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Did you know that in every soft ice cream machine, air is incorporated into the ice cream mix during the freezing process ensuring an increase in volume? We explain what’s behind it and how it works.

Feeding soft ice cream with a certain percentage of air is called overrun. This overrun is an important and natural component of the ice cream. A freshly dispensed 150 ml portion of ice cream with an overrun of approx. 80 % consists of for example, 83 ml ice cream mix and 67 ml air (83 ml x 1.8 = 150 ml). Conventional ice cream has an overrun of only 30 – 45 % at a consumption temperature of approx. -18°C.

The structure of the soft ice cream is creamier due to the higher overrun and even contains fewer calories. In combination with the higher dispensing temperature of about -6°C, it feels less cold in the mouth and the flavours of the ice cream are perceived better. The tiny air bubbles trapped in the ice cream also lighten the vanilla ice cream, which has a brilliant white colour. And let’s not forget: The cost of goods is reduced with every percentage point of a higher overrun. The return on investment improves!

However, the amount of possible overrun has its limits. With more than 90 – 100 % overrun, further improvement in taste and sensory characteristics can no longer be achieved. On the contrary: it changes to the opposite – the structure of the ice cream becomes shaving-foam-like and the taste diminishes.

How does the air get into the ice cream?

Basically, there are three different systems for introducing air into soft ice cream machines. All systems have in common that there is a storage container above the freezing cylinder. An agitator in the cylinder scrapes off the ice that freezes on the wall. At the same time, the ice mix is foamed with air. As there is overpressure in the freezing cylinder, the enclosed gas bubbles expand when the ice cream is dispensed. The storage container is connected to the freezing cylinder via a pipe and stores chilled ice cream mix.

1. Gravity system

Here, both the ice-cream mix and the air are fed automatically from the storage container into the freezing cylinder via a pipe. Above the mix level, the ambient air is passively mixed into the mix via an adjustable nozzle. This system is cost-effective. However, it only achieves a low overrun of max. 20 - 30 %.

2. Pump system

In this system, a gear pump is located in the storage container above the mix level. This actively delivers a mix-air mixture to the freezing cylinder via a connecting pipe. The required air is also taken from above the mix level. When the pump is not in operation, a non-return valve prevents the mix from flowing back into the storage container. The amount of air supplied can be adjusted via various nozzle sizes. An overrun of around 80 % can be achieved. However, this begins to diminish after about two to four years, resulting in poorer material usage. Spare parts for the pump system are comparatively expensive.

3. Overpressure system (Luna system)

In the overpressure system used in LUMEN ice cream machines, the storage container and freezing cylinder are connected to each other via an inlet elbow and form a closed system. A common, adjustable overpressure prevails inside. Filtered ambient air is fed to the freezing cylinder by means of an air compressor via a non-return valve. Excess compressed air that is not required for the overrun is automatically fed into the storage container. An overrun of around 80 % can be achieved.

Advantages of the self-contained Luna system:

Due to the large number of suppliers on the market, we recommend – not least because of our 60 years of soft ice cream experience – to understand the technical approach of a soft ice cream machine before making a decision.

Wear and tear on machines is given everywhere. However, its prevention with repair and service as well as required spare parts costs different amounts of time and money. The famous “life-cycle costs”, i.e. the costs of the soft ice cream machine starting with the procurement, i.e. the purchase price, the service and any necessary repairs combined with spare parts costs, play a role that should not be underestimated in a holistic business consideration.

A long service life of the machines over decades, few necessary services to guarantee the function and care with simultaneously high load offer you a high degree of investment and planning security. The cost of sales is thus a fixed constant for years!

This is not the only reason why numerous companies from the market segment of German and international amusement parks have been customers of the LUMEN Group for many years.

Do you have questions about the Luna system? Please feel free to contact us!