# Different SO\({}_{2}\) Doses and the Impact on Amino Acid and Volatile Profiles of White Wines
94, 7006-554 Evora, Portugal; [EMAIL_ADDRESS]  
[PERSON]  
3 MED--Mediterranean Institute for Agriculture, Environment and Development & CHANGE--Global Change and Sustainability Institute, Departamento de Fitocenia, Escola de Ciencias e Tecnologia, Universidade de Evora, Polo da Mitra, Ap. 94, 7006-554 Evora, Portugal; [EMAIL_ADDRESS]  
[PERSON]  
1 LAQV-REQUIMTE, Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal; [EMAIL_ADDRESS]  
[PERSON]  
2 MED--Mediterranean Institute for Agriculture, Environment and Development & CHANGE--Global Change and Sustainability Institute, Departamento de Fitocenia, Escola de Ciencias e Tecnologia, Universidade de Evora, Polo da Mitra, Ap. 94, 7006-554 Evora, Portugal; nmartins@uevora. is now emerging [7; 8]. In addition to environmental concerns, the excessive exposure of consumers to sulfites through food products increases the report of allergic episodes, and, therefore, overexposure to sulfites increases public health concerns [9]. The European Union, in order to meet health as well as environmental concerns, introduced sulfites in the list of substances and/or products causing allergies or intolerances whenever concentrations are present in values higher than 10 mg/kg or 10 mg/L regarding the total SO\({}_{2}\) content [10]. Currently, there is already an indication to label food products when SO\({}_{2}\) contents are equal to or greater than 10 mg/kg or 10 mg/L and concomitantly to reduce or replace this additive [11; 12]. Replacements for SO\({}_{2}\) are being pursued while maintaining the quality of the final product. However, it appears to be difficult to find a compound as versatile as SO\({}_{2}\)[13; 14; 15]. SO\({}_{2}\), among other known characteristics, acts in the winemaking process as an antioxidant and antiseptic [16]. SO\({}_{2}\) at wine pH in an acid-base equilibrium system is present in three forms: molecular SO\({}_{2}\), bisulfite (HSO\({}_{3}\)\({}^{-}\)), and sulfite ions (SO\({}_{3}\)\({}^{2-}\)) [17; 18]. The way these three forms act and impact the winemaking process is known and has been extensively described [13; 19; 20; 21; 22]. The application of different doses of SO\({}_{2}\) on the alcoholic fermentation step of the winemaking process, the simultaneous impact on the yeast nitrogen metabolism, and the role of SO\({}_{2}\) as a protective agent for yeast against stress conditions during fermentation, such as the increasing presence of ethanol levels, have also been reported [23; 24]. Aging and storage conditions influence the amino acid (AA) content of wines. Indeed, keeping wines over lees tends to increase nitrogenated substances, namely AAs, since yeast autolysis occurs and intracellular enzymes slowly hydrolyze yeasts cells, releasing AAs into the wine medium [25; 26]. Additionally, when wines undergo cold stabilization, aiming to achieve tartaric stabilization, followed by filtration before bottling, the AA content is reduced [20]. During storage, the VOC profile of wine also changes, affecting wine aroma and quality [27]. SO\({}_{2}\) has an important role in preventing microbiological spoilage and oxidation, which both negatively affect the VOC profile and, hence, the organoleptic characteristics of the final product [28]. The main aim of this work was to understand the influence of different doses of SO\({}_{2}\) (added after alcoholic fermentation) on VOCs of wine over time, as well as the AA content of wines after 3 months over fine lees. The goal was to evaluate the behavior of wines impacted by SO\({}_{2}\) doses in order to be able to safely decrease their addition without compromising quality. Headspace solid-phase microextraction gas chromatography/mass spectrometry (HS-SPME-GC/MS) was used to identify and semi-quantify VOCs. High-performance liquid chromatography-diode array detection (HPLC-DAD) was used for AA detection and quantification.