Silicon carbide (SiC) membranes in œnology: a laboratory-scale study

Abstract

Unfiltered wine is a turbid medium that is not generally accepted by the consumer. Therefore, one or several filtration steps are required before bottling. Silicon carbide (SiC) membranes desirable parameters (porosity, tortuosity fluxes) allow filtering several different types of loaded matrices like wine or residue sediment. An in-depth filtration study was carried out on white and red wines to evaluate membrane efficiency and to optimise their cleaning procedure. Retention rates were studied as a function of wine type, filtration mode, and volumetric concentration factor. Compared to ceramic membranes, SiC membrane permeate fluxes are higher, up to a factor of 10 for red wine. For white wines, equivalent permeate fluxes could be obtained with dead-end filtration. Moreover, SiC membranes appear to be effective in obtaining a clear and brilliant wine and do not modify the concentration of the compounds of interest in wine. Finally, an optimised cleaning protocol has been identified and shown to restore a sufficient permeability to the SiC membranes.

Silicon carbide (SiC) membranes in œnology

“…It should be noted that the use of SiC membranes brings other advantages such as (i) limiting the fouling of the membranes because the channels have a large diameter, (ii) during the filtration of very fouling products and even if the regenerations did not pose any problem, "stronger" cleanings with more extreme pH could be performed, (iii) limiting the immobilization of volume due to the long settling time. These filtration tests on several matrices on an industrial scale are in agreement with the results obtained in the laboratory [36].…”

“…On wines (DWW1; SRW; RWB) that were filtered later, this problem was solved and turbidity and CI returned to values in line with the objectives. These values confirm the results obtained in experiments carried out on Crystar FT250 membranes at the lab scale [36] and show that these membranes can be used prior to bottling, achieving the turbidity and CI targets set. The chromatic characteristics of the wines presented (Table 7) show that all ΔE are between 0 and 1 (except for RWB).…”

“…4 shows that the permeability of the SiC membranes drops very quickly at the beginning of filtration (up to 87% for a VCF of 1.60 in the case of SRW -"difficult") and then tends towards stability until the end of filtration. These observations, as in the laboratory scale tests [36], reflect a rapid and significant fouling of the membranes at the beginning of filtration. However, if the trend of the curves is similar, the membranes do not clog up as quickly and strongly for the three types of wines filtered.…”

“…The values for the hollow fibers are imposed and used in the winery and those for the SiC membranes were determined from laboratory scale experiments [36]. It is important to note that while the maximum…”

“…The microstructure of the SiC membranes was analyzed (porosity, granulometry, tortuosity, etc.) and laboratory scale tests confirmed the potential of these membranes [36]. In order to study the impact of SiC membranes on wine, classical physicochemical analyses are carried out on wines before and after filtration (tannins, anthocyanins, polyphenols, chromatic characteristics, polysaccharides and mannoproteins).…”