mouth-feel of the finished product. Furthermore, failure to adequately stabilise the water phase can result in too much water being squeezed out in the final, crystallised product. The next challenge for the team, then, was to stabilise this phase. And sodium alginate (E401) was chosen to do the job. Sodium alginate is one of a group of commonly used stabilizers that thickens the water phase, stabilising it in very low-fat spreads and reducing the risk of water being squeezed out. In addition, sodium alginate improves mouth-feel for this type of spread. The optimal effect was found at 0.55%, while at 0.75%, the water droplets became too viscous and the spread started to become less stable with a higher risk of free water. 18-22°C 18-22°C Low Fat Spread 60-65°C Cooling 22-25°C Figure 3: Process flow chart of a low fat spread emulsion CHALLENGE 6: CREATING OPTIMAL CONDITIONS FOR SUCCESS Once the basic recipe was decided upon by the team, it was thoroughly tested in our large-scale margarine pilot plant with the aim of confirming exactly the right processing parameters. The process of manufacturing these low fat spreads is the opposite of what is traditionally used when making a 40% spread. So practical experience from producing 40% low fat spreads cannot be used in the production of very low fat spread emulsions. Figure 3 shows the process flow used to successfully manufacture a 10% low fat spread. The water phase needs to be added slowly, but the emulsion itself tends to thicken in very low fat spreads if mechanical treatment is too intensive. As Figure 4 shows, doubling the agitation in a pre-emulsifying unit can increase the viscosity up to five times. Stirrers that work well when making 30-40% low fat spread emulsions need to be re-designed for more viscous emulsions, otherwise “dead” areas will arise in the emulsion tank. We used anchor stirrers with success, making sure to agitate slowly so as to avoid the build-up of too viscous emulsions. Keeping the temperature at 55–65o Celsius in the emulsion and buffer tanks is important for reducing the risk of highly viscous emulsions. Otherwise the viscous emulsion may become so thick that it can’t be pumped from the tanks. This is also why pin machines are not necessary in the production flow. Thanks to the cooling capacity in the water phase, production capacity can be high and packing temperatures don’t need to be very low. The crystallisation part of the process is important, but in a different way to high-fat margarine products. That’s because in lowfat spreads the fat crystals do not dominate the structure in the same way as in margarine and butter. The tightly packed water droplets produce a W/O emulsion with a more mayonnaise-like structure. In high-fat margarines, mouth-feel is affected by the melting crystals and the subsequent phase inversion of the emulsion. Low-fat products and their very strong emulsifier systems reduce the instability effect purely because the fat crystals melt down without the same effect in high-fat products. Figure 4 Viscosity in low fat spread emulsions 30000 25000 20000 15000 10000 5000 0 300 350 400 450 500 550 600 CHALLENGE 7: STORAGE FOR A STABLE, SPREADABLE RESULT The final part of the project was to determine the storage parameters that would make sure the product could achieve optimal final properties and maintain these properties as well as possible from the factory to the consumer’s table. Low-fat spreads are sensitive to r/min cp
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