In-line Moisture Research Articles

New method for computer management of baking ovens

A new method is described for computer management of baking ovens, installed by Burtons Gold Medal Biscuits as part of a company program for building quality assurance into their production operations. The method incorporates data from in-line colour and moisture sensors. The scheme was applied first to a direct gas-fired five zone oven, of a style used in many biscuit and cookie plants in Britain and the USA. The paper reviews the technical features of this type of oven, and describes in detail the introduction of closed-loop computer control. The method includes feedforward as well as feedback control; an advantage of the method is that the oven is automatically reset to a low heat input pattern during a break in production, and full heat input is automatically restored on restart.

Microwave measurement of powder moisture and density

A two-variable microwave technique, which has been suggested for density-independent in-line moisture content measurement has been studied for several brands of instant coffee and milk powder. The technique was found to provide a moisture measurement significantly less density-dependent than the usual microwave absorption method. A further refinement of the technique is reported, which not only eliminates the residual density dependence, and thus the error in the moisture measurement resulting from density variations, but also yields a simultaneous in-line determination of the bulk density of the product. The influence of temperature, solids composition and particle size of the coffee and milk powders on the calibration characteristics is also reported.