Drying without the freeze

Using proprietary technologies developed in conjunction with the University of British Columbia, Canadian company EnWave is focused on the development of new methods of dehydrating food and biological materials, using radiant energy vacuum technology.

Radiant energy vacuum (REV) technology combines microwaves, as a radiant energy source, with vacuum, to achieve rapid, highly controlled dehydration at, or below, room temperatures. Food products including fruit, vegetables, probiotics, enzymes, proteins and food cultures, as well as vaccines and antibodies, can be dried using this technology. The dried products are free of additives, colouring agents and preservatives and they retain most of their original nutrition and colour.

The technology is straightforward in concept, involving a microwave generator connected to a vacuum chamber, where the food is rotated in order to ensure even exposure to the microwaves.

The key is the vacuum chamber, which is where EnWave’s technology is claimed to have a significant edge over conventional freeze drying. The pressure in the vacuum chamber is reduced until the boiling point of water is about body temperature - so the product is dried without the use of heat. The problem with vacuum is that it reduces the transfer of energy - it doesn’t cross a vacuum well, except for radiant energy. EnWave overcomes this problem by using microwave as a source of radiant energy.

Practically, product can be economically dried in 10 to 15 minutes and the system is continuous rather than batch based.

Rapid dehydration in a vacuum means there’s no time for food to spoil: no opportunity for oxidisation to turn apple slices brown because there’s no oxygen to set it off, no moisture to allow microorganisms to release enzymes that cause food to decay.

The REV method is claimed to be faster than freeze drying by several orders of magnitude.

EnWave claims capital costs are about a sixth of freeze drying while energy costs are about a third. The food is comparable in nutritional value and taste and in some cases looks better, the company says.

The company now has three distinct divisions: nutraREV for food dehydration, powderREV for the dehydration of bulk food cultures, probiotics and fine biochemicals such as enzymes, and bioREV and freezeREV for live or active pharmaceutical dehydration.

nutraREV

Fruits, vegetables, low-fat snacks, herbs, meats and seafood can be dehydrated using a combination of vacuum pressure and microwave energy at, or below, room temperatures.

In 2008, EnWave built the first continuous nutraREV machine capable of commercial production levels of dried berries. In March 2009, EnWave completed the sale of this technology to partner Calsan Enterprises, a major blueberry producer in Richmond, British Columbia. Together, the two companies have proven that a marketable, dried berry can be produced in commercial quantities using this technology.

In-laboratory tests are claimed to have proven that the nutraREV process can have the following benefits over freeze drying:

• high-speed processing in minutes rather than hours or days
• reduction in energy usage, start-up costs and machinery footprint
• improved retention of flavour and colour
• reduced potential for large batch losses with continuous processing
• potential for creation of new product attributes such as ‘puffing’
• potential for improved rehydration characteristics
• manufacturer control over final moisture content

The technology is now being marketed by EnWave in North America for the dehydration of products such as berries, sour cherries, herbs, potatoes, tomatoes and onions.

The company also has a co-marketing agreement with German engineering group Hans Binder Maschinenbau to sell and service nutraREV technology in Europe. The goal of the agreement is to accelerate revenue growth by each company, and to provide local machine service for their customers in the food sector in Europe and North America.

EnWave’s nutraREV and Binder’s MIVAP technologies both produce attractive dried food products with high nutritional retention, improved flavour and appearance, and cost savings in labour, energy and capital per kilogram of production over freeze drying.

Although both companies use microwaves as an energy source, EnWave’s continuous rotating basket design and Binder’s continuous tray system both offer proprietary advantages, with limited market overlap, for dehydrating a wide range of fruit, vegetable and meat products for the snack, cereal, soup and baking industries.

powderREV

The latest addition to EnWave’s platform of REV technologies is powderREV which dehydrates a continuous stream of liquid using microwave energy as a heating source in a low-pressure vacuum environment. This technology is designed for the bulk dehydration of starter cultures, probiotics and fine biochemicals such as enzymes.

In April 2009, EnWave successfully completed the first phase of a series of tests with partner Danisco. Together, the two companies will create a dehydration method delivering high-speed continuous bulk powder processing capable of handling sensitive biological materials, such as cultures.

Based on the success of these early results, EnWave and Danisco are now undertaking the second phase of testing to evaluate the commercial viability of powderREV dehydration technology on a wider scope. EnWave and Danisco expect this second phase to be completed during 2010.

bioREV and freezeREV

EnWave’s proprietary REV technology combines microwave energy with vacuum pressure to produce high-speed dehydration of live or active pharmaceuticals in sterile vials. This process is particularly suitable for creating room-temperature stable pharmaceuticals containing live organisms, such as viruses, bacteria and antibodies, where an emphasis must be placed on maintaining the maximum possible survival rates of these organisms until they are delivered to a patient.

Production of dried vaccines storable at room temperatures for long periods of time would be considered a major industry breakthrough. Dried vaccines with long shelf life could be shipped worldwide, stored without the need for expensive, constant refrigeration, and stockpiled to protect against pandemic diseases and bioterrorism.

The current standard for dehydrating many liquid pharmaceuticals is freeze drying (lyophilisation).

This process is expensive, time consuming and often results in significant loss of live organism activity during dehydration.

EnWave has developed two versions of REV for use in drying live or active pharmaceuticals:

• bioREV - a dehydration method for materials which require a gentler drying process without extreme temperature changes or freezing.
• freezeREV - a dehydration method for frozen material where low moisture levels in the final product are imperative for long product shelf life.

Both methods dry material in minutes, compared to days required for conventional freeze drying, and both technologies are designed to offer the potential for significant reductions in processing costs through labour, raw material, energy and time savings.

bioREV and freezeREV technology is currently available as a single-vial prototype to collaboration partners.

EnWave

www.enwave.net