# Impact of Chitosan-Genipin Films on Volatile Profile of Wine along Storage
###### Abstract  
Chitosan-genipin films have been proposed for preservation of white wine, maintaining their varietal key odorants and organoleptic characteristics of sulfur dioxide treated wines. Nevertheless, these wines showed aroma notes that slightly distinguish them. It is possible that during the contact of films with wine for at least 2 months, after fermentation and prior to bottling, interactions or chemical reactions are promoted. In this work, wine model solutions with volatile compounds in contact with chitosan-genipin films were performed to evaluate their evolution along time. To complement these analyses, the volatile compounds of white and red wines kept in contact with chitosan-genipin films during 2 and 8 months were also studied. The results obtained allowed us to conclude that the contact of chitosan-genipin films with both white and red wines tend to retain long carbon chain volatile compounds, such as ethyl hexanoate and octan-3-one. It also promoted the formation of Maillard reaction products, such as furfural by dehydration of pentoses and Strecker aldehydes, such as 3-methylbutanal and phenylacetaldehyde, by degradation of amino acids. This study reveals that the use of chitosan-genipin films for wine preservation is also able to promote the formation of compounds that can modulate the wines aroma, maintaining the varietal notes. chitosan; genipin; Maillard reaction; Strecker degradation; hydrophobic interaction 2021  
12 May 2021  
Accepted: 2 July 2021  
Published: 7 July 2021  
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Chitosan has legal application as clarifying agent in wine industry [1, 2, 3, 4]. However, several other different applications [5] have been proposed exploiting its properties, as complexing [6, 7], preservative [8, 9], and encapsulating agent [10, 11] in wines, as in beverages in general [12]. For wine, the chitosan from _Aspergillus niger_, was authorised by International Organisation of Vine and Wine, with a maximum concentration of 1 g/L [13], marketed as Oneobretret [8] and Bactiless [7] brands. Depending on the different purposes, such as to control the population of micro-organisms, in special _Brettanomyces_[14, 15] and for uptake of endotoxin A [6, 7], concentrations up to 5 g/L have been admitted by the European Union [16]. Chitosan is able to decrease the amount of sulphur dioxide-bound and, in this way, increase the microbial activity of sulphur dioxide in red wine, as well as its colour stability [17]. When added to pre-fermented wines, chitosan can influence their volatile composition, dependent on yeast used for fermentation, resulting in wines with different characteristics [18]. The reticulation of chitosan with genipin, forming acidic aqueous resistant chitosan-genipin (Ch-Ge) films [19], has been proposed for white wine preservation due to metal complexation properties [20], which is on the basis of the antimicrobial and anti-oxidant activities of the films [21]. This reticulation allows the use of chitosan fromdifferent origins than fungi, including seafood because the allergic response triggered by tropomyosin [22] does not occur, allowing its use as a technological adjuvant in wines that can be taken by seafood allergic patients [23]. The organoleptic characteristics of colour, taste, and aroma of white wines treated with Ch-Ge films are improved when compared to the same wines prepared using sulfur dioxide as preservative [21]. These wines were rated by an expert sensory panel with positive notes attributed to the increase in benzaldehyde and furfural possibly formed due to the reaction between amino groups and sugars in the presence of the films [21]. The improved organoleptic characteristics of these wines have also been related to the decrease in heptan-2-one and nonan-2-one, with buttery and fatty odours, and 4-ethylphenol and 4-ethylguaiacol, with clove and spicy odours [21].