Extracts of different parts (heads, bracts and stems) of Cynara cardunculus L. (cardoon) and Cynara scolymus L. (globe artichoke), obtained by two different extraction techniques (Ultrasound-Assisted Extraction (UAE) and classical extraction (CE)) were examined and compared for their total phenolic content (TPC) and their antioxidant activity. Moreover, infusions of the plant’s parts were also analysed and compared to aforementioned samples. Results showed that cardoon’s heads extract (obtained by Ultrasound-Assisted Extraction) displayed the highest TPC values (1.57 mg Gallic Acid Equivalents (GAE) g⁻¹ fresh weight (fw)), the highest DPPH^• scavenging activity (IC50; 0.91 mg ml⁻¹) and the highest ABTS^•+ radical scavenging capacity (2.08 mg Trolox Equivalents (TE) g⁻¹ fw) compared to infusions and other extracts studied. Moreover, Ultrasound-Assisted Extraction technique proved to be more appropriate and effective for the extraction of antiradical and phenolic compounds. Graphical Abstract

The global turn from the linear to the circular economy imposes changes in common activities such as food packaging. The use of biodegradable materials such as polyvinyl alcohol, natural raw materials such as clays, and food byproducts such as chitosan to develop novel food packaging films attracts the interest of industrial and institutional research centers. In this study, novel hybrid nanostructures were synthesized via the growth of zinc oxide nanorods on the surface of two nanoclays. The obtained nanostructures were incorporated with chitosan/polyvinyl alcohol composite either as nanoreinforcement or as an active agent to develop packaging films. The developed films were characterized via XRD, FTIR, mechanical, water-vapor diffusion, water sorption, and oxygen permeability measurements. Antimicrobial activity measurements were carried out against four different pathogen microorganisms. XRD indicated the formation of an intercalated nanocomposite structure for both types of nanoclays. Furthermore, improved tensile, water/oxygen barrier, and antimicrobial properties were recorded for all films compared to the pure chitosan/polyvinyl alcohol film. Overall, the results indicated that the use of the bio-based developed films led to an extension of food shelf life and could be used as novel active food packaging materials. Among them, the most promising film was the 6% wt. ZnO@halloysite.

In this study, CuMt and TiMt montmorillonites were produced via an ion-exchange process with Cu⁺ and Ti⁴⁺ ions. These nanostructured materials were characterized with X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR) measurements and added as nanoreinforcements and active agents in chitosan (CS)/poly-vinyl-alcohol (PVOH)-based packaging films. The developed films were characterized by XRD and FTIR measurements. The antimicrobial, tensile, and oxygen/water-barrier measurements for the evaluation of the packaging performance were carried out to the obtained CS/PVOH/CuMt and CS/PVOH/TiMt films. The results of this study indicated that CS/PVOH/CuMt film is a stronger intercalated nanocomposite structure compared to the CS/PVOH/TiMt film. This fact reflected higher tensile strength and water/oxygen-barrier properties. The antibacterial activity of these films was tested against four food pathogenic bacteria: Escherichia coli, Staphylococcus aureus, Salmonella enterica and Listeria monocytogenes. Results showed that in most cases, the antibacterial activity was generated by the CuMt and TiMt nanostructures. Thus, both CS/PVOH/CuMt and CS/PVOH/TiMt films are nanocomposite candidates with very good perspectives for future applications on food edible active packaging.

The concept of this study is the replacement of previous fossil-based techniques for food packaging and food shelf-life extension, with novel more green processes and materials following the spirit of circular economy and the global trend for environmentally positive fingerprints. A novel adsorption process to produce thymol-halloysite nanohybrids is presented in this work. The high dispersion of this thymol-halloysite nanostructure in chitosan biopolymer is one of the goals of this study. The incorporation of this biodegradable matrix with poly-vinyl-alcohol produced a very promising food-packaging film. Mechanical, water-oxygen barrier, antimicrobial, and antioxidant properties were measured. Transparency levels were also tested using a UV-vis instrument. Moreover, the developed films were tested in-vivo for the preservation and the extension of the shelf-life of kiwi fruits. In all cases, results indicated that the increased fraction of thymol from thyme oil significantly enhances the antimicrobial and antioxidant activity of the prepared chitosan-poly-vinyl- alcohol gel. The use of the halloysite increases the mechanical and water-oxygen barrier properties and leads to a control release process of thymol which extends the preservation and the shelf-life of kiwi fruits. Finally, the results indicated that the halloysite improves the properties of the chitosan/poly-vinyl-alcohol films, and the thymol makes them further advantageous.

Twenty-six samples of dried vine fruits from Athens and Thebes (Central Greece) market were simultaneously extracted and cleaned up by immunoaffinity columns and analysed for aflatoxin B₁ (AFB₁) and ochratoxin A (OTA). A combination of ELISA and HPLC methods was applied for the determination of AFB₁. Recovery was 97.6%, RSD 6.46%, while the limit of detection (LOD) and limit of quantification (LOQ) were 0.05 μg kg⁻¹ and 0.09 μg kg⁻¹, respectively. OTA concentrations were only estimated by ELISA. Results revealed the presence of AFB₁ in 23% of the samples (mean 1.4 μg AFB₁ kg⁻¹), but none exceeded the EU limit (2 μg AFB₁ kg⁻¹). However, OTA was detected in 100% of the samples (mean 47.2 μg OTA kg⁻¹). Six samples were found to be contaminated at high levels (median 120.6 μg OTA kg⁻¹) and 18 exceeded the EU limit (10 μg OTA kg⁻¹).

Aflatoxin B₁ (AFB₁) is considered as the most potent liver carcinogen for humans. A method for determination in sesame seeds was developed. AFB₁ was extracted by methanol-water, cleaned by immunoaffinity columns and determined by high-performance liquid chromatography with fluorescence detection. The recovery factor and the limit of detection (LOD) of AFB₁ in sesame seeds were 111.5% and 0.02 ng g⁻¹, respectively. Thirty samples of sesame products were examined for the presence of AFB₁. After analysis, 77.6% of samples were found to be contaminated. Eight samples exceeded the European Union (EU) limit (2 µg AFB₁ kg⁻¹). In 15 samples, AFB₁ was below the EU limit. Seven samples remained below the LOD. The most contaminated (14.49 ng AFB₁ g⁻¹) sample was unpeeled packaged sesame seeds. In all samples, aflatoxigenic Aspergilli fungi as well as the risk for AFB₁ presence in sesame seed was investigated.