Innovative and Conventional Valorizations of Grape Seeds from Winery By-Products as Sustainable Source of Lipophilic Antioxidants

Abstract

<jats:p>The aim of this study was to valorize the oil recovery from red and white grape seeds (Vitis vinifera L.) that remains as by-product after the winemaking process. Oils were extracted by modern techniques, ultrasound assisted (UAE), microwave assisted (MAE) and supercritical fluid extraction (SFE), and compared to the Soxhlet extraction (SE). Firstly, SFE was optimized at different operating conditions: pressure (250–350 bar), temperature (40–60 °C), CO2 flow rate (0.2, 0.3 and 0.4 kg h−1), and particle size (315–800 µm and &gt;800 µm). The highest extraction yields were achieved by SFE at the optimal conditions: 350 bar, 60 °C, 0.4 kg h−1. Afterwards, SFE was compared to SE, UAE and MAE with respect to oil extraction yields, and analyzed for fatty acid composition and antioxidant capacity. Considering the general classification of fatty acids, it was found that samples had high content of polyunsaturated fatty acids, regardless of extraction technology. Tocopherol content was significantly influenced by all extraction methods, whereas UAE and MAE resulted in extracts richer with lipophilic antioxidants. In conclusion, modern extractions that are suited for industrial applications had better performance as compared to SE, as judging by the oil yield and quality.</jats:p>

Grape (Vitis vinifera L.) Seed Oil: A Functional Food from the Winemaking Industry

“…Solvent extraction is the more expensive method as it requires a purification final step due to the toxicity of the hexane and because it removes pigments and waxes, generating a dark and viscous product. Both hexane and pressing protocols have a high oil yield but the high working temperature is a limitation to preserving the quantity and quality of the bio-compounds obtained [ 2 , 35 , 93 ].…”

“…SFE with CO 2 is a green and low-cost alternative that produces a high-quality product compared to mechanical pressing, and though yield is lower than that of hexane-extraction, as with cold-pressing, it may improve using an enzymatically pre-treated seed [ 100 , 101 ]. SFE has been postulated to be a suitable protocol for recovering lipophilic antioxidants from wine wastes [ 93 ].…”

“…MAE uses nonionizing electromagnetic waves that are transformed to thermal energy, whereas UAE takes advantage of negative pressure after ultrasound treatment. Both techniques look for damage in cell walls to facilitate the extraction [ 93 ]. Using PLE, MAE, and UAE, lipid yields from Echium seeds were similar to those extracted with hexane [ 107 ].…”

“…In this review, we focus on Vitis vinifera grape seeds that show the best extraction oil yield using SFE compared to Soxhlet or MAE and UAE. The fatty acid composition is not remarkably affected by the extraction protocol, though antioxidant activity appears to be benefited by ultrasound technique [ 93 ]. Little was found in the literature concerning differences in grape seed oil compositions depending on the seed extract method, so further research is needed to optimize the bioactive compound production using environmentally friendly protocols [ 35 ].…”

The use of emergent technologies to extract added value compounds from grape by-products

“…Based on recent studies (Dimić et al, 2020), MAE has been referred for oil extraction from grape seeds. The authors refer to yields superior to the conventional methods (soxhlet) and advantages such as the extraction time and low temperatures that reduce the deterioration of oily compounds.…”