Disinfestation & Sanitisation equipment

Introduction

Insect pest infestation is a major problem in the storage, processing and marketing of agricultural commodities such as nuts, legumes, cereals, seeds, etc. Typically, chemical fumigants (like methyl bromide) are used for postharvest pest control but regulatory issues, environmental concerns, potential health hazards, reduced acceptance by consumers and the increase of the organic market have pressed the industry to implement non-chemical quarantine treatment alternatives, including thermal methods.

Conventional heating techniques are simple and easy to control, however they are intrinsically slow and it is well known that prolonged heating can be detrimental to quality of food products. Direct heating methods by electromagnetic waves, instead, allow for rapid and uniform heating of many substrates. Recently, specific research has confirmed the viability of the radio frequency technology in this application field.

Radio frequency disinfestation of dry food commodities

The effectiveness of radio frequency heating as a pest control treatment for nuts, grains and other dry agricultural commodities stands on the following experimental evidence:

• Nuts, grains, seeds etc. can be RF heated to the core from room temperature to 55-60°C in 3 to 5 minutes, i.e. 5 to 10 times faster than conventional heating;
• The above temperature level, held for not more than one or two minutes, is generally sufficient to achieve 100% mortality of even the most heat-resistant pest species in all their development stages;
• The minimal thermal impact determined by such mild temperature-time conditions, preserves at best the physical, chemical and nutritional properties of the host commodity;
• Approx. 25 kWh are required to treat 1 ton of product, which translates into a cost of EUR. 2 to 4 /ton, roughly the same as chemical fumigation or controlled atmosphere treatments.

STALAM’s “RF/G” equipment

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STALAM is proud to introduce to the world markets its revolutionary “RF/G” equipment, especially designed for the large-scale disinfestation of dry agricultural commodities.

In the “RF/G” machine the product is fed with an in-built hopper feeder to a large diameter pipe made of a RF-transparent polymeric material, through which the product is transported by means of a purposely-designed screw conveyor. This conveyor system ensures a plug flow, which is essential to achieve the target mean temperature in all the product passing through the RF electrodes, while mixing slowly but continuously the individual particles across the pipe, thus limiting drastically the temperature differences among them.

The almost complete filling of the pipe makes it impossible for the live insects to escape the treatment. Another advantage of the pipe system is that it makes it easy, if necessary, to create a controlled atmosphere (by CO2, inert gases, air at a controlled temperature and/or humidity, etc.) around and within the product being RF treated.

The final part of the pipe, not subjected to the RF field, serves as temperature hold section and, once the process is complete, the product exits the equipment through a shielded opening, ready for the next step (cooling, winnowing, storage, packing, etc.).

The screw conveying system is suitable for a large range of particle dimensions, from fine flours, through small grains and seeds, to large nuts.