Tempering machines that save time and money

Frozen products can be tempered in many ways. A French company, SAIREM, specialises in microwaves and radio frequency technologies to gently and rapidly temper frozen fish and seafood.

The sh processing industry must often deal with frozen products. As a highly perishable product sh is often frozen to preserve quality if it cannot be processed immediately or when it needs to be transported long distances. Products are also frozen because the logistics for frozen goods are far easier than those for fresh. Products may also be frozen to meet the requirements of the end consumer. e demand for frozen sh has resulted in the development of an entire industry related to freezing.

Thawing is a more complex process than freezing

And just as products need to be frozen, they also need to be defrosted, for which, too, there are a variety of techniques. awing, however, is a relatively complex process. While freezing is about reaching the target temperature as quickly as possible, thawing calls for the consideration of many more factors if the desired end result is to be obtained. Tempering procedures fall broadly under two categories. ose where the thermal energy to defrost the product is provided from the outside such as water, steam, or heated air, so that the product thaws from the outside inwards. In the second category the energy supplied generates heat directly within the product, so that it thaws on the inside and the outside at the same time. is is characteristic of thawing systems using microwaves, radio frequency or electric current.

Traditional thawing methods, such as room temperature thawing or using warm water, can be time-consuming and may result in uneven thawing, compromising the taste and texture of the sh. Radio frequency (RF) and microwaves are electromagnetic waves that have proven to be valuable in various industrial applications. eir ability to generate heat rapidly and uniformly makes them ideal for tempering frozen foods, including sh. When RF or microwaves are applied to frozen sh, they penetrate the food, causing the water molecules within to vibrate. is vibration generates heat, which results in a controlled and even tempering process.

Reduced thawing time compared to conventional treatments

One of the signi cant advantages of using RF and microwaves for sh tempering is the reduced thawing time. Compared to traditional methods, these technologies can thaw sh in a fraction of the time, ensuring faster preparation and reducing waiting times in processing companies, commercial kitchens, or restaurants.

is time-saving feature is particularly bene cial for establishments that deal with a high volume of frozen sh products. Furthermore, RF and microwaves o er improved tempering uniformity. With traditional methods, thawing sh can often result in uneven temperature distribution, leading to portions of the sh becoming partially cooked or over-thawed. In contrast, RF and microwaves provide consistent and controlled heating, eliminating the risk of overcooking while maintaining the desired texture and moisture content of the sh. As RF and microwaves can penetrate non-metallic materials, they can be used to defrost frozen products directly in their packaging such as in EPS boxes, cartons, or plastic bags. e use of RF and microwaves for sh thawing also o ers enhanced food safety. Unlike conventional thawing methods, which may require leaving the sh at room temperature for an extended period, RF and microwaves thaw sh quickly, minimizing the time during which bacteria can multiply. is reduces the risk of foodborne illnesses associated with slow thawing. e speed at which they can thaw products allows just-in-time production using frozen raw material. Moreover, RF and microwave thawing methods are energy e cient. ese technologies convert electrical energy into heat directly within the food, resulting in minimal energy wastage. Additionally, their rapid thawing capabilities reduce overall energy consumption compared to conventional methods. e space occupied by this equipment is also proportionately less than that required by conventional thawing systems using air or water. ere are thus several advantages associated with the use of radio frequency and microwaves to thaw products. e possibilities they o er has encouraged a French company, SAIREM to create thawing systems to democratise the RF and microwave technologies. Unlike conventional thawing methods RF and microwaves defrost the product evenly throughout its volume. e di erence between the two is that they operate at different frequencies, says Mathieu Deschamps, the company’s export manager, so we can o er our customers the system best suited for their purpose.

SAIREM has di erent business units and supplies its machines to a wide range of industries from chemical, to rubber or wood drying, to stone breaking. Universities and research centres are customers for its laboratory models. Plasma machines are used in the production of synthetic diamonds, and nally there is the food sector where machines are used to temper and defrost food products, cooking, heating, pasteurisation, drying and sanitisation. In the tempering application, the temperature is increased from -20 or -10 to -1 (or less) degrees C. With tempering there is no weight loss, and all the characteristics of the food are preserved, yet the product can still be worked with. After tempering a block of shrimp, for example, the product is not completely thawed yet each shrimp can be taken individually from the block. Energy consumption when bringing a product close to 0 degrees C is less than when going above this temperature. And then it takes just 5-10 minutes to temper the product.

Food safety is an important business area for the SAIREM equipment which can, for example, pasteurise ready meals or ingredients, cook or dry, eliminate insects from cereals, eliminate bacteria such as salmonella or listeria.

Time and energy savings reduce payback period

Because RF and microwaves treat the food so gently, they are particularly suited to delicate products like sh and seafood. Mathieu Deschamps, the export manager, says one of the main advantages of RF and microwaves is the time they take: 5-10 minutes. A traditional defrosting room will take much longer, perhaps a day or two, to thaw the same product. e payback time for an RF or microwave machine is short because when tempering a product there is no drip loss— the weight of the block before and after the tempering is the same— and the temperature is homogeneous throughout the block. In a conventional system the product will show temperature differences and there will be some drip loss which adds to the cost. According to Mr Deschamps, the payback period is typically 6-12 months for SAIREM equipment. Energy costs are relatively low, the machines run on electricity, which is more cost e ective than gas, he says. And thanks to the gentle and uniform treatment the product maintains its taste, texture, colour, nutrients, and organoleptic properties. Microwaves are the best for homogenous warming, better even than RF, and they work well on irregularly shaped products. On the other hand, to get the best results from RF, the products should have a regular shape such as a block. Even though this technology is several times slower than microwaves and the machines have a bigger footprint, the power e ciency is lower in an RF machine and today this is a major consideration for companies.

Microwaves can be used on a greater variety of food products

SAIREM is the only company that o ers both technologies. Most food applications today use microwaves while RF is used mainly in non-food applications, says Mr Deschamps, in the textile industry, for example, or for the drying of ceramics, wood, or cigars.

e only food application that lends itself to RF is the tempering of standard sh blocks to around -3 degrees C. For other sh and seafood—prawns, scallops, IQF sh—microwave is the preferred technology.

Food is not the biggest application in SAIREM’s portfolio, but it has grown steadily since the company took a strategic decision to focus on this area. The number of employees and the turnover have increased significantly. Machines for decontamination and food drying for example are selling more and more. SAIREM has an R&D centre where new solutions are developed and where customers can send their frozen products to be tested to see what kind of solution, microwave, or RF, and at which frequency, defrosts best. For tempering blocks, for example, a microwave at 915 MHz is most suited. In the case of ready meals, which are smaller, the frequency used is

2,450 MHz. The wavelength influences the depth of penetration which determines the most suitable frequency (as wavelength and frequency are inversely proportional to each other). One machine cannot however generate waves of different frequencies. While the company has a wide range of standard machines it also customises its equipment to meet the specific needs of its customers. As consumption of fish and seafood increases around the world, so will the need for efficient tempering solutions as well as cooking and pasteurisation of ready meals with fish and seafood.

SAIREM

82 rue Elisée Reclus 69150 Décines-Charpieu France

Tel.: +33 4 72 01 81 60 welcome@sairem.com www.sairem.com

Export Manager: Mathieu Deschamps

Products: Batch and tunnels solutions with radio frequency or microwave, generators, etc

Function: Heat treatment for different applications and products

Markets: 70 countries around the world