The production of bioactive peptides from egg white proteins (EWPs) and their separation are emerging areas with many new applications. The objective of this study was to compare antioxidant activity of three distinct EWP hydrolysates and their peptide fractions prepared by membrane ultrafiltration using membranes with 30, 10 and 1 kDa molecular weight cutoff. The hydrolysates were obtained by thermal and ultrasound pretreated EWPs hydrolyzed with a bacterial protease, Alcalase. It appeared that the pretreatment significantly affected peptide profiles and antioxidant activity of the hydrolysates measured by ABTS, DPPH and FRAP methods. The hydrolysate prepared using alcalase and ultrasound pretreatment at 40 kHz-15 min has shown to be the most effective in scavenging both DPPH and ABTS radicals (28.10±1.38 and 79.44±2.31%, respectively). It has been noticed that this hydrolysate had a nutritionally more adequate peptide profile than the other hydrolysates with a much lower amount of peptides <1 kDa (11.19±0.53%) and the greatest content of the peptide fraction in the molecular weight (MW) range of 1-10 kDa (28.80±0.07%). This peptide fraction has shown the highest DPPH and ABTS antioxidant activity compared to all other fractions having a potential to be used as a functional food ingredient.

The problem of environmental pollution becomes more worrisome day by day, primarily due to the large amounts of wastewater contaminated with various harmful organic compounds, discharged untreated or partially clean into the environment. Feasibility of use of horseradish peroxidase (Amoracia rusticana) in the synthetic dyes decolorization was approved by many researchers. Among a number of supports used for the immobilization, it was found that natural clay, kaolin, has excellent features which are a precondition for obtaining biocatalysts with the excellent performances. For this reason, a horseradish peroxidase was immobilized onto kaolin using glutaraldehyde as a cross-linking agent. Obtained biocatalyst was applied in the decolorization of anthraquinone dye C.I. acid violet 109. Under determined optimal conditions (pH 4.0, hydrogen peroxide concentration 0.6 mM, dye concentration 30 mg L-1 , temperature 24 °C) around 76% of dye decolorization was achieved. Reusability study showed that resulting biocatalyst was possible to apply four times in the desired reaction with relatively high decolorization percentage.

Finding a sustainable and ecofriendly methods for recalcitrant synthetic dyes removal is a researchers` major challenge. A carrier-free technique for commercial HRP immobilization is a focus of the present study. The immobilized biocatalyst, HRP-CLEAs with 580 U g-1 of the activity was obtained under the following immobilization conditions: precipitation reagent 80% ammonium sulphate, cross-linking reagent 1% of glutaraldehyde and protein-fedder, bovine serum albumin (BSA) concentration 5 mg ml-1. The obtained HRP-CLEAs showed great affinity towards model anthraquinone dye, C. I. Acid Violet 109. 88.4% of the dye was oxidized under the reaction conditions: pH 4, dye concentration 40 mg l-1 , H 2 O 2 concentration 1 mM and 0.1 U of HRP-CLEAs. The possibility of the immobilized biocatalyst application in five and eight oxidation cycles of the dye and pyrogallol (retained activity ~ 80%), respectively, indicates that HRP-CLEAs is an efficient and environmentally friendly biocatalyst with great potential in aromatic compounds removal from wastewater. This paper is a continuation of our earlier research related to HRP from horseradish extract immobilization in the form of CLEAs and the application in the wastewater colored with a synthetic anthraquinone dye treatment.

Article Highlights • Nicosulfuron was subjected to different Fenton reactions at the pH of a nicosulfuron aqueous solution • The Fenton reaction was much faster and more efficient than the Fenton-like reaction • The photo-Fenton reaction proceeded much faster and more efficient than the Fenton reaction • The MW-Fenton reaction proceeded with increased efficiency in comparison to the Fenton reaction • The toxicity tests showed the decrease in toxicity after the treatment Abstract Nicosulfuron, a sulfonylurea herbicide, was subjected to different Fenton reactions at pH of a nicosulfuron aqueous solution (pH 5). Usually, the optimal pH for the Fenton reaction is between 3 and 4, but the addition of acids is not environmentally acceptable. This is the reason why the reactions were performed at a higher pH value than usual. So, classical Fenton and Fenton-like reactions were applied as well as photo-Fenton and photo-Fenton-like reactions. In addition, microwave Fenton and Fenton-like reactions were used in nicosulfuron degradation. Influences of Fe 2+ and Fe 3+ concentrations, as well as hydrogen peroxide concentrations, were studied. The Fenton reaction was much faster and more efficient than the Fenton-like reaction, while the photo-Fenton reaction proceeded much faster and more efficiently than the Fenton reaction. The microwave-Fenton and microwave-Fenton-like reactions proceeded with increased efficiency in comparison to the Fenton and Fenton-like reactions. The phytotoxicity and acute toxicity of the reaction products of nicosulfuron oxidation by the photo-Fenton reaction were analyzed. The toxicity testing of nicosulfuron treatment by photo-Fenton process showed a decrease in phytotoxicity, while the acute toxicity tests showed that the samples after treatment had lower toxicity.