Fruit juice naturally contains water %80-90, soluble solids (molecular weight is lower than 1 Kda such as sugars, organic acids, vitamins, polyphenols, aroma compounds, pigments, salts and  molecular weight is higher than 1 Kda such as polysaccharides, proteins, tannins) , non-soluble solids (cells, cell walls, fibers, crystals, starch granules, microorganisms) and thermosensitive products.

 The general production flow in the fruit juice industry starts with grinding or crushing of the fruits into an optimal and uniform size of particles and then pressing out the fruit mash. The traditional fining process consists of long retention time in tanks followed by kieselguhr filtration and requires large amounts of enzymes, gelatin and other chemicals. After clarification/fining, the fruit juice is concentrated to reduce costs for transportation and storage. The common approach to concentrate fruit juice is by using an evaporator combined with an aroma-recovery unit concentrating the apple juice from originally 11–12 Brix to over 70 Brix. The concentrated fruit juice can then be optionally pasteurized before transportation.

The general fruit juice production process including membrane processes is shown in Figure.

The clarification of fruit juice, mainly apple but also grape, pineapple and orange juice by UF has proven to be an attractive substitute for the traditional fining and filtering process from an economic and qualitative point of view since the 1970s. The UF process removes the suspended solids and other high molecular solids and the filtered juice obtains a clarity and excellent quality, which has not previously been obtainable. Thus, the UF process substitutes the fining step in the traditional process. In order to achieve high yield, high capacity and excellent quality, an enzyme treatment and proper prefiltration must be carried out before the UF system is utilized. Until now, the industrial standard is to use polymeric and ceramic tubular modules for the clarification of the juice. However, this module type is associated with low packing density and high membrane replacement costs. Furthermore, this process is commonly run in batch mode and diafiltration water has to be added in the final stage of the clarification to maximize the process yield.More recently, a new concept has been developed, which combines a high-speed mseparator with spiral-wound UF modules to overcome these limitations .  



  • Removal of non-soluble solids
  • Removal of microorganisms
  • Clarification of fruit juice
  • Concentration of fruit juice  


  • Concentration of fruit juice  




The traditional wine-making process starts with the crushing and pressing of the grapes followed by must Correction, if required. The grape juice from the pressing is centrifuged and transferred to the fermentation tanks, where the fermentation process starts under the addition of yeast. When the fermentation is completed, the yeast fraction from the wine is removed and the wine is moved into barrels for aging. After the aging, the mature wine is clarified, tartar stabilized, sterile filtered and bottled.Membrane processes can replace several of the different separation steps involved in the traditional wine production as shown in Figure 1.8. When the taste of the wine has been deteriorated or dealcoholization of the wine is desired, then these steps are taken before the sterile filtration.

The traditional fining after fermentation often involves several steps of centrifugation and kieselguhr filtration to obtain the desired quality. The use of MF/UF can reduce the number of steps by combining clarification, stabilization and sterile filtration in one continuous operation and eliminates the use of fining substances and filter material. The key to success in the clarification of wine is the membrane selection with regard to fouling behavior and pore size. Another important factor is the membrane pore diameter. A selection of critical wine compounds and their sizes is given in table.      











  • Clarification, stabilization and removal of bacteria
  • MF membranes with pore diameters between 0.20 and 0.45 mmare used for white wine and between 0.45 and0.65 mm for red wine filtration.


  • Increase sugar contents in the wine without addition of non grape components at ambient temperature and to adjust and balance the composition of the must.
  • Enrichment in tannins and organoleptic components by water reduction between 5 and 20%.
  • Rejuvenation of Wine
  • Alcohol Removal