Eliminate emulsifiers from ice cream.
The researchers see promise for such a two-stage approach for many novel applications. Conventional ice cream processing involves combining all ingredients and processing together, but pasteurization and homogenization are processes that can affect structure and functionality of, for example, nutraceutical incorporation. So the idea of blending liquid streams just prior to freezing--two-phase processing--may be a useful approach. Investigators demonstrated one such application by controlling protein adsorption to fat.
The researchers compared the quality of ice cream made without the added emulsifier to ice cream made conventionally with and without the emulsifier. Investigators created two-phase process ice cream by preparing two separate phases: emulsion (fat, some protein, water) and solution (remaining protein, sugar, corn syrup solids, stabilizer, water). They combined the phases just before the freezing step.
The investigators used pilot-scale ice cream manufacturing techniques to prepare ice cream according to the two-phase process concept. The quality of the product as related to fat structure was compared to ice cream made in the conventional way.
The indicators of quality that researchers relied on included the percent of fat destabilized, overrun and meltdown rate. Conventionally processed ice cream containing an emulsifier exhibited a high degree of fat destabilization, high overrun and slow meltdown rates. Ice cream produced conventionally without an emulsifier underwent little fat destabilization, had low overrun and melted rapidly.
Ice cream produced by the two-phase process had good fat destabilization and slow meltdown with moderate overrun, suggesting that this technique can be successful in promoting desirable structure in ice cream formation without added emulsifier.
Controlling the protein surface concentration on the mix emulsion droplets by restricting the amount and type of protein available upon homogenization makes it possible to form an emulsion that is quiescently stable but also which undergoes partial coalescence when sheared.
Ice cream could be produced by combining this fragile, low-protein surface concentration emulsion phase (containing all the fat and a fraction of the protein and water) with a solution of the remaining ingredients--the solution phase. Adding carrageenan in the solution phase would limit protein migration from the serum to the interface and allow a desirable amount of partial coalescence after combination of the two phases.
The two-phase process has been successfully employed to produce an acceptable ice cream with no added emulsifier that behaved similarly to a conventional emulsified product. Although the two-phase ice cream was successful from the standpoint of fat structure development, partial coalescence and the associated properties of the ice cream, questions remain before this process could be of commercial value. Other properties of ice cream not related to fat have yet to be considered, e.g., ice crystal size distribution and the susceptibility of the product to recrystallization.
The two-phase process does offer a marketing advantage in that the product could be considered all natural. However, the novel processing steps may make the two-phase process cost-prohibitive, compared to the use of egg yolk components as the emulsifier.
Further information. Doug Goff, Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada; phone: 519-824-4120; fax: 519-824-6631; email: firstname.lastname@example.org.
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|Publication:||Emerging Food R&D Report|
|Date:||Sep 1, 2003|
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