Milk-protein residue may slip past the standard test used to detect it in processed foods, according to new research. As a result, millions of young children with milk allergy could unknowingly be exposed to milk proteins that will make them sick.
The finding, presented yesterday at a meeting of the American Chemical Society, showed that the standard enzyme-linked immunosorbent assay (ELISA) used by the food industry can’t always pick out milk proteins that have aggregated or changed shape during thermal and non-thermal food processing.
Even when altered, milk proteins still can cause allergic people to have symptoms, including wheezing, coughing, hives, vomiting, and abdominal cramps. An estimated 2% to 7.5% of infants have milk allergy, but 80% outgrow it by age 16 years.
Joseph Baumert, PhD, and his colleagues at the University of Nebraska-Lincoln examined the accuracy of ELISAs in detecting milk proteins that undergo changes in foods that are baked, boiled, fried, or heated using other techniques during processing.
ELISAs use specially designed antibodies that bind to a wide range of specific targets, from milk proteins in processed foods to viruses in human blood, and release a signal showing they’ve hit their target. Despite being sensitive, specific, and easy to use, the ability of ELISAs to detect allergens in heat-processed foods hasn’t been closely evaluated.
Baumert and his colleagues found that thermal processing can alter milk proteins sufficiently enough that they may escape detection by an ELISA. “Milk proteins can be differentially affected by thermal processing, thus limiting detection and affecting overall risk-assessment decisions,” they wrote.
Baumert said ELISA manufacturers could use the research to develop improved assays to detect milk protein residue in processed foods. “These improved tests can be adopted by the food industry, if necessary, to allow for reliable detection of milk residue regardless of the type of processing that is used,” he said in a statement.