Use of lysozyme as an indicator of protein cross-contact in fresh-cut vegetables via wash waters

To evaluate risks linked to cross-contact of allergenic proteins in food production sites via carry-over, it is necessary to gain more insight in the behavior of proteins during processing. A typical case example of cross-contact is related to the re-use of wash water in the fresh-cut vegetable processing industry. In this study, the carry-over of allergenic proteins via wash water was quantified by applying an allergen-indicator, lysozyme. The adsorption of the allergen to the fresh-cut vegetables could be characterized by a Langmuir adsorption isotherm. From the adsorption characteristics, it was observed that the carry-over was significantly stronger on carrots compared to lettuce and leek. This was moreover observed from the mass balance which illustrated that the total amount of lysozyme transferred from the wash water to the fresh-cut vegetables was in average 77.4, 25.1 and 22.2% for respectively carrots, lettuce and leek. From a deterministic risk assessment, it could be concluded that allergenic proteins can be transferred via wash water to fresh-cut vegetables in the next production batch in such quantities that they pose a risk towards allergic consumers. The proposed methodology enables the food industry to validate designed preventive measures in the framework of their allergen management.

► We develop a methodology to quantify allergen carry-over in wash water. ► Allergen adsorption to vegetables is characterized by Langmuir adsorption isotherm. ► The adsorption depends strongly on the type of vegetable. ► A risk assessment shows that protein carry-over poses a risk for allergic consumers. ► The applied methodology enables food industry to evaluate cross contamination.