Emmepiemme srl is the world's leading manufacturer of ohmic heating technology, producing a wide range of systems for the food industry and other areas.
Emmepiemme Ohmic heating is the result of a research project started in 1993, resulting in highly reliable and versatile continuous heating system.
It started as a collaboration on an R&D project. The main topic was industrial ohmic heating for the food industry. The project was set up in collaboration with a company that specialised in microwaves and food processing with expert engineers. In the early days of the collaboration, different prototypes were developed and successfully equipped for the first time in a plant from Italy, where the engineers then started a long period of evaluation with different types of food.
Initially, the research programme was independent, because in those years Ohmic heating was an embryonic technology and there was no public information about research centres. However, large companies were exploring the Ohmic process during the same period. The research initially yielded good results on the empirical tests and the technology looked promising despite being at the first level.
The main topic after the first test was the industrialisation of the process and the reliability of the equipped hardware. Materials, production processes, assembly, testing, laboratory analysis and more are the basis of the company that has grown for more than 20 years, with around 100 equipped plants on 4 continents. The research from Emmepiemme has not stopped and continues to help technological and material progress. The company continuously develops and tests new solutions for industries. The R&D activities are in fact carried out in collaboration with specialised research centres where technology and know-how are shared to improve industrial treatments and hardware.
Emmepiemme offers after-sales assistance to customers all over the world. Production processes and product specifications are strictly confidential and monitored by expert technicians without externalisation of know-how and intellectual properties.
An ohmic heater, also known as a joule heater, is an electrical heating device that uses the electrical resistance of the fluid to generate heat that is produced directly in the fluid itself using Joule effect when alternating electrical current passes through a conductive material. This is the result of transformative energy that causes a temperature rise.
The most commonly used heating techniques for liquids rely on heat transfer from a hot surface. This heat can be generated directly from an electric heating element or indirectly from a hot transport medium (e.g. steam) via a heat exchanger (e.g. tube and plate exchanger). These methods require a temperature gradient to transfer the heat to the process fluid, so the surfaces have a higher temperature than the product. This can cause surface fouling for certain products that burn on the hot surfaces, reducing heat transfer rates and negatively affecting the product. An additional heat transfer issue exists when heating highly viscous and particulate liquids where uniform heat transfer is difficult to achieve. Ohmic heaters solve the aforementioned problems by removing hot surfaces from heating the liquids.
Ohmic heating has been used in the food industry for over 20 years. Emmepiemme is highly specialised and offers different types of installations and technical solutions to ensure a reliable and efficient process.
Different types of ohmic heaters have been developed over the last two decades using new materials and advanced technology solutions that have made it possible to build heat treatment, pasteurisation, sterilisation, HTST (high temperature short time) systems for different categories of products, such as fruit puree (peach, pear, strawberry), fruit pieces (peach, pear, strawberry, pineapple, apricot), vegetable cream, vegetables (whole or pieces), spreads and cream cheese, egg products, dairy cream, seaweed, creamy sauce and vegetable sauce, minestrone, jam and syrup.
Therefore, the ohmic heater can treat both homogeneous and heterogeneous products uniformly and in a short time (from 10 to 90 seconds). For heterogeneous products, some precautions must be taken regarding the composition of the carrier fluid and which electrical properties must correspond to those of the solid particles.
Ohmic processing approaches the HTST concept to some extent. Therefore, the thermal damage of the product is remarkably reduced compared to conventional heating methods.
Especially sensory parameters such as colour, texture and taste are very satisfactory compared to the incoming fresh material.
In addition to the reported quality improvements, the industrial applications of Emmepiemme ohmic heaters pointed out additional benefits compared to conventional heating methods, including flexibility, elasticity, modular construction, compactness and other commercial advantages.
Flexibility
If the possibility is anticipated and desired in advance, a single device can be designed to be able to treat both homogeneous products and products containing particles. The treatment of products containing diversified electrical properties is also possible in the range of 1 to 30 times.
Elasticity
The absence of hot walls and rapid heating makes it possible to stop and restart operations with little difficulty and very little product damage or loss, which is impossible with conventional systems and especially with aseptic systems.
Modular construction
Emmepiemme's ohmic heating system is designed on a modular base. The single module is a 60 kW power unit. Therefore, it is possible (within a certain limit) to increase the power and capacity of the system by simply installing additional modules.
Compactness
The overall dimensions of the ohmic heater are very reduced, so it can easily be inserted even in existing lines without layout and utility issues.
Large pipe sections
The technology allows large pipe sections (from 50 to 100 mm) to be used to improve product pumping, especially for continuous installations, reducing the mechanical destruction of products due to shear.
In terms of specific products containing particles, this technology allows to achieve finished products with very large pieces (20 and even 25 mm) that are unlikely to be achieved in conventional systems, as well as products with very high drained weight up to 80-90 % (depending on the product).
Commercial benefits
Due to the improved sensory qualities and the possibilities offered by the features mentioned above, it is possible to market very competitive and even innovative products, not only in comparison to conventional processes, but also to frozen products (IQF).
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