Reproducing high mechanical load during industrial processing of ultra-high-temperature milk: Effect on frothing capacity

Abstract

In this study, possible reasons for an increased level of free fatty acids (FFAs) in Ultra-High Temperature (UHT) treated full fat (3.5% wt/wt) milk and its effect on the frothing properties of milk were investigated. Lipolysis of raw milk from 2 different breeds of cattle (Holstein and Jersey) was induced by mechanical stress and kinetics of lipolysis were compared. Frothing capacity and foam stability of shelf stable milk with different concentrations of FFAs were determined, with a good to medium initial foam volume for up to 4 mEquiv FFA · (100 g fat)-1 fat and poor foam stability with >2 mEquiv FFA · (100 g fat)-1. A combination of mechanical stress and initial condition of fresh raw milk was found to trigger lipolysis and potential sources of mechanical stress during milk processing were identified.