Sotolon (3-hydroxy-4,5-dimethyl-2(5H)-furanone) is a naturally occurring odorant compound with a strong caramel/spice-like scent, present in many foodstuffs. Its positive contribution for the aroma of different fortified wines such as Madeira, Port and Sherry is recognized. In contrast, it is also known to be responsible for the off-flavor character of prematurely aged dry white wines. The formation mechanisms of sotolon in wine are still not well elucidated, particularly in Madeira wines, which are submitted to thermal processing during its traditional ageing. The sotolon formation in these wines has been related to sugar degradation mechanisms, particularly from fructose .
The present study focuses on the LC-MS/MS quantification results of sotolon  in model wines and serves as preliminary results in a currently ongoing project, with the aim to elucidate the main formation pathways of sotolon in fortified wines. Different combinations of fructose and amino acids in synthetic wine (base wine model – 6 g/L of tartaric acid, 18 % ethanol (v/v) and pH adjusted to 3.5) were tested and submitted to forced ageing at 70 °C for 1 month. The results showed that fructose levels as low as 1 g/L are enough to produce sotolon levels higher than the odour detection threshold preliminary found for Madeira wines . Results also showed that cysteine somehow hindered the sotolon formation in model wines.
Acknowledgements: Vanda Pereira is thankful to ARDITI (Agência Regional para o Desenvolvimento da Investigação Tecnologia e Inovação) for funding her research grant through the project M1420-09-5369-FSE-000001. This work was financed by ERDF funds and National Funds through the FCT (Fundação para a Ciência e Tecnologia) under the projects UID/CTM/50025/2013 and M1420-01-0247-FEDER-000020 (IMPACT III).
. Pereira V, Santos M, Cacho J, Marques JC. Assessment of the development of browning, antioxidant activity and volatile organic compounds in thermally processed sugar model wines. LWT. 2017, 75:719–26.
. Pereira V, Leça JM, Gaspar JM, Pereira AC, Marques JC. Rapid Determination of Sotolon in Fortified Wines Using a Miniaturized Liquid-Liquid Extraction Followed by LC-MS/MS Analysis. J Anal Methods Chem. 2018: Article ID 4393040, 7 pgs.
. Gaspar JM, Pereira V, Marques JC. Odor detection threshold (ODT) and odor rejection threshold (ORT) determination of sotolon in Madeira wine: A preliminary study. AIMS Agriculture and Food 2018, 3: 172-180.
Authors: Vanda Pereira, João M. Gaspar , Qianzhu Zhao , Ana I. Freitas , José C. Marques
Faculty of Exact Sciences and Engineering, University of Madeira, Campus Universitário da Penteada, 9020-105 Funchal, Portugal.
Department of Food Science and Engineering, Jinan University, 510632 Guangzhou, Guangdong, China
I3N, Department of Physics, University of Aveiro, 3810-193 Aveiro, Portugal
Keywords: sweet wines, thermal processing, wine ageing, wine models