Background The hot-water blanching of potatoes is a standard procedure in the production of chips (french-fries), and other potato-based products. The process is necessary to inactivate enzymes, gelatinise starch and reduce sugar content. The beneficiary currently processes 1.4 million tonnes of potatoes, using 0.35 million m3 of water for potato blanching, as well as 88 200 GJ (gigajoule) of energy to heat the water. Current blanching techniques neither recycle water nor recover heat from the water, emitting both water and heat to wastewater treatment plants instead. Furthermore, around 10-30% of potato solids are leached out during the process, resulting in an unwanted loss of 50 400 tonnes of raw material a year, in the form of potato waste water. Objectives The project aimed to demonstrate a closed-loop blanching technology that avoids the negative environmental impacts, and loss of raw materials, that are a characteristic of existing techniques. A pilot blanching system would be constructed and operated that would use selective de-sugaring to prevent browning, while avoiding the loss of valuable potato mass. In addition, wastewater would be processed and reused for blanching, thereby minimising water consumption. Results The CLB project developed an innovative system for the blanching of potatoes, which prevents the leaching out of nutrients that occurs in currently used blanching techniques. The concept of closed loop blanching (CLB) is based on selective leaching out of sugars during the blanching, by keeping the concentration levels of all components in the blanching water (ions enzymes, amino acids, anti oxidants, vitamins and organic acids) at a constant level, and selectively removing sugars from the water. As a consequence, leaching out of valuable raw materials is prevented and the objective of the blanching sequence (reducing sugars) is still achieved. The sugars are removed from the blanching water using a batch fermentor and the water is subsequently pumped back into the blancher. The sugar concentration difference between the potato strips and the surrounding water creates a driving force for the leaching process. The results of the project show that the CLB system can yield considerable savings in energy, water and raw materials. The environmental and economic results of the project can be summarised as follows: Significant savings of 3.6% raw material were realised. Reduction of groundwater retraction of about 240 l/tonne potatoes. Reduction of wastewater treatment requirements of 240 l/tonne potatoes. Energy reduction of 94 MJ/ tonne potatoes, which is equal to 3 m3/tonne of natural gas savings, resulting in 5.3 kg CO2 and 3.1 g NOx emission reduction per tonne processed potatoes. Savings in raw material results also in 3.6% reduced truck movements to transport the raw material to the factory (30 tonnes per truck, average travel distance of 125 km), which results in 0.121 kg CO2 and 1.5 g NOx emission reduction per tonne processed potatoes. Overall emission reduction (transport to factory plus at the factory) per tonne processed potatoes of 5.4 kg CO2 and 4.6 g NOx. Maintenance of nutritional value in the product.The technology will first be implemented at the Aviko plant in Steenderen (production volume 500 000 tonnes potatoes), and subsequently in other plants of the beneficiary (total production volume 1.2 million tonnes potatoes). Total production volume in Europe (suitable for application of the CLB technology): 10 million tonnes. An investment decision for the first production line in Steenderen is currently under preparation and is expected to be taken in August 2009. The first implementation of the CLB system on a full scale is expected to take place in 2010. This project has been selected as one of the 17 "Best" LIFE Environment projects in 2008-2009.