The role of malt lipids in beer foam.

Hollemans, M., Tonies, T.R.J.M., Bisperink, C.G.J. and Ronteltap, A.D.

Abstract
Lipids extracted from malt were separated into 3 fractions, namely neutral lipids, free fatty acids and phospholipids. Beer samples to which either whole lipid extract or one of the fractions had been added were tested as follows: the dynamic and equilibrium surface tensions were measured, the spread of lipids through the beer was observed by means of a falling film apparatus, foam stability was determined by the Rudin head retention test, changes in bubble size distribution over time were observed and the drainage, foam collapse and foam height measured. It was found that malt lipid extract, neutral lipids and free fatty acids all caused a degree of deterioration in foam stability proportional to the quantity added, whereas phospholipids had no effect on foam quality. The destabilization of foam was attributed mainly to accelerated bubble coalescence.
Keywords : beer deterioration foam stability lipid malt measurement