New use of natural silk fiber as a fining agent in wines

Abstract

Undesirable compounds in wine, like OTA, biogenic amines, and pesticide residues, can negatively affect its quality and pose health risks to consumers. In addition, an excess of tannins can lead to an unpleasant rise in astringency and bitterness, which makes tannins another target of reduction. The primary method used by winemakers to lower these undesirable compounds is fining. However, some commonly used fining agents can trigger allergies or even increase the protein content in the wine, which can increase turbidity. To prevent these issues, the use of plant fibers, such as those from grape pomace, might be a viable alternative¹. Trying to find other alternatives, the objective of this work was to explore the effect of a natural fiber, the silk fibers obtained from the Bombyx mori cocoons, in the reduction of undesirable compounds and in the chromatic profile of a young red wine and an oxidazed white wine. Indeed, this natural biopolymer is not only abundant, due to the large-scale cultivation of silkworms for the textile industry, but also sustainable and can be obtained at reasonable low cost as textile by-product. A fining trial was conducted with the silk fibroin fibres, both in shredded and raw state, at the maximum concentration allowed by OIV (2 g/L) in the wines previously doped with histamine, OTA and several pesticides. After 48 h of contact, wine chromatic parameters and phenolic compound content were measured, along with the concentration of the undesirable compounds in the treated wines. The results obtained showed that the silk fibers were successful at reducing oxidized phenolic compounds in white wine and tannins in red wine, and able to significantly reduce some of the tested pesticides, histamine and OTA, affecting minimally the wine colour in red wine. For that, this fibre may be a very good alternative for obtaining safer and high quality wines.

References

[1] Jiménez-Martínez, M. D., Gil-Muñoz, R., Gómez-Plaza, E., & Bautista-Ortín, A. B. (2018). Performance of purified grape pomace as a fining agent to reduce the levels of some contaminants from wine. Food Additives & Contaminants: Part A, 35(6), 1061-1070.