Antimicrobial potential of oregano essential oil vehiculated in Pickering cellulose nanofibers-stabilized emulsions.

Essential oils show several biological properties, such as antimicrobial activity, but have limitations regarding their availability and stability. To maximize their antimicrobial effect and protection against environmental conditions, Pickering-type emulsions were used to vehiculate oregano essential oil (OEO) using cellulose nanofibers (CNF) as emulsion stabilizer. Enzymatic hydrolysis was used to produce CNF from a food industry waste (cassava peel), obtaining an environmentally sustainable emulsion stabilizer. It was evaluated how the different properties of the nanofibers affected the stability of the emulsions. Furthermore, the composition of the dispersed phase was varied (different ratios of OEO and sunflower oil-SO) in view of the target application in biodegradable active coatings. Even at very low concentration (0.01 % w/w), CNF was able to form kinetically stable emulsions with small droplet sizes using oil mixtures (OEO + SO). The stabilization mechanism was not purely Pickering, as there was a reduction in interfacial tension. Excellent antimicrobial activity was observed against bacteria and the fungus Alternaria alternata, demonstrating the ability to apply these emulsions in active systems such as coatings and films. An improvement in the stability of emulsions was observed when using a mixture of oils, which is extremely advantageous considering costs and stability to heat treatments, since the desired antimicrobial activity is maintained for the final application.

Effect of Gliding Arc Plasma Jet on the Mycobiota and Deoxynivalenol Levels in Naturally Contaminated Barley Grains.

Fusarium graminearum and Fusarium meridionale are primary contaminants of barley, capable of producing several mycotoxins, mainly type B trichothecenes and zearalenone. Cold plasma decontamination has been gaining prominence, seeking to control the fungal and mycotoxin contamination of food and feed and to improve product quality. To reach this objective, the present study was divided into two parts. In the first part, F. meridionale and F. graminearum strains were exposed to gliding arc plasma jet (GAPJ). Cell viability tests showed the inactivation of F. meridionale after 15-min treatment, whereas F. graminearum showed to be resistant. In the second part, barley grains were treated by GAPJ for 10, 20, and 30 min, demonstrating a reduction of about 2 log CFU/g of the barley's mycobiota, composed of yeasts, strains belonging to the F. graminearum species complex, Alternaria, and Aspergillus. A decrease in DON levels (up to 89%) was observed after exposure for 20 min. However, an increase in the toxin Deoxynivalenol-3-glucoside (D3G) was observed in barley grains, indicating a conversion of DON to D3G.

Extraction optimization, biological activities, and application in O/W emulsion of deep eutectic solvents-based phenolic extracts from olive pomace.

This study evaluated the phenolic compound extraction from olive pomace with deep eutectic solvents (DES) prepared with choline chloride ([Ch]Cl) and four (poly-)carboxylic acids. Temperature, water addition in the solvent, and solid-liquid ratio were evaluate in total phenolic content and antioxidant activity of extracts obtained with DES and ethanol, as control. Moreover, the antimicrobial activities of solvents and extracts were evaluated. Oil-in-water emulsion with DES extract was prepared, characterized and its oxidative stability analyzed. The extract with the highest total phenolic content was obtained with [Ch]Cl:malonic acid. Under optimal conditions, DES extracted 9 % more total phenolic content than ethanol. DES extract showed superior antibacterial activity to the ethanolic extract, and its presence in oil-in-water emulsion increased the induction time in 10-fold when compared to the one prepared with water. These results reinforce that DES are a potential solvent for phenolic compound extraction from olive pomace with antibacterial and technological benefits.