Experiment 14 Measuring Overrun

Balance capable of reading to 1 g Large container of chilled water 

determine the density of the unaerated mix [by weighing a known volume (density, p ix=mass/volume]. If you are using ice cream bought from a shop let some of it melt and measure its density, being careful to ensure that no air bubbles remain. 

A typical factory made ice cream has an overrun of 100%. Home made ice cream often has a lower overrun since the method of aeration is less sophisticated. 

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Repeat using ice creams with different overruns, or use the same ice cream but let it warm up between sets of measurements. Plot a graph of the penetration depth against overrun (which you can measure using the method of Experiment 14) or temperature. 

Evaluate the samples for some of the sensory parameters discussed in Chapter 6. It is easiest to focus on one or two parameters at a time, and compare two samples. If you compare a premium ice cream and a cheap one, the differences should be clear. You could also compare ice cream made from the two mixes in Experiment 8, or fresh ice cream with ice cream that has been kept in the freezer for a long time. See how the sensory measurements of lightness and firmness compare with measurements of overrun and hardness from Experiments 14 and 15. 

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