Investigating polyols to improve the efficiency of extracting anthocyans from elderberry (Sambucus nigra L.) pomace

The object of this study is the extracts from black elderberry fruit pomace obtained using various polyols (glycerol, xylitol, sorbitol), as well as their ability to extract anthocyanins, stability, persistence, and spectral characteristics. It was found that black elderberry fruit pomace is characterized by an increased content of anthocyanins (0.42±0.02 %) compared to fresh fruits (0.29±0.02 %) and juice (0.23±0.02 %), as well as a high concentration of flavonoids: rutin (1.52±0.03 %), quercetin (0.26±0.01 %), and luteolin (2.77±0.04 %). Water-ethyl and water-glycerol extracts demonstrated the highest concentration of coloring substances (57.4–58.3 g/dm³). Microstructural analysis revealed amorphous formations with a size of 50–300 nm, which contribute to the stable retention of anthocyanins. Spectral analysis confirmed the intense absorption bands of anthocyanins (1625–1725 cm^⁻1) in glycerin extracts. The high extraction capacity of glycerin solvents is due to their polarity, electrostatic interaction with anthocyanins and stabilizing properties of glycerin. Water-sorbitol and water-xylitol extracts were less stable due to their hydrophilicity and weaker ability to retain pigments. The use of glycerin as a solvent ensured maximum stability of the extracts due to the formation of amorphous structures that slow down the oxidation of anthocyanins.

The results could be used in practice in the food industry for manufacturing natural dyes, in particular in beverages, confectionery, dairy and fermented milk products. Practical implementation is possible under the following conditions: extraction temperature 65±1.5 °C, pH 3.2–3.5, concentration in a vacuum evaporator and storage at a temperature of 4±2 °C to preserve the biological activity of anthocyanins and prevent their degradation. In addition, the results of the study open up prospects for the rational use of berry pomace, which is usually subject to disposal