Polysaccharides from grape pomace: extraction and fractionation strategies and aroma modulation in Sauvignon blanc wines

Abstract

Grape pomace is a rich source of polysaccharides (PS) with potential aroma-enhancing effects in wine (Canalejo et al., 2024). The molecular weight (M_w) of PS plays a key role in determining their physicochemical and functional properties (Zhu et al., 2022). In this study, three extraction methods: acid-assisted extraction with sonication, hot water extraction and ethanol pretreatment followed by hot water extraction, were compared for recovering PS from Sauvignon blanc (SB) and Syrah (SYR) pomace. Three fractionation techniques were evaluated to separate PS into high M_w (HM) and low M_w (LM) fractions: gradient ethanol precipitation, ultrafiltration, and ion-exchange chromatography. Both hot water-based extraction methods with 80% and 40% ethanol precipitation gave higher PS yields (~10 mg/g for SB and ~5 mg/g for SYR). Gradient ethanol precipitation gave lower yields but increased PS purity and different M_w distributions. SB-derived PS showed higher proportions of low M_w PS than PS from SYR and were more suitable for separation. Ultrafiltration resulted in a low yield of LM PS (1.49%), while the yield for ion-exchange chromatography recovered LM PS was ten-fold higher (15.10%). Given these findings, two SB PS fractions were collected using ion-exchange chromatography and have been utilised in fermentation experiments. Ongoing analyses will evaluate their impact on aroma and wine stability during 12-months aging, with implications for PS application in New Zealand SB wines.

References

Canalejo, D., Martinez-Lapuente, L., Ayestarán, B., Pérez-Magariño, S., & Guadalupe, Z. (2024). Potential use of grape and wine polysaccharide extracts as fining agents to modulate the volatile composition of Viura wines. Food Chemistry, 430, 137047. https://doi.org/10.1016/j.foodchem.2023.137047

Zhu, D., Alcazar-Magana, A., Qian, Y. P., Tao, Y., & Qian, M. C. (2022). Isolation, characterization, and compositional analysis of polysaccharides from Pinot Noir wines: An exploratory study. Molecules, 27(23), 8330. https://doi.org/10.3390/molecules27238330