Critical points for point source pollution in the Yser catchment area (Flanders-France).

In the frame of the European TOPPS project (Train the Operator to prevent Pollution from Point Sources), 200 on farm audits and 300 tele interviews were performed in the Yser catchment area. The objective was to determine the critical points for point source pollution within the spraying process and to inform advisors, intermediaries and farmers on practical measures and achievable solutions to reduce the contamination of the surface water by Plant Protection Products (PPP) due to point source pollution. For the on farm auditing, the Aquasite tool (Arvalis-France) was used. This audit was performed on 100 farms in the Flemish Yser catchment and on 100 farms at the French side. This audit reveals the weak points in infrastructure and technology on the farm in relation to the spraying process. Next, 150 tele interviews were held in the respective catchment areas. These interviews assess the awareness and behaviour of the farmers on point source pollution. The strength of these studies is in giving a view on the real situation on the farms with respect to spraying. The critical points and risks for point source pollution were similar for both regions. Especially the filling and mixing of the sprayer, internal and external cleaning of the sprayer and the management of the waste fraction need specific training, demonstration and advice. However, there is a large difference in the risk perception of point source pollution between farmers on both sides of the border. The transgressing approach of the Yser catchment allows to make a comparison between both regions and allows to assess in which way the legislation had part in explaining the differences between the regions as the agriculture in both regions is similar. Also, the results stress the importance of trainings and sensibilisation at a regional scale.

Selection criteria for potato tubers to minimize acrylamide formation during frying.

A number of parameters linked to the selection of potato tubers were evaluated with regard to their potential to influence acrylamide formation in French fries. The formation of acrylamide, which is a potential human carcinogen, can be minimized for a big extent by the selection of an appropriate tuber. This study focused on the following selection criteria: variety as influenced by storage time and soil type, underwater weight, and tuber size. A total of 16 varieties were compared, concerning their potential for acrylamide formation. From that survey, certain varieties, such as Tebina and Quincy, could be appointed as unsuitable for frying. The differences in the potential of acrylamide formation between the varieties could mainly be explained by the reducing sugar content of the potato (R2 = 0.82, n = 96). The investigated type of soil and storage time at 8 degrees C appeared to have a minor influence on the acrylamide formation during frying. On the other hand, the tuber size of the potato did contribute in a significant manner to the acrylamide formation. Smaller tubers were more susceptible to acrylamide formation and should be avoided in the frying process. The last selection parameter, the underwater weight, appeared to be of minor importance in the acrylamide formation. On the basis of these simple selection criteria, it is possible to make a first screening of potatoes to reduce the acrylamide formation during frying.

Influence of fertilization on acrylamide formation during frying of potatoes harvested in 2003.

The quality of the potato has been found to vary, when grown under different agricultural and environmental conditions, such as the level of fertilization. Consequently these factors may influence the acrylamide formation during the preparation of French fries. These assumptions were studied on three varieties: Bintje, Ramos, and Saturna from the harvest of 2003. Decreasing N fertilization caused increases in the reducing sugar concentration from 60% up to 100% on DM for all varieties studied. Due to a high correlation between the reducing sugar content and the generation of acrylamide during frying, this resulted in a parallel increase in the acrylamide concentration of the French fries. Thus by lowering the amount of N fertilizer, an increase of 30-65% of the acrylamide generation during frying could be observed. It seems of extreme importance to find an appropriate balance between the level of N fertilizer in order to diminish acrylamide formation but on the other hand to obtain an acceptable tuber and to consider the environmental impact. All results reported should be seen in the perspective of the warm growing season of 2003.

Influence of storage practices on acrylamide formation during potato frying.

A number of parameters linked to storage of potatoes were evaluated with regard to their potential to influence the acrylamide formation in French fries. Acrylamide, which is a potential human carcinogen, is reported to be formed during the frying of potatoes as a result of the reactions between asparagine and reducing sugars. This study was conducted using three potato varieties (Bintje, Ramos, and Saturna) typically used in Belgium, The Netherlands, and the northern part of France for French fry and crisp production. Saturna, mainly used in crisp production, appeared to be the least susceptible for acrylamide formation during frying. Especially storage at low temperatures (4 degrees C) compared to storage at 8 degrees C seemed to enhance acrylamide formation due to a strong increase in reducing sugars caused by low-temperature storage. Because of the reversible nature of this physiological reaction, it was possible to achieve a significant reduction of the reducing sugars after a reconditioning of the cold-stored potatoes for 3 weeks at 15 degrees C. All changes in acrylamide concentrations could mainly be explained by the reducing sugar content of the potato (R2 = 0.84, n = 160). This means that, by ensuring a low reducing sugar content of the potato tuber, the risk for acrylamide formation will largely be reduced. Finally the use of a sprout inhibitor did not influence the composition of the potato, and thus acrylamide formation was not susceptible to this treatment.