Definition:
The volumetric increase in soft-serve product from liquid to solid state due to the incorporation of air into the frozen product. Overrun is stated as a percentage. This means that for every fluid measure of product being dispensed through the freezer, the volume yield will be increased by a defined percentage.
Common Problems Associated With Overrun
Periods of inactivity, not dispensing product, cause the air to be beaten out of the mix in the freezing cylinder. As the product loses consistency, the control systems tell the machine that the cycle needs to be reactivated, and the circle continues. Many times, we have customers that complain about soft-product, and they often request service on the equipment. In the past, SaniServ service agents have made adjustments on the equipment relating to the torque control, and in doing so they adjust the system to make the product thicker which means that the dasher assembly will run a longer cycle before deactivating.
During the dasher cycle, the refrigeration system is also activated and the longer the refrigeration compressor runs, the colder the product in the freezing cylinder gets. At some point the product gets so cold that the system freezes up, which can cause harm to the machine, the components and take the machine out of operation.
Before any adjustments are made to the system we must determine the product temperature, the rate of draw from the machine and any periods of inactivity. Chances are that the product in the freezing cylinder is soft because the overrun has been beaten out of the product over time, and the AccuFreeze system senses the product needs to be thicker. Additionally, the solution to this may be a simple as draining the product from the freezing cylinder to allow fresh mix to enter and letting the machine run through it's initial pull down cycle (which should take approximately 8-15 minutes).
Overrun Calculation
Sample Calculation
Weight of Liquid Mix (minus) Weight of Frozen Product (divided by) Weight of Frozen Product (multiplied by) 100.
[(WLM - WFM) / WFM] X 100 = Overrun %
If the liquid mix in a cup weighs 23 ounces and a cup full of frozen mix weighs 16 ounces, then:
[(23 - 16) / 16] X 100 = 43% Overrun
Overrun has a major impact on the size the finished serving. As the percentage of overrun increases, the size of the serving also increases, but the weight remains constant. If the percentage of overrun in the finished serving decreases, so does the size of the finished serving.
A 25% increase in overrun will produce a 20% larger serving size. This is critical from the sales aspect in that the customer perceives a stronger value association with a larger portion size. Conversely, if the portion size is small, there may be a lack of value association for the dollar spent, which will have definite impact upon sales, both trial and repeat.