Assessing the efficiency of essential oil and active compounds/poly (lactic acid) microcapsules against common foodborne pathogens.

Essential oils' active compounds present great potential as a bactericidal agent in active packaging. The encapsulation in polymeric walls promotes their protection against external agents besides allowing controlled release. This work produced PLA capsules with three different active compounds, Cinnamomum cassia essential oil (CEO), eugenol (EEO), and linalool (LEO), by emulsion solvent evaporation method. Characterizations included SEM, Zeta potential, FTIR, TGA, and bactericidal activity against E. coli, S. aureus, L. monocytogenes, and Salmonella. The active compounds showed microbiological activity against all pathogens. CEO capsules showed superior colloidal stability. The active compounds' presence in all capsules was confirmed by FTIR analysis, with possible physical interaction between CEO, EEO, and the polymeric matrix, while LEO had a possible chemical interaction with PLA. TGA analysis showed a plasticizing effect of active compounds, and the loading efficiency was 39.7%, 50.7%, and 22.3% for CEO-PLA, EEO-PLA, and LEO-PLA, respectively. The capsules presented two release stages, sustaining activity against pathogens for up to 28 days, indicating a satisfactory internal morphology. This study presented methodology for encapsulation of antimicrobial compounds that can be suitable for active food packaging. CEO-PLA capsules regarding stability and antibacterial activity achieved the best results.

The influence of PBAT content in the nanocapsules preparation and its effect in essential oils release.

Nanoencapsulation provides new alternatives for the food industry, enabling a controlled and slow release of active antimicrobial agents, such as essential oils (EO). Poly (butylene adipate-co-terephthalate) (PBAT) nanocapsules loaded with linalool EO were prepared using an extrusion method with 1, 3, and 5% w/v (PBAT to chloroform). Nanocapsules' sizes ranged from 100 to 250 nm and were spherical. The release profile was studied using an ethanoic medium over 24 h, and according to the Korsmeyer-Peppas model, a Fick diffusion mechanism was involved. FT-IR and thermogravimetric analyses confirmed EO encapsulation with an encapsulation efficiency of 55%, 71%, and 74% for 1, 3, and 5%, respectively. The results indicated that encapsulation depended on organic phase concentration, with higher PBAT contents achieving better results. The resulting nanocapsules had antimicrobial activity against E. coli, which could be extended to develop active packaging systems.

Pinus residue/pectin-based composite hydrogels for the immobilization of ß-D-galactosidase.

The aim of this work was to synthesize pinus residue/pectin-based composite hydrogels for the immobilization of ß-D-galactosidase. These hydrogels were synthesized via chemical crosslinking, and characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, thermal analysis, mechanical assays, X-ray diffraction, and swelling kinetics. The water absorption mechanism in the hydrogel networks occurs by non-Fickian transport. The ß-D-galactosidase immobilization capacities of the hydrogels containing 0, 5 and 10% of pinus residue were respectively 242.08 ± 0.36, 181.27 ± 0.50 and 182.71 ± 0.36 mg enzyme per g dried hydrogel, at pH 4.0 and after 600 min. These values were 182.99 ± 0.41, 219.99 ± 0.47 and 218.56 ± 0.39 mg g-1, respectively, at pH 5.6. Pectin-based hydrogels demonstrated to be excellent solid supports for the immobilization of enzymes. ß-D-Galactosidase immobilized in pectin-based hydrogels could be applied in the hydrolysis of lactose contained in either dairy foods or lactose-intolerant individuals.

A study of the controlled degradation of polypropylene containing pro-oxidant agents.

Intentional degradation by pro-oxidant agents, many of which are metal-based, can result in uncertainty as to the time of biodegradation. Polyacetal (POM) is a thermoplastic polymer commercially classified as an engineering polymer and contains carbon, hydrogen and oxygen. The depolymerization of POM during processing can enhance thermal decomposition. The aim of this study was to investigate the controlled degradation of polypropylene induced by the degradation of POM or d2w®. Mixtures of polypropylene containing different concentrations of POM or d2w® were prepared by extrusion. The properties of the mixtures (blends) were evaluated based on the melt index (MFI), tensile properties, Fourier transform infrared spectroscopy (FTIR), Time inductive oxidation (OIT) and Thermogravimetric analysis (TGA). The two additives (POM and d2w®) enhanced the oxidative thermal degradation of polypropylene and the degradation of the polypropylene/POM mixture could be controlled by altering the POM concentration.