Processing method for skim milk powder with 'clean' froth

Penn State researchers have discovered a new method of processing, by using high-pressure jets to spray milk and then quickly drying the spray, to produce skim milk powders with enhanced properties and functionality.

As concerns about ‘clean labels’ increase amongst consumers, providing recognisable ingredients on products has become a priority for food and drink manufacturers. This novel processing strategy could remove synthetic ingredients from food labels, in keeping with rising consumer demand for ‘clean’ labels.

“On the label, it would just say ‘milk proteins’ — that is something all consumers can recognise, nothing is synthetic,” said Federico Harte, Professor of Food Science at Penn State.

This method of processing could replace food emulsifying and foaming agents like carrageenan, agar, albumin, polysorbate, saccharides and lecithin, allowing consumers to recognise the ingredients in their products. Milk proteins could be used as emulsifiers or as foaming agents in food products in which a clean label is important, like ice-cream.

Researchers were able to generate a powder that can be used as a natural foaming agent. The picture shows two cappuccino coffees; the one on the right made with standard skim-milk powder and the other using powder obtained with high-pressure jet spraying and drying. Credit: Federico Harte, Penn State.

Creating skim milk powder through this method revealed notable increases in foam expansion and foam-volume stability, indicating that the skim milk powder could be a strong candidate for use in lattes. This process could be able to develop vending machine powders from just milk and coffee that can create long-lasting foam, to be used in bottled cold cappuccino coffee.

Harte published his research on high-pressure jet processing of food in the Journal of Food Processing. The study focused on a device that pressurised pasteurised, skim milk using an intensifier pump and then sprayed the milk through a diamond or sapphire nozzle.

Liquid is expelled from the nozzle as a jet of fine droplets that form an aerosol. The spray is then dried to obtain skim milk powders. Unlike liquids, powders have a wide range of applications due to their shelf-life stability and lower cost of transportation and storage.

Scaling up the process for industry is challenging, as the flow-through of the pumps is relatively low.

“We need to achieve a throughput that is attractive to industry. We are talking about a few litres per minute now, and industry needs hundreds of litres per minute. We are discussing with the manufacturers of the pumps ways to scale this up,” Harte said.

Harte has applied for a patent on foaming properties from milk protein, which is currently under revision and should be finalised by the end of the year.

Image credit: ©stock.adobe.com/au/Francesco83