Production of Margarine and Low Fat Spreads
Originally invented as an inexpensive substitute for butter, margarine today is purchased because of its spreadability and the health benefits associated with using vegetable oil-based ingredients vs. the highly saturated fat content in butter.
Margarine is typically a water (20%) and oil (80%) emulsion with added salt, flavoring, color and preservatives. The preparation of margarine is traditionally manufactured by:
- Blending base stocks plus other oil-soluble components.
- Mixing milk or water with salt and other water soluble ingredients.
- Mixing the two phases to form a water/oil emulsion.
- Chilling and plasticizing the emulsion.
Traditional Manufacturing Process
Many of the low fat spreads have similar ingredients but the oil content can vary dramatically ranging as low as 20%. In these low oil emulsions, gums and thickeners replace the fat as an emulsifier and thickener.
Using conventional mixers and agitators presents several challenges:
- Additives designed to thicken the product are by nature liable to form agglomerates, which a conventional mixer cannot easily break down
- Partially hydrated ingredients can build up on vessel walls and the mixer shaft
- Poor hydration may lead to unsatisfactory "mouthfeel" and an unstable product leading to storage problems once the product has been opened
- Long processing times are often required to complete hydration
- Emulsions are not easily formed with conventional agitators even with additional heat
Quadro Ytron mixers are able to overcome all the above challenges. Batch size, formulation, type of ingredients and viscosity of the end product dictate the selection of equipment (Jet Mixer, ZC Powder Disperser, Z Emulsifier or a combination of equipment). For the production of the typical water/oil (20/80) emulsion, Quadro recommends the combination of Jet Mixer with a bypass assembly and the Z Emulsifier.
The solution is prepared by dispersing the powders via the bypass assembly on the Jet Mixer. Oil is then added to the vessel and the axial flow pattern of the Jet Mixer ensures an instant homogenous pre-blend which is pumped through the 3 stage high shear Z Emulsifer to provide a single pass finished emulsion.
For low fat applications incorporating gums, Quadro recommends the combined use of ZC Powder Disperser and Jet Mixer. The ZC is designed to disperse extremely difficult to wet powders in a single pass without agglomerates.
Powder incorporation can be completed during the water addition phase or in recirculation from the vessel. It is achieved by the presence of significant vacuum in the reactor generated by a liquid seal created between the rotor and stator. The powders are then subjected to enough shear to provide a single pass complete wetting before hydration is completed and retuned to the processing vessel. Oil is then added to the vessel and the jet Mixer provides the homogeneous pre-blend before recirculating through the high shear ZC to provide the finished emulsion.