Comparison of k-Carrageenan, Bentonite, and Chitosan in Albariño white wine protein stabilization obtained with and without pre-fermentative skin maceration
Fernanda Cosme (1,2), Inma Arenas (2), Miguel Ribeiro (2), Luís Filipe-Ribeiro (3), Rafael Vilamarim (2), Elisa Costa (2), João Siopa (2), and Fernando M. Nunes (2,4)
(1) Biology and Environment Department, School of Life Sciences and Environment, University of Trás-os-Montes and Alto Douro, 5000-801 Vila Real, Portugal
(2) Chemistry Research Centre-Vila Real (CQ-VR), Food and Wine Chemistry Lab., University of Trás-os-Montes and Alto Douro, 5000-801 Vila Real, Portugal
(3) Sai - Segurança Alimentar Integrada, Lda, Parque Industrial de Baltar, Rua B, Lote 18, 4585-013 Baltar, Portugal (4) Chemistry Department, School of Life Sciences and Environment, University of Trás-os-Montes and Alto Douro, 5000-801 Vila Real, Portugal
Pre-fermentative skin maceration is a technique used in white wine production that aims to obtain the maximum intensity of varietal aroma, but can also increase protein concentration and consequently increase wine protein instability. Pathogenesis-related proteins (chitinases and thaumatin-like proteins) are the main determinants of white wine protein instability, producing undesirable haze, before or after bottling. This instability can cause serious economic losses. Wine protein haze formation can occur under high temperatures due to the protein self-aggregation phenomena, throughout storage or transportation, resulting in light-dispersing particles. This phenomenon needs to be prevented by removing haze forming proteins from the wine, usually by fining, before wine bottling. Bentonite fining is commonly used but can reduce sensory characteristics and produce waste. This study aims to understand the impact of alternative techniques for protein stabilization, using k-carrageenan and chitosan. The results showed that pre-fermentative skin maceration increased the levels of phenolic compounds and polysaccharides, but reduced the extraction of proteins, especially pathogenesis-related proteins, such as Vitis vinifera thaumatin-like proteins and chitinases. Although the total protein and the pathogenesis-related proteins of the Albariño wine obtained by pre-fermentative skin maceration were lower, it showed a significantly higher protein instability. k-Carrageenan reduced the content of pathogenesis-related proteins, namely the content of Vitis vinifera thaumatin-like proteins and chitinases, and consequently the protein instability in Albarino wines obtained with and without pre-fermentative skin maceration, and it was more efficient than sodium and calcium bentonites. Sodium and calcium bentonites were also able to increase the wine protein stability but only for the wine obtained without pre-fermentative skin maceration. They were less efficient in decreasing the levels of Vitis vinifera thaumatin-like proteins and chitinases in both white wines when compared to k-carrageenan. Fungal chitosan was unable to heat stabilise both wines, and pathogenesis-related proteins (Vitis vinifera thaumatin-like proteins and chitinases) levels remained unchanged. Besides the impact on the protein content and wine protein instability, the use of k-carrageenan, chitosan, sodium, and calcium bentonites also differently impacted the wine polysaccharide content. Fungal chitosan decreased the wine polysaccharide levels by 60%. Sodium and calcium bentonite also decreased the levels of wine polysaccharides although to a lower extent (16% to 59%). k-Carrageenan did not affect the polysaccharide levels. The use of k-carrageenan decreased slightly the wine filterability, but at a level that does not affect its filterability in practical terms. In conclusion, the results indicate that k-carrageenan is a suitable solution for white wine protein stabilisation, having a more desirable impact on the wine macromolecular fraction than the other fining agents, reducing the levels of the wine pathogenesis-related proteins without impacting polysaccharide composition.
Funding
This work was funded by the project “BluEnology - Desenvolvimento de um adjuvante proteico de microalgas para uso enológico”, no. NORTE-01-0247-FEDER-047005, co-financed by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020).
Acknowledgments
The authors acknowledge Fundação para a Ciência e Tecnologia (FCT-Portugal) to CQ-VR (UIDB/00616/2020 and UIDP/00616/2020), Bodegas la Caña, S.L. do Grupo Jorge Ordoñez Selections for performing the vinification process of the wines used in this study, Ceamsa, Spain, for supplying the k-carrageenan sample used in this study