May 5/Guelph, Canada/Food Weekly News -- According to recent research from Guelph, Canada, "The development of a structural fat network in ice cream as influenced by the solid:liquid fat ratio at the time of freezing/whipping was investigated. The solid fat content was varied with blends of a hard fraction of palm kernel oil (PKO) and high-oleic sunflower oil ranging from 40% to 100% PKO."
"Fat globule size and adsorbed protein levels in mix and overrun, fat destabilization, meltdown resistance, and air bubble size in ice cream were measured. It was found that blends comprising 60% to 80% solid fat produced the highest rates of fat destabilization that could be described as partial coalescence (as opposed to coalescence), lowest rates of meltdown, and smallest air bubble sizes. Lower levels of solid fat produced fat destabilization that was better characterized as coalescence, leading to loss of structural integrity, whereas higher levels of solid fat led to lower levels of fat network formation and thus also to reduced structural integrity.
"Practical Application: Blends of highly saturated palm kernel oil and monounsaturated high-oleic sunflower oil were used to modify the solid: liquid ratio of fat blends used for ice cream manufacture. Blends that contained 60% to 80% solid fat at freezing/whipping temperatures produced optimal structures leading to low rates of meltdown," wrote K.K. Sung and colleagues, University of Guelph.
The researchers concluded, "This provides a useful reference for manufacturers to help in the selection of appropriate fat blends for nondairy-fat ice cream."
Sung and colleagues published their study in the Journal of Food Science ("Effect of Solid Fat Content on Structure in Ice Creams Containing Palm Kernel Oil and High-Oleic Sunflower Oil." Journal of Food Science, 2010;75(3):C274-C279).
For additional information, contact H.D. Goff, University of Guelph, Dept. of Food Science, Guelph, ON N1G 2W1, Canada.
From the May 10, 2010, Prepared Foods E-dition