Alongside with new technology and process development, it is becoming more common to evaluate the environmental impact using Life Cycle Analysis, LCA. (Hospido et al., 2010). The demand for environmentally sustainable food products is increasing and it is a challenge for the food industry to reduce environmental impact along the food chain while at the same time maintaining and improving quality. In the dairy industry, chromatography is the reference technology for protein fractionation at a large scale when high purity and targeted functionality are required. Fractionation of proteins by membrane operations such as micro- and ultrafiltration has however deserved a high attention over the last years, mainly due to their acceptable investment and operating costs. The aim of this study was then to compare the environmental performances of two ways of fractionating whey proteins (reference chromatography and newly developed cascade of membrane separations) into the two following added value products: powder of α-lactalbumin with a 70% purity and powder of β-lactoglobulin with high purity (> 95%) and high foaming properties. A comparative attributional Life Cycle Analysis, LCA was carried out to evaluate the environmental impact of both processes and identify potential hot spots early in the development phase of the membrane process. The system studied includes the entire process implemented, from the entry of the whey protein concentrate into the upgrading plant to the production of the two dehydrated fractions of purified proteins. The whey comes from processes commonly performed in a classical dairy: it corresponds to the aqueous phase of milk, obtained after microfiltration of skimmed milk (Omont et al., 2010). The whey proteins are concentrated before its transportation into the upgrading plant where individual proteins will be purified and dehydrated. The system takes into account all the processing operations, the cleaning phases and the associated equipment. It excludes the facilities (buildings, lighting, etc.). Its geographic scope is France, where electricity is mainly produced by nuclear power and has a low CO2 impact. As membrane processes are high electricity consumers (Notarnicola et al. 2008, European Commission 2006, Omont et al. 2010), a sensitivity analysis has been tested between French and European electricity mixes. The inventory of the foreground system was carried out with specific data given by the industrial partners of the project. Generic data derived from the ecoinvent V2.2 data base. The impact assessment was calculated by the IMPACT 2002+ method using the Simapro 7.2 software. A water flow indicator was defined for the first level processes. The “chromatography system” and the “membrane filtration system” are described on the Table. The fractions outgoing from the chromatography are more diluted. In order to generate the same concentrated α-lactalbumin and β-lactoglobulin fractions before drying, the ultrafiltration concentrations following chromatography were resized. Results show that drying steps consume the same amount of natural gas for the two processes. The environmental load of the "chromatography separation process" is mainly attributed to the ultrafiltration operations which consume more electricity due to the resize. The Chemical Oxygen Demand contained in the non-regenerated brine and in the column cleaning wastewater also contributes to this load, because their wastewater treatment consumes electricity. It is noticeable that sodium chloride is not decomposed by the wastewater treatment plant; its discharge into the water is then not assessed by the method IMPACT 2002+, which results in an under-estimation of the environmental load of the chromatography process. The environmental impact of the "membrane filtration process" is mainly linked to the heating, the microfiltration and the ultrafiltration which consume natural gas, electricity and water due to diafiltration. As shown in Figure, the environmental load of chromatography tends to be higher than the membrane filtration. But the highest difference does not exceed 15%.The water consumption directly linked to the processes is 25% higher in case of chromatography This study shows that Life Cycle Analysis is an efficient tool to evaluate the environmental load of industrial processes provided sufficient data are available for the description of the system. It also demonstrates how LCA can be applied to support the development of new technologies for food processing in an early stage by identifying potential hot spots.