Membrane processes have become major tools in food processing for more than 25 years. The food industry represents a significant part of the turnover of the membrane manufacturing industry worldwide. The main applications of membrane operations are in the dairy industry (whey protein concentration, milk protein standardization, etc.) far before beverages (wine, beer, fruit juices, etc.) and egg products. Among the very numerous applications on an industrial scale a few striking particular separations which represent the last advances in food processing are reported. Clarification of fruit, vegetable and sugar juices by microfiltration or ultrafiltration allows the flow sheets to be simplified or the processes made cleaner and the final product quality improved. Enzymatic hydrolysis combined to selective ultrafiltration can produce beverages from vegetable proteins. In the beer industry, recovery of maturation and fermentation tank bottoms is already applied at industrial scale. During the last decade significant progress has been performed with microfiltration membrane in rough beer clarification which is the most important challenge of this technology. In the wine industry the cascade cross-flow microfiltration (0.2 ~m pore diameter) - electrodialysis allows limpidity, microbiological and tartaric stability to be ensured. In the milk and dairy industry, recent developments of cross-flow microfiltration (1.4 p.m) for the production of drinking milk and cheese milk are reported. Cross-flow microfiltration (0.1 ~m) makes it possible to achieve the separation of skim milk micellar casein and soluble proteins. Both streams are given high added value in cheese making (retentate) and through fractionation and isolation of soluble proteins (13-1actoglobuline; cx-lactalbumine) (permeate). At last, a large field of applications is emerging for the treatment of individual process streams at source for water and technical fluids re-use and end of pipe treatment of combined effluent streams, while reducing sludge production and improving the final purified water quality.
Membrane processes have become major tools in food processing for more than 25 years. The food industry represents 20 to 30 % of the current $ 250 million turnover of the membrane manufacturing industry worldwide. The growth of the market is around 7.5 % per year. Several hundreds of thousand square meters of membrane (Ultrafiitration, UF: 400,000; Nanofiitration, NF: 300,000; Reverse osmosis, RO: 100,000; Microfiltration, MF: 50,000)are currently operating. The main applications of membranes are in the dairy industry (close to 40 %, of which over l0 % for milk protein standardization), far before beverages (wine, beer, fruit juices, etc.) and egg products (2 %). Other fields are emerging: fruit and vegetable juices and concentrates, waste streams, coproducts (recovery and recycling of blood plasma in abattoirs) and technical fluids (brines, cleaning-in-place solutions).
Two extensive and informative reviews about the insertion of membrane operations in food processing have been recently published. Cheryan ~ reports about the applications of ultrafiltration and microfiltration in diverse fields of food processing such as the dairy industry, waste waters (oily waste waters, caustic and acid recovery, brine recovery, etc.), sugar refining, soybean and other vegetable proteins, vegetable oils, corn and other grains, animal products, biotechnology applications, fruit juice and extracts, alcoholic beverages (wine, beer). Daufin et al. 2 give detailed information about the use of membrane operations (cross-flow filtration, MF - UF - NF - RO; electrodialysis, ED; pervaporation, PV, etc.) in the dairy industry (milk, whey, p