late and the water content in the chocolate will gradually increase causing a viscosity increase where especially the Yield Value (YV) (see box) in the chocolate will increase. This process is speeded up if the process parameters are not optimal e.g. too hot chocolate, the ice cream is not cold enough when dipped, and even ice cream dripping into the chocolate. A gradual increase in the Yield Value in the coating will result in gradually thicker layer, risk of pinholes, longer crystallization time and in extreme cases separation of the coating on the ice cream. An immediate and typical reaction on an increasing layer thickness is to increase the temperature in the chocolate bath. This will result in a thinner layer, but also increase the water migration and the heat damage on the ice cream is increased. Addition of more fat will also help, but naturally such adjustments are not optimal as the production should run smooth and uniform creating uniform products. Additionally, adding more vegetable fat will mean higher costs of the final ice cream, as well as difficulty setting a precise cost of the final product as the cost will fluctuate. how to Create a stable iCe Cream Coating So the big desire is to create a coating which will act the same way during the entire production run despite it is exposed to various amounts of melted ice cream mix. To meet this we need to work with emulsifiers and to create the perfect buffer against variations in the rheology a combination of emulsifiers is preferred. The following will describe the importance of using emulsifiers in ice cream coating. By sharing some experimental results with you guidelines to make the most efficient mix of emulsifiers will be given. All in all this will help you in creating an ice cream coating which is stable, uniform and very robust toward viscosity changes during a production run. introduCing emulsifiers Lecithin (E322) typically derived from soya or sunflower has traditionally been used to regulate the rheology of an ice cream coating. In chocolate, lecithin is typically dosed around 0.4% as this is where the optimal functionality is found and is this exceeded the YV will increase. In ice cream coating typically 0.7 – 0.8% is used in order to have a buffer against water migration during the production process. This is working but it is possible to achieve a far better result! 0.7% lecithin 0.7% Palsgaard® AMP 4448 yield Value (yV) is defining the force needed to initiate flow in a non Newtonian fluid like chocolate. The YV is typically important when working at low shear like moulding/vibrating. plastic Viscosity (pV) is the force needed to maintain a constant flow in a chocolate mass. The PV is important when working at medium to high shear like in the enrobing process. Ammonium phosphatide or Emulsifier YN (E442) also known as Palsgaard® AMP 4448 is a product typically made from rape seed oil and possesses a stronger functionality than lecithin. Emulsifier YN can be added in higher dosages without negative effect on the YV - the thickening effect - and is therefore very well suited for the ice cream coating application. To read more about the unique functionality of Emulsifier YN, please look at the end of this article*. testing the effeCt of emulsifiers in iCe Cream Coatings The increase in water content over a production day, depend on the production parameters and this increase can be as high as 1.5%. In order to make the trials as realistic as possible, up to 2% ice cream mix containing 63% water was added to the coating. In practice this means a max. addition of 1.3% water to the ice cream coating. Graph 1 shows the increase in viscosity at shear rate 2 [1/s] (speed of the chocolate) when applying various amounts of ice cream mix to a coating with and without lecithin or Palsgaard® AMP 4448 added. Experimentally this has been found to be the best measuring method for describing the conditions in an ice cream dipping process. It is also a good illustration of the changes which may happen during a production day. It is clear that compared to the emulsifier free ice cream coating, both the addition of lecithin and Palsgaard® Graph 1: Rheology on ice cream coating - The effect of lecithin and Palsgaard® AMP 4448. 3500 3000 2500 2000 mPa∙s 1500 1000 500 0 0% ice cream mix 1% ice cream mix 2% ice cream mix Palsgaard Technical Paper - August 2012 Moisture caused problems in ice cream coating - a problem of the past 3
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