Katarzyna Gębura

Grape pomace, the solid residue from winemaking, is a rich source of polyphenolic compounds with significant antioxidant properties. However, the efficient extraction of these valuable compounds remains a challenge. This study focuses on optimizing the conditions for the enzyme-assisted extraction of polyphenolic compounds from red grape pomace using cellulase, hemicellulase, and pectinase. The key variables investigated in this study were enzyme concentration, extraction time, and solid/liquid ratio. The results highlight the importance of selecting enzymes based on target compounds, as different enzymes were found to be more effective for specific phenolic fractions. Hemicellulase was most effective for phenolic acids, cellulase for catechins, and pectinase for anthocyanins. Enzyme-assisted extraction significantly increased the yield of phenolic compounds and resulted in higher total phenolic content and antioxidant activity compared to control samples treated with solid/liquid extraction without enzyme addition. These findings confirm that enzyme-assisted extraction is a promising approach for enhancing the recovery of polyphenolic compounds from grape pomace.

This paper describes studies on the preparation of an o–cresol–furfural–formaldehyde resin in the presence of an alkaline catalyst and its modification with n-butanol or 2-ethylhexanol. The novelty of this research is to obtain a furfural-based resin of the resole type and its etherification. Such resins are not described in the literature and also are not available on the market. The obtained resin based on furfural, which can be obtained from agricultural waste, had a low minimum content of free o–cresol < 1 wt.%, furfural < 0.1 wt.%, and formaldehyde < 0.1 wt.%. The resin structure was characterized by mass spectrometry (ESI-MS), FT-IR, and NMR spectroscopy, which showed the presence of hydroxymethylene groups in the resin before modification and alkyl groups derived from n-butanol and 2-ethylhexanol after modification. The etherified resins had a lower viscosity and were more flexible (DSC) than the resin before modification and they can be used as an environmentally friendly, safe, and sustainable alternative to traditional phenol–formaldehyde resins in the paint industry. They demonstrate the ability to create a protective coating with good adherence to metal substrates and an excellent balance of flexibility and hardness.

The method for determining glyphosate (NPG) and its metabolite AMPA (aminomethyl phosphonic acid) in solid food samples using UAE-SLM-HPLC–PDA technique was developed. Firstly, ultrasonic-assisted solvent extraction (UAE) and protein precipitation step were used for the analyte isolation. Then, the supernatant was evaporated to dryness and redissolved in distilled water (100 mL). The obtained solution was alkalized to pH 11 (with 1 M NaOH) and used directly as donor phase in SLM (supported liquid membrane) extraction. The SLM extraction was performed using 2 M NaCl (5 mL) as an acceptor phase. The flow rate of both phases (donor and acceptor) was set at 0.2 mL/min. The membrane extraction took 24 h but did not require any additional workload. Finally, the SLM extracts were analyzed using the HPLC technique with photo-diode array detector (PDA) and an application of pre-column derivatization with p-toluenesulfonyl chloride. Glyphosate residues were determined in food samples of walnuts, soybeans, barley and lentil samples. The LOD values obtained for the studied food were 0.002 μg g⁻¹ and 0.021 μg g⁻¹ for NPG and AMPA, respectively. Recoveries values ranged from 32% to 69% for NPG, 29% to 56% for AMPA and depended on the type of sample matrix. In the case of buckwheat and rice flour samples, the content of NPG and AMPA was below the detection level of a used analytical method.