Abstract
Grape pomace, also known as wine pomace, is a by-product of winemaking that has traditionally been discarded. However, recent studies have highlighted its rich nutritional and bioactive potential, positioning it as a promising resource for various applications in the functional food, pharmaceutical, and cosmetic sectors. This review explores the nutrient and nutraceutical contents of grape pomace, including its high levels of polyphenols, dietary fiber, vitamins, minerals, and melatonin. The biological activities of grape pomace, such as antioxidant, anti-inflammatory, antimicrobial, and anticancer effects, are also discussed, emphasizing its potential as raw material endowed with multifunctional properties. Additionally, the valorization of grape pomace as a food supplement and for the development of cosmetics is examined, focusing on its incorporation into dietary products and skincare formulations. The growing interest in the sustainable utilization of grape pomace is underscored, highlighting its significant role in promoting human health and contributing to a circular economy.
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Nutrients and Nutraceuticals from Vitis vinifera L. Pomace: Biological Activities, Valorization, and Potential Applications
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Chapter 4
Extraction Methods for Bioactive Compounds from Vitis vinifera L. Pomace
Currently, traditional solvent extraction or green extraction methods can be used to recover bioactive ingredients from agricultural wastes, including GP. The selection of solvents and the application of heat and/or agitation are crucial factors of the traditional solvent extraction process [15]. According to Drosou et al. [81], the suitable solvents for recovering phenolic compounds from GP include water, water: ethanol (1:1), and ethanol. They are characterized by different polarities to favor the solubility of different bioactive compounds. Although the extraction yields of the extracts are strongly dependent on the nature of the solvent and the plant’s moisture content, the extraction technique affects the recovery of polyphenols too. The most widely used traditional extraction techniques are solid-liquid extraction by mechanical agitation, maceration, and Soxhlet extraction.
These methods are characterized by low equipment costs, simple flowcharts, and high yields [82]; but they require long extraction times, abundant solvent consumption, and evaporation or concentration process after extraction to obtain purer bioactive compounds. Considering these disadvantages, green extraction technologies, for example, supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), pulsed electric field (PEF), and enzyme-assisted extraction (EAE), are currently studied to extract bioactive ingredients from wine industry waste [18,83]. These technologies are more efficient due to their reduction of the extraction time, energy consumption, cost, or quantity of solvent, ensuring high quality and safe extracts. Detailed overview on the principles of extraction methods of bioactive compounds by GP were reviewed by Wang et al. [2] and Castellanos-Gallos et al. [18]. In addition, several authors have studied the recovery of polyphenols from pomace using the aforementioned extraction techniques. Casas et al. [84], Da Porto et al. [85], and Farías-Campomanes et al. [86] have successfully used SFE, and in particular supercritical carbon dioxide (SC-CO2), to recover polyphenols from GP. Caldas et al. [87] has specifically used MAE for recovering quercetin, rutin, catechin, and epicatechin as the main phenolic compounds in grape skins. In addition, anthocyanins and generally heat-sensitive bioactive compounds may be extracted by UAE, as reported by Da Porto et al. [88] and Drosou et al. [81]. Brianceau et al. [89] has demonstrated that PEF is a selective process for the recovery of anthocyanins from GP.
Recently, an innovative green solvent extraction method based on natural deep eutectic solvents (NaDESs) has garnered interest for the extraction of GP compounds, especially polyphenols [2,18,90]. NaDESs are prepared by mixing hydrogen-bond donors (HBDs) and hydrogen-bond acceptors (HBAs) at an appropriate molar ratio to make a eutectic mixture [91,92]. Jeong et al. [93] used a mixture of citric acid (HBA) and maltose (HBD) in a 4:1 M ratio as a NaDES to successfully extract anthocyanins from grape skin. The comparison of anthocyanin extraction efficiency using this NaDES with traditional methanol and ethanol extraction methods revealed that the NaDES extraction was more than twice as efficient. Panic et al. [94] investigated anthocyanin NaDES extraction from GP on a larger scale. Firstly, the research group selected the appropriate NaDES mixtures, optimizing the extraction parameters, and then investigated solvent recycling. Specifically, the anthocyanin recovery was almost 90% and the NaDES recycling yield was 77.91%. Although the utilization of renewable resources and low energy requirements has made NaDESs an appealing green alternative for extracting bioactive chemicals, their toxicity profiles differ greatly depending on their composition. Therefore, as required by regulations for food and pharmaceutical uses, toxicological studies must be conducted to determine safety for human health and environmental exposure [95].
Prata, C.; Zalambani, C.; Rossi, F.; Rossello, S.; Cerchiara, T.; Cappadone, C.; Malucelli, E. Nutrients and Nutraceuticals from Vitis vinifera L. Pomace: Biological Activities, Valorization, and Potential Applications. Nutrients 2025, 17, 583.
https://doi.org/10.3390/nu17030583
