Exploring the inhibitor effect of different commercial chitosan-based preparations on malolactic fermentation in rosé wine

Abstract

Chitosan is a natural polymer of β-D-linked N-acetyl-D-glucosamine units (1,2), that has only recently been approved by OIV for its use in winemaking to help with microbial control, metal chelation, clarification, and reducing contaminants¹. Beyond wine, it has also been shown to exhibit other beneficial properties, such as antioxidant and antiradical effects, in various foods. However, the full extent of its actions in must and wine has yet to be thoroughly explored. For microbial control, sulphurous is usually used in wine industry, but this compound has some risks and inconveniences that make it necessary to look for alternatives to its use, even though it is cheap and very practical. The main issue with sulphites is that they are allergenic compounds that can cause severe reactions in sensitive populations or in high concentrations they modify the sensory properties of the wine².

In this study, we aimed to test four commercial chitosan-based preparations to inhibit malolactic fermentation in a rosé wine produced in our experimental winery and compared them to sulphurous treatment. Microbiological analysis of lactic and acetic bacteria, together with the determination of malic, lactic and acetic acid concentrations were carried out in the wine for 45 days. Furthermore, the composition of the chitosan samples was analysed by mass spectrometry. The results showed that only two of the quitosan treatments were able to effectively inhibit the malolactic fermentation, while the other treatments, including the sulphurous treatment, were only capable of delaying it. Among the chitosan treatments that inhibit the fermentation, one, which managed to reduce the CFU/mL to zero in only seven days, was a preparation that also contained small amounts of fumaric acid in the formulation, while the other treatment, where the formulation was composed only of a yeast extract and chitosan reduced the CFU/mL more slowly until after about 30 days reached zero. These results allow us to correlate the composition of the different chitosan preparations with their effectiveness, as well as to show that certain chitosan combinations can inhibit malolactic fermentation more effectively than a sulphurous treatment.

References

[1] Castro Marín, A., Colangelo, D., Lambri, M., Riponi, C., & Chinnici, F. (2021). Relevance and perspectives of the use of chitosan in winemaking: A review. Critical Reviews in Food Science and Nutrition, 61(20), 3450-3464.

[2] Vally, H., Misso, N. L., & Madan, V. (2009). Clinical effects of sulphite additives. Clinical & Experimental Allergy, 39(11), 1643-1651.