A study of fat and air structures in ice cream

Three ice cream mixes of conventional composition with varying emulsifier c ontent (no emulsifier; 0.15% mono- and di-glycerides; 0.15% mono- and di-gl ycerides plus 0.06% polysorbate 80) were frozen using three different freez ing regimes (continuous freezer at low and high back pressure and batch fre ezer) in order to prepare a series of ice cream samples with varying levels of fat destabilization and foam structures. The hardened samples were view ed by thin-section transmission electron microscopy after freeze-substituti on and low-temperature embedding. The images were compared to those obtaine d by low-temperature scanning electron microscopy. The structures created b y increasing levels of fat destabilization were observed as an increasing c oncentration of discrete fat globules at the air interface and increasing c oalescence and clustering of fat globules both at the air interface and wit hin the serum phase. However, air interfaces at the highest levels of fat d estabilization were not completely covered by fat globules, nor was there e vidence of a surface layer of free fat. Air interfaces from continuous and batch freezing were similar. (C) 2000 Elsevier Science Ltd. AU rights reser ved.