Effects of High Pressure–Low Temperature treatment on freezing behavior, sensorial properties and air cell distribution in sugar rich dairy based frozen food foam and emulsions

The basic principles of High Pressure Low Temperature treatment (HPLT) of foods have been extensively explored in several studies over the last decade. Research activities in this field mostly focused on the inactivation of microorganisms, textural damage in plant and animal tissue and mechanisms behind nucleation and ice formation. Of central concern in the present study is the effect of High Pressure Low Temperature treatment on the properties of dairy based, emulsified frozen food foam and the equivalent non aerated liquid system. Special emphasis was put on the freezing behavior under pressure, sensorial properties, the air cell distribution and ice crystal size and distribution. A phase diagram was modeled on the base of atmospheric pressure DSC data and freezing and melting points determined at atmospheric and high pressure conditions.High Pressure Shift Freezing (HPSF) from metastable liquid state at max. pressure of 360 MPa and − 25 °C and pressure induced solid–solid phase transition (ice I–ice III–ice I) were applied. Liquid non aerated emulsion was HPLT treated in the presence of air to investigate the potential of aeration upon pressure release due to expansion of supercritical and dissolved gas. The latter treatment did not result in the formation of air cells in the partially frozen matrix. In HPLT experiments that started with liquid foam, the volume fraction of the incorporated air after treatment was about 78% of the reference value before treatment and the average ice crystal size was reduced from 40 μm to 34 μm. When frozen foam was HPLT treated, ice I to ice III phase transition occurred and a massive volume reduction of the gas fraction was observed. All samples showed an increase in smoothness and mouth coating in technical tasting after HPLT treatments.Industrial relevanceHigh Pressure Low Temperature processes (HPLT) offer a wider range of different effects that can be induced by different treatments. In the past, scientific work in this field was predominantly focused on the inactivation of microorganisms, textural damage in plant and animal tissue and mechanisms behind nucleation and ice formation. Of central concern in the present study is the effect of High Pressure Low Temperature treatment on the properties of dairy based, emulsified frozen food foam and the equivalent non aerated liquid system. Special emphasis was put on the freezing behavior under pressure, sensorial properties, the air cell distribution and ice crystal size and distribution. In cooperation with a leading ice cream manufacturer potential benefits of HPLT processing of dairy based foam products, that may give rise for further scientific work in this field, were identified and described.

► HPLT treatment of aerated dairy emulsions.
► Overrun retention after HPLT freezing.
► HPLT induced ice crystal properties.
► Superior smoothness and mouth coating after HPLT treatment.
► New process method for frozen dairy foams.