Chitosan as an antioxidant alternative to sulphites in oenology: EPR investigation of inhibitory mechanisms

Abstract

The efficacy against oxidative degradation in model and sulphite-free white wines of two commercial, insoluble chitosans (one being approved for winemaking) were investigated by electron paramagnetic resonance (EPR). Both compounds at various doses significantly inhibited the formation of -(4-pyridyl-1-oxide)-N-t-butylnitrone (4-POBN)-1hydroxyethyl adducts under normal wine storage conditions. Pre-incubation with 2 g/L chitosan followed by filtration had a better effect than adding 50 mg/L sulphur dioxide to the experimental Chardonnay wine on the release of 4-POBN adducts after 6 days of incubation with 100 M iron(II). In a relevant photooxidative system acetaldehyde formation was significantly reduced after 6 days of incubation. Parallel EPR tests were performed to assess the importance of metal chelation (iron and copper) versus direct scavenging of hydroxyl radicals on the effect of chitosan. The present data support the potentiality of using biocompatible chitosan as a healthier complement and/or alternative to sulphur dioxide against white wine oxidative spoilage.

Physico-Chemical Features of Sangiovese Wine as Affected by a Post-Fermentative Treatment with Chitosan

“…To evaluate the effect of chitosan on the color of red wines, in a first approach the optical density at 420, 520 and 620 nm was measured ( Table 1). As also already described elsewhere [23,26], chitosan addition resulted in a reduction of the absorbance related to yellow nuances (420 nm) regardless the physical form of addition (dissolved or solid). Lower values of optical densities at 520 and 620 nm on KT and KTS were also recorded.…”

Effects of the pre‐fermentative addition of chitosan on the nitrogenous fraction and the secondary fermentation products of SO2‐free red wines

“…showed the efficacy of chitosan to improve the sensory profile of red wines contaminated with volatile phenols, and reported that chitosan reduces negative and bitter phenolic sensory attributes and increases positive fruit and floral notes. More recently, Castro ‐ Marín et al 13 . reported the potential of using biocompatible chitosan as a healthier supplement and/or alternative to SO 2 against the oxidative deterioration of white wine due to its Fe (II) chelating activity, which inhibits the formation of 1‐hydroxyethyl radicals.…”

Inhibitory effect of fungoid chitosan in the generation of aldehydes relevant to photooxidative decay in a sulphite-free white wine

“…(not represented in Fig.1 for clarity), or binding acetaldehyde and glyoxylic acid (Grant-Preece et al, 2017a, b), but would stop after complete consumption of sulphites, as already observed for the inhibition of 1-HER formation (Castro Marin et al, 2019). Figure 4B shows the oxidative browning in experimental white wine which, at opening, contained 2.9 mg/L total catechins and 1.2 mg/L total epicatechins.…”