Aroma Profile and Chemical Composition of Reverse Osmosis and Nanofiltration Concentrates of Red Wine Cabernet Sauvignon

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 RO98pHt M20 or NF M20 membranes. Higher pressure increased the retention of sugars, SO2, 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. RO98pHt 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.).

Concentration with Nanofiltration of Red Wine Cabernet Sauvignon Produced from Conventionally and Ecologically Grown Grapes: Effect on Phenolic Compounds and Antioxidant Activity

“…In this study, the influence of four different pressures (2.5, 3.5, 4.5 and 5.5 MPa) and two temperature regimes (with and without cooling) was monitored during the nanofiltration of conventional and ecological Cabernet Sauvignon red wine. Higher pressure resulted in higher permeate flux and higher retentate temperature, which was consistent with previous studies [ 9 , 18 , 19 , 23 , 27 , 40 ]. Pressure and temperature increase resulted in a higher permeate flux and shorter NF process, but also in a higher risk of thermal degradation of retentate components, especially when cooling was not applied.…”

“…The influence of processing parameters on permeate flux, bioactive compounds retention and membrane fouling during the nanofiltration (NF) of Cabernet Sauvignon red wine was explained in more detail in our previous studies [ 9 , 18 ]. In this study, during nanofiltration of conventional and ecological wine, similar results were obtained.…”

“…However, at the same operating conditions, the permeate flux during nanofiltration is higher, the process duration time is shorter and membrane fouling is less severe than during the reverse osmosis process, which lowers the production cost [9]. The nanofiltration wine permeate contains mainly water and ethanol, but several low weight molecules can also pass through membranes, such as acetic and lactic acid, or some aroma compounds [18]. Therefore, the nanofiltration process can be used for wine or must concentration [21,22], partial dealcoholisation of wine [23,24], acetic acid removal [25,26], aroma and phenolic contents correction [9,18].…”

“…The nanofiltration wine permeate contains mainly water and ethanol, but several low weight molecules can also pass through membranes, such as acetic and lactic acid, or some aroma compounds [18]. Therefore, the nanofiltration process can be used for wine or must concentration [21,22], partial dealcoholisation of wine [23,24], acetic acid removal [25,26], aroma and phenolic contents correction [9,18]. In addition, nanofiltration can be used for the fractionation and extraction of polyphenols from grape pomace [27,28].…”

“…The permeate flux is ensured with pressure application—the smaller the membrane pore size, the higher pressure is required. Nanofiltration membranes retain small molecules and ions that create high osmotic pressure on the membrane surface, and this requires the application of high working pressure (>2.0 MPa) [ 18 ]. However, the retention of molecules on the membrane surface leads to membrane fouling, concentration polarization and permeate flux decrease that can limit the use of nanofiltration membranes [ 19 ].…”