Posted on Sep 20, 2023

What Is Overrun?

Overrun is the percentage of ice cream that is air incorporated in the product during the freezing process to expand & make more product with less materials. For example, when you make hard ice cream with an overrun of 30% that means that you have expanded the product by 30%.

Here’s another example: 1 gallon of hard ice cream mix will produce 1.3 gallons of finished hard ice cream mix. A gravity fed pump machine usually has a 25% -35% overrun versus a pressurized machine yields about 65% or more. If you want to produce premium quality soft serve ice cream, we recommend you yield a product that has 50% – 60% overrun. Another thing to keep in mind is investing in a high quality machine because the quality & functionality of the machine you use also affects the product, regardless of whether it is gravity fed or pressurized.

How Does Overrun Affect My Product?

Ice cream overrun affects smoothness, consistency & taste of the product, therefore affecting your profitability. Overrun affects your profitability because it is the amount of servings you can produce with your given materials. When your soft serve looks fluffy and stands well without dripping or falling over, you can be assured that the overrun is optimal.

A few inexperienced or first time soft serve shop owners might say that the product is “too warm” when the product is at the right temperature but doesn’t have the right amount of air content in the ice cream to give it structure & volume. Example: Whipped cream without air looks very similar to milk. After air is infused into the product, whipped cream gains volume & can be flipped upside-down.

A product mix that is beaten too much holds less air. Since some machines don’t have a high overrun, they lower the temperature more to help “stiffen” the product not realizing that this makes the product become harder & icy as well as losing the soft creamy texture and taste.

Part of how ice cream overrun affects profits is the perceived amount of product that a customer receives. At this point you have to choose to maintain product costs, you can either serve customers a small serving & risk losing and upsetting your customers or you can make your products with a higher overrun to make a smooth & creamy ice cream cone that seems generous in amount.

Different Types Of Pumps In Pressure Fed Machines

Pressure fed machines have different types of pumps to move the product mix from the reservoir to the freezing cylinder for pressurization. One type of pump uses pistons with “O” rings & check systems. Other machines use peristaltic tube which don’t need to be lubricated & have less parts, which makes it easier to clean. Depending on the brand & a machine’s pump design, the pressure ranges from 18# to 30#. The higher the pressure switch the better infusing of air in product.

The pump control system is critical in maintaining the correct pressure when combining the air and product mix. Some machines are equipped with timed pumps which activate during the product draw & stay on for a specified amount of time after the end of the draw.

This is the less desirable option. It does not account for different draw speeds or volumes. Therefore it is important to be very specific with your timing of the draw rate. This makes producing a high quality product on a consistent basis difficult. These machines time the pumps to pump more than enough air and then release the excess pressure back into the mix reservoir after every draw in order to assure the barrel is pressurized. This is a problem because it creates bubbles in the hopper and produces inconsistent overrun in your product. In a critical situation such as a lunch rush or peak hour, one moment your product is creamy and smooth, the next batch appears to be a yellowish color & more icy & stiff. This is why we recommend investing in quality brands.

How Do I Calculate the Product Mix’s Overrun?

Preliminary Steps:

Weighing a container with your product in pints and subtracting it later makes calculating product overrun easier. 

Make a note of the container’s weight filled with the liquid product mix & subtract the weight of the container. You can check both numbers to check your overrun. Fill another same size container with the same level of the finished frozen product & write down its weight. After these preliminary steps are finished you can plug in the numbers into the formula below.

Formula

 1. {(Weight of liquid mix) – (Weight of the same volume of finished product)} = x

2. {(x ‘from step one’) / (Weight of the same volume of finished product)} x 100% = Overrun percentage

Example

• Empty container = 1 oz.
• Container with liquid mix = 18 oz. (already subtracted the 1 oz. weight of the container)
• Container with finished product at same volume as liquid mix = 12 (already subtracted the 1 oz. weight of the container)

The numbers plugged into formula is:

• [(18 – 12) / 12] * 100 = 50 percent overrun

When overrun is properly understood and calculated correctly, you will save time and resources in the long run. Check out our articles and guides for more ice cream making and machine knowledge! 

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