The heat treatment system (pictured right) comprises two sets of vibrating coils. As the nuts and seeds travel through the first set, steam and hot air are injected, effectively killing off pathogens such as Salmonella, Listeria and E.coli.
As they pass through the second set, cold air is introduced to cool them down again. The machine, which should be up and running by August, can also be used for toasting and roasting.
Unlike other batch-based heat treatment systems, in which the foods to be treated remain static, the new device keeps them moving, ensuring a more even result. It also helped to preserve essential oils and maintain the physical integrity of the products, Whitworths technical director John McAughtrie told FoodManufacture.co.uk.
"It's a far more gentle process, but also quicker, that gives us far more control (previously the firm was outsourcing the heat treatment process to a third party) from an operational point of view."
He added: “The investment will enable us to mitigate against the risks associated with processing nuts and seeds which are imported into the UK from numerous sources around the world, with inherent microbiological issues.”
The system would also improve quality and consistency, and increase operational flexibility, he claimed.
“Its operating parameters can be finely-tuned to deliver the correct level of microbiological management. Moisture content can be finely adjusted by a cooling system which optimises product quality and shelf-life.”
Separately, Whitworths is also investing in an autonomous processing plant for peanut products and raw materials containing peanut allergens.
The cash will be spent on new mixing capabilities, weigh heads, packing and warehousing facilities, revealed McAughtrie.