Chip-based infant formula detection for functional proteins developed

Some manufacturers have recently started to advertise infant formulas containing elevated levels of functional proteins such as α-lactalbumin and immunoglobulin G. With regulation of these supplements expected to be enforced soon, the ability to measure these functional proteins for quality control will be imperative.

Researchers in Singapore have developed a chip-based detection system for measuring functional protein in infant formula which they say could help to control and monitor quality.

Existing techniques to detect low levels of functional proteins in milk are based on high-performance liquid chromatography (HPLC) and use expensive equipment and time-consuming methods. Pretreatment alone takes several hours.

Ruige Wu from A*STAR Singapore Institute of Manufacturing Technology and her colleagues have developed a microchip capillary-electrophoresis (CE)-based method that they say is cheaper, has a shorter assay time and eliminates the need for pretreatment.

The team fabricated a custom-made, microfluidic-chip CE device. The device separates the functional proteins from other, more abundant proteins in the formula using isoelectric focusing. In this process, the proteins move through a gel with a pH gradient and the point at which they stop on the gel depends on their charge. Since each protein has a slightly different charge, separation occurs. This takes just two minutes.

“The functional proteins are then transferred into the embedded capillary for further separation according to their mass-to-charge ratio,” explained Wu. This capillary zone electrophoresis separation step takes 18 minutes. The team then identified and measured the amount of protein present - while still on the CE column - using ultraviolet detection.

“The concentrations of functional proteins are determined from the respective absorbance values and calibration curves,” she said.

The reliability of the device was tested with infant milk formula samples spiked with known amounts of various functional proteins. “Results close to 100% recovery were obtained,” said Wu.

“Our next steps are to collaborate with industry partners in the manufacturing or quality-control testing of infant formula or similar protein-rich products.”