Natalia Gablo

This research examined the potential for utilizing waste materials generated during the production of dishes/meals and organic waste. Specifically, it evaluated the use of orange peel (OP), spent coffee grounds (SCG), and waste cooking oil in the production of soaps. For the purposes of this study, homemade soaps were made from used food oils using the cold saponification method using sodium hydroxide. During the soap preparation, spent coffee grounds and orange peel were added to the samples in increasing concentrations of 1%, 2.5%, and 5%. The quality of the individual types of homemade soaps was evaluated on the basis of physicochemical properties such as pH, moisture, total alkalinity, total fatty matter, malondialdehyde content, fat content, foaminess, and hardness. All soaps produced using the cooking oil met the ISO quality criteria and reveal a high TFM content, low moisture content, and also very good foam stability and satisfactory foaming stability. However, no relationship was observed between the use of OP and SCG in soap production and these parameters. However, according to the ABTS test, OP and SCG significantly contributed to the antioxidant properties of the soaps, while SCG-impregnated soaps performed slightly better in this respect. Soaps with SCG also had the highest levels of flavonoids. On the other hand, the fillers used for the soap formulation reduced their hardness. All soaps showed 100% solubility in water, thus confirming the biodegradability of the product. This study demonstrated the novel potential of incorporating waste products like orange peel, spent coffee grounds, and waste cooking oil into homemade soaps, highlighting their contributions to its antioxidant properties and water solubility while ensuring high quality standards.

Coffee ranks as the second most consumed beverage globally, and its popularity is associated with the growing accumulation of spent coffee grounds (SCG), a by-product that, if not managed properly, constitutes a serious ecological problem. Analyses of SCG have repeatedly shown that they are a source of substances with antioxidant and antimicrobial properties. In this study, we assessed SCG as a substrate for the production of edible/biodegradable films. The κ-carrageenan was utilized as a base polymer and the emulsified SCG oil as a filler. The oil pressed from a blend of Robusta and Arabica coffee had the best quality and the highest antioxidant properties; therefore, it was used for film production. The film-forming solution was prepared by dissolving κ-carrageenan in distilled water at 50 °C, adding the emulsified SCG oil, and homogenizing. This solution was cast onto Petri dishes and dried at room temperature. Chemical characterization showed that SCG increased the level of polyphenols in the films and the antioxidant properties, according to the CUPRAC assay (CC1 23.90 ± 1.23 µmol/g). SCG performed as a good plasticizer for κ-carrageenan and enhanced the elongation at the break of the films, compared with the control samples. The solubility of all SCG films reached 100%, indicating their biodegradability and edibility. Our results support the application of SCG as an active and easily accessible compound for the food packaging industry.

The recognition and growing consumption of cold-pressed rapeseed oil (CPRO) is due to by its unique, health-promoting properties; it is a rich source of omega-3 fatty acids and antioxidants. Nevertheless, the high content of unsaturated fatty acids and plant tissue particles makes CPRO more susceptible to oxidation. These pro-oxidant plant particles can be eliminated via centrifugation, thus improving the quality and stability of CPRO. Therefore, we aimed to determine whether the clarification of CPRO via centrifugation affects its quality parameters, pigment and phenolic profile, and antioxidant properties. These characteristics were analyzed and compared between centrifuged CPRO and CPRO clarified via natural decantation. Changes were monitored for 6 months of oil storage at 22 °C. Based on the results, no changes in the oxidation profile were found between centrifuged CPRO and decantated CPRO. When the storage is longer than 1 month, centrifugation is more beneficial with regard to delaying hydrolytic deterioration, while decantation provides slightly better pigment and polyphenol profiles. We did not observe that centrifugation improved the oil’s antioxidant properties. Further research should be continued to establish the effects of centrifugation on CPRO quality, including parameters such as rapeseed quality, maturity degree, varieties, and stricter storage conditions.