Control of flow properties

Paul Boughton
The technique of shear testing has been utilised to optimise the flow behaviour of powdered snack flavours. The specification of these powders is extremely challenging, with the finished material 'engineered' from a mix of blended or co-process ingredients to provide not only the desired taste and fragrance, but also acceptable flow propert

If the flavour is too free-flowing it does not adhere well to the snack after blending, leading to excessive wastage and dust generation. Yet if the flavour is too cohesive or 'sticky' it will not flow reliably into the snack blender, giving inconsistent coating.

Traditionally, flow property control has been subjective, adding oil to reduce flow of blends considered to dusty or adding free flow to blends considered to 'sticky'.

The Brookfield Powder Flow Tester (Fig. 1), an automated shear tester has been used to measure the flowability of the snack flavours providing a measurement of the minimum outlet size through which a cohesive or 'sticky' powder will flow reliably under gravity. This measurement has been used to quantify the flowability of new snack flavours and to optimise additive levels on a small scale in the laboratory, prior to committing to batch manufacture.

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The Wolfson Centre for Bulk Solids Handling Technology, University of Greenwich, Chatham Maritime, Kent, UK.