Risk profiling of wash waters in vegetable processing industry towards possible allergen carry-over

•Industrial vegetable wash waters contain significant concentrations of protein.•Vegetable washing is a heterogeneous process.•Higher protein concentrations were found in semi-continuous than batch process.•Vegetable cutting/surface area has an effect on the protein carry-over to the water•The pH of the wash water has an impact on the protein carry-over to the water.

The carry-over of food allergens via reuse of water in the food industry deserves more attention. The lack of quantitative knowledge on this topic, hampers reliable estimations of the potential risk for the produce processing industry. Wash water samples from three vegetable processing industries were collected and significant protein concentrations were determined in the water (0-596 μg/ml). The influence of several product and process parameters on the protein carry-over from the vegetable to the wash water was studied. The type of process, batch or semi-continuous, had an impact on the protein carry-over, as well as the degree of cutting and the surface area of the vegetable. It was shown that the protein carry-over to the wash water is higher at acid pH. In the vegetable processing industry acid is often added to the wash water to prevent enzymatic browning in e.g. celeriac.