• thermal processing

Thermal Processing

Over the past 25 years, H.G. Molenaar has established itself as the indisputable leader in the field of in-container food and beverage thermal processing systems. Our leading products include Batch Retorts and Tunnel Pasteurizers.

Process Laboratory

Our new Thermal Process Laboratory allows customers to perform in-container heat penetration studies using both Rotary and Static Simulators, coupled with the latest measuring instruments and thermal process simulation software.

A Tunnel Pasteurizer simulator is also available to perform heat penetration tests for products such as beer, fruit juice or other high-acid food packaged products. Accelerated shelf life trials can be conducted in our incubator.

Customers from around the world have used our invaluable pilot facility in order to establish key processes. And by working closely with our clients, we are able to tailor designs to suit the customer’s exact requirements.

Retorts for batch sterilization

H.G. Molenaar has three different models of retorts namely static (steam/air), full water immersion with cage rotation and super heated water spray. The static retorts are manufactured in either vertical or horizontal configuration. Carbon steel or stainless steel construction is possible. Trolleys are used to load the baskets into horizontal retorts. Gantry systems are usually employed for loading baskets in vertical retorts.



Tunnel_Pasteurizer1 (1)With more than 50 years worth of thermal process experience, H.G. Molenaar has become a leader in the design and manufacture of Tunnel Pasteurizers. Our multi-zone design features a regenerative recirculation system where heating and cooling zones interact – resulting in substantial energy savings.

Typical applications are the in-container pasteurization of bottled juices, beer, high-acid canned products, pickled vegetables and more. Suitable containers include glass or PET bottles, cans or pouches.

Machine Design

Tunnel_Pasteurizer2 (1)

Product is transported through the pasteurizing tunnel by an Intralox modular conveyor belt. The tunnel is divided into several heating and cooling zones, each with a separate sump, re-circulating pump and cascade shower trays. As the product passes through the tunnel, it travels underneath the shower trays and is subjected to a particular zone shower temperature. In this way, it is first heated (pasteurized) and later cooled.

The heating medium (steam) is separated from the pasteurizing water by a plate heat exchanger. Cooling water can also be separated if required.

Energy Considerations

By employing regenerative zones in our design, energy consumption is effectively minimized. Typical regenerative energy consumption of a Molenaar pasteurizer is as follows:

Beer 122 KJ/I
Fruit Juice 144 KJ/I
Carbonated Juice 197 KJ/I

Pasteurizer Simulator

Our Pasteurizer Simulator is an exact small-scale replica of our pasteurizers. Products can be tested in our simulator to develop thermal processes. With a given temperature profile, the accumulated pasteurizing units (PU) can be calculated and the process verified or thereafter refined. Once the desired process is determined, it can be incorporated into the design of the commercial production machine.