Sairem of France and Stalam S.p.A. of Italy offers radio frequency (RF) defrosting systems for thawing or tempering seafood, meat, and vegetables.  (Tempering raises the temperature of frozen blocks of fish products to just below the freezing point to facilitate cutting and further product handling).  Their systems operate at a frequency of 27.12 MHz, are built of stainless steel for corrosion resistance, and have polyethylene conveyor belts to facilitate cleaning.  They are available with output RF power from 10 kW to 105 kW.  Units are operated in parallel for increased production volume.  RF systems are designed for continuous processes.  RF defrosting systems offer many benefits as compared to conventional systems, however, RF equipment is not widely used by Northwest food processors.  

Drawbacks of conventional defrosting methods are avoided with RF as heat is generated uniformly thus producing even drying. The system is compact, fast, and easily controlled, resulting in significant drip loss reductions while minimizing product deterioration due to bacterial growth. The RF process works even for large product blocks, and can thaw product inside packaging.

Energy savings depend both upon the system being replaced and the product type.  Conventional thawing systems utilize forced air, hot water, vacuum, or microwaves.  Microwave systems are constrained, as thawed product absorbs energy better than frozen parts, while with RF systems, temperatures are uniform within the product and produce no negative impacts on product quality.  

Non-energy benefits of RF defrosting include:

1.     Processing speed and temperature uniformity minimize the risk of product degradation and bacterial growth, even in large blocks;

2.     Product can be brought to the correct temperature needed for the next stage of processing;

3.     RF equipment requires less floor space than conventional equipment.

RF drying can be used to dry crackers, cookies, and other snack foods after they have been baked. It can also be used to dry ceramics, synthetic foam, textiles, water-based inks and adhesives in paper products. RF can also be used to preheat thermoset plastic molding compounds.