the two years, confirming the highly significant correlation found between seedling-and adult-stage reactions. Plant Height was found to have a negative significant effect on adult-stage resistance, suggesting that either this trait can influence disease severity, or that it can be due to environmental/epidemiological factors. Accessions from Italy showed the highest variability, while those from Portugal, Spain and Tunisia showed the highest levels of resistance at both growth stages, suggesting that the latter accessions may harbor novel QTLs effective for STB resistance

Improved control of Septoria tritici blotch in durum wheat using cultivar mixtures

Mixtures of cultivars with contrasting levels of disease resistance are capable of suppressing infectious diseases in wheat, as demonstrated in numerous field experiments. Most studies focused on airborne pathogens in bread wheat, while splash-dispersed pathogens have received less attention, and no studies have been conducted in durum wheat. We conducted a two-year field experiment in Tunisia, a major durum wheat producer in the Mediterranean region, to evaluate the performance of cultivar mixtures in controlling the polycyclic, splash-dispersed disease Septoria tritici blotch (STB) in durum wheat. To measure STB severity, we used a novel, high-throughput method based on digital analysis of images captured from 3074 infected leaves collected from 42 and 40 experimental plots on the first and the second year, respectively. This method allowed us to quantify pathogen reproduction on wheat leaves and to acquire a large dataset that exceeds previous studies with respect to accuracy and statistical power. Our analyses show that introducing only 25% of a disease-resistant cultivar into a pure stand of a susceptible cultivar provides a substantial reduction of almost 50% in disease severity. However, adding a second resistant cultivar to the mixture did not further improve disease control, contrary to predictions of epidemiological theory. Susceptible cultivars can be agronomically superior to resistant cultivars or be better accepted by growers for other reasons. Hence, if mixtures with only a moderate proportion of the resistant cultivar provide similar degree of disease control as resistant pure stands, as our analysis indicates, such mixtures are more likely to be accepted by growers

Improving the mechanical performances of a multilayered plate with the orientations of its fibers

International audienc

Durum Wheat Mediterranean Landraces: A Valuable Source for Resistance to Tan Spot Disease

Tan spot (TS), caused by Pyrenophora tritici-repentis (Ptr), has gained significant importance in Tunisia. In this study, a Mediterranean durum wheat collection of 113 accessions were evaluated under field conditions, during the 2018–2019 cropping season, for resistance to Ptr at Koudia experimental station in Bou Salem (Tunisia). The disease progress curve (AUDPC) was used to screen this collection, and the effect of days to heading (DH) and plant height (PH) were evaluated in relation to TS resistance. No significant correlation of PH with AUDPC was found, yet a significant correlation (r = 0.212, p ≤ 0.05) was established between DH and AUDPC scores, suggesting that DH may have an effect on TS development. Moreover, correlation between seedling and adult reactions was significant (r = 0.695, p ≤ 0.001). Although susceptible accessions clustered separately from resistant accessions, the clustering was independent of the country of origin and the status of improvement of the wheat accessions. In total, 67% and 80% of resistant and moderately resistant accessions, respectively, were landraces, suggesting therefore the possible presence of novel sources of resistance to Ptr in some landraces, which can be used to establish a breeding program for resistance to tan spot disease

Potential use of kraft and organosolv lignins as a natural additive for healthcare products

WOS: 000440243600050The growing interest in substituting synthetic products coming from non-renewable sources with products from biomass has focused attention on the lignin biopolymer. Its high availability, low price and properties make the development of new and valuable uses for lignin interesting, thus improving the economic and environmental aspects of the biomass conversion. To achieve this objective, the potential use of industrial kraft and organosolv lignins as antioxidants, antimicrobials and sunscreen products has been evaluated. The results of a detailed antibacterial and antifungal study demonstrated the high potential of kraft lignins against a variety of foodborne and human pathogenic microorganisms. Moreover, both organosolv and kraft lignins presented an effective protection factor (SPF values from 10-20), demonstrating their effectiveness as natural additives for the sun lotion market. In addition, lignin samples presented high antioxidant capacity compared to butylated hydroxytoluene (BHT), one common commercial antioxidant industrially used. Therefore, the development of innovative applications of lignins as a commodity for the chemical, pharmaceutical or cosmetic industries could expand their possible uses in the market giving new added values to lignin.University of the Basque Country [PIF 13/050]; Basque Government [IT1008-16]The authors are grateful for the financial support received from the University of the Basque Country (doctoral grant of Ms Gordobil Grant No. PIF 13/050) and to the Basque Government (scholarship of young researchers training and project IT1008-16)