###### Abstract  
Wine aroma represents one of the main properties that determines the consumer acceptance of the wine. It is different for each wine variety and depends on a large number of various chemical compounds. The aim of this study was to prepare red wine concentrates with enriched aroma compounds and chemical composition. For that purpose, Cabernet Sauvignon red wine variety was concentrated by reverse osmosis (RO) and nanofiltration (NF) processes under different operating conditions. Different pressures (2.5, 3.5, 4.5 and 5.5 MPa) and temperature regimes (with and without cooling) were applied on Alfa Laval LabUnit M20 equipped with six composite polyamide RO98 pH M20 or NF M20 membranes. Higher pressure increased the retention of sugars, SO\({}_{2}\), total and volatile acids and ethanol, but the temperature increment had opposite effect. Both membranes were permeable for water, ethanol, acetic acid, 4-ethylphenol and 4-ethylguaiacol and their concentration decreased after wine filtration. RO98 pHt membranes retained higher concentrations of total aroma compounds than NF membranes, but both processes, reverse osmosis and nanofiltration, resulted in retentates with different aroma profiles comparing to the initial wine. The retention of individual compounds depended on several factors (chemical structure, stability, polarity, applied processing parameters, etc.). Cabernet Sauvignon red wine; aroma compounds; reverse osmosis; nanofiltration; retention; chemical composition Article  
Aroma Profile and Chemical Composition of Reverse Osmosis and Nanofiltration Concentrates of Red Wine  
[PERSON], Ivic, Ivic, Korjar, Jukic, [PERSON], V  
environmental factors, climate, berries conditions, etc. The amount of aroma compounds that will be transferred into the grape must and wine depends on viniification techniques, especially maceration and extraction [2; 5]. Secondary aroma compounds are formed during alcoholic (converting sugar to ethanol) and lactic (converting malic to lactic acid) fermentation. Ethanol and glycerol are quantitatively dominating alcohols. Most common carboxylic acids that contribute to wine aroma are acetic acid, propanoic acid, butanoic acid, decanoic acid, etc. Acetic acid is formed in larger amounts comparing to the rest of volatile acids and contributes to the wine aroma unless it is formed in higher concentrations (above 0.9 g/L), as a result of wine spoilage [5; 6; 7]. The type and concentration of each compound depends on several factors: chemical composition of grape must, yeast strain, fermentation temperature and other viniification techniques [8]. Tertiary aroma (\"bouquet\") is formed during wine storage and aging. The final aroma depends on chemical composition of wine, pH, containers for wine aging (wood, stainless steel), maturation strategies, temperature, aeration, etc. [9]. It is visible that wine chemical composition and aroma profile depends on numerous factors that can sometimes result in a product that does not meet the standards (lower concentrations of desirable compounds or higher concentrations of compounds that negatively affect wine quality). In those cases, when wine aroma enhancement or correction is needed, membrane filtration by reverse osmosis (RO) or nanofiltration (NF) could be applied. Membrane filtration is a pressure-driven, low energy, high efficiency operation that is conducted at mild temperatures [10]. They are based on selective membrane application that split the initial feed on retentate that retains on the membrane, and permeate that yields through it [11]. Membrane properties are usually expressed through molecular weight cut-off (MWCO) that for nanofiltration membranes usually vary between 200 and 1000 Da, and for reverse osmosis they do not exceed 200 Da, depending on the manufacturer [12]. This means that RO and NF membranes permeate mostly molecules and ions with molecular weight lower than MWCO value (1 Da is usually equalized with 1 g/mol), that makes them applicable for liquid concentration.