A food scientist in the US claims to have come up with a solution to the murky liquid that floats at the top after tearing off the foil lid from a cup of yoghurt.
New manufacturing techniques developed by John Lucey at the University of Wisconsin-Madison could keep this watery substance - called surface whey - beneath the surface without adding extra ingredients.
The whey separates from the yogurt's gel structure during the standard manufacturing process. Although it does not affect quality, consumers often take it as a sign that they should throw away the yoghurt. To stop separation, most yoghurt makers add stabilisers, such as pectin. But, as Lucey notes, doing so increases cost and reduces consumers' perceptions of yoghurt as a health food.
He found that simply lowering the incubation temperature creates fewer defects without affecting production time. Lucey and graduate student Wonjae Lee are now developing tests that allow yoghurt makers to determine how their manufacturing and fermentation processes affect the formation of surface whey.