New drying method on trial

A new form of drying technology could help manufacturers retain more aroma, flavour and colour in ingredients such as herbs and spices and improve efficiency.

The adsorption drying unit - developed by Dutch contract researcher TNO - is being trialled at dairy ingredients giant Friesland Foods Kievit, with a second installation to follow at bakery ingredients supplier Unifine in February.

The unit, which can be added to existing spray dryers and other dryers handling everything from fruits to herbs, spices and milk powders, recirculates moist air back into the main dryer, enabling expensive aromas and flavourings within the ingredients to be retained. It also reduced energy costs, said TNO researcher Paul Bussmann. "The adsorption dryer enables energy consumption to be substantially reduced, functional properties like food aroma, flavour and colour to be retained and the capacity of existing dryers to be boosted," he said.

He added: "The adsorption dryer ensures that the dry air has a constant moisture content and a constant temperature. This improves the dryer capacity and production yield. Since the energy from the warm, moist air can be reused in the adsorption process, energy consumption also falls."

TNO said there had been a lot of commercial interest in the technology, which has been developed over the last five years in association with Wageningen University and leading Dutch food companies but is only now ready for commercial application.

TNO, which has a division specialising in novel processing techniques including pulsed light and high pressure processing, has also pioneered the use of superheated steam in drying foods.

This helped foods such as dried fruits used in breakfast cereals retain more nutrients such as vitamin C by reducing the risk of oxidation, said TNO.