Application of whiteness meter type MB

The whiteness meter is designed to measure the light reflection coefficient of samples of flour and other food products. The measured value of the reflection coefficient allows the classification of the tested sample according to standard requirements. Flour whiteness determines colour brightness, that is the degree of its brightening or darkening. It depends on two independent factors: brightness and yellow colour degree. It was recognised that brightness itself depends on, in particular, the content of crushed husks in flour and granulation degree. The yellow colour degree of flour results from content of carotenoids and xanthophyl in wheat and also intensity of possible whitening of the flour with both natural and artificial agents. On a proposal put forward by the Research Institute of the Bakery Industry in Bydgoszcz, whiteness determination was introduced into Polish Standards No. PN-A-74029 in April 1999 following an evaluation of the method of precision performed on the instrument – whiteness meters type MB-3M. The evaluation of the obtained results was prepared on the basis of ISO 5725 standard: accuracy (trueness and precision) of measurement methods and results.

Principle of operation

The method using the meter MB-3M consists in measurement of light density reflected from the surface with luminous flux of wavelength equal to 565 nm. Analysis of the reflected light density in relation to falling light density after conversion into an electric signal is carried out in a microprocessor system based on a single-chip processor SAB 80 C515A. The system assigns a successive number (1-100) to each measurement, and a number with the measurement result is entered into the system's memory together with additional information in the form of date and time of the measurement. Operation of the meter is very simple: pressing an ON/OFF button to establish communication with the microprocessor system via an alphanumeric display and keypad with four buttons. All functions i.e. measurement, scrolling of measurement results, autocalibration, reset and input of gauge values are carried out automatically by pressing the suitable push button following set of the gauge and its entrance into the whiteness memory. Next, measurements of whiteness are taken by means of a probe located directly in the analyzed flour sample.

The obtained reading is presented directly on the reader or printed, and the data is useful and easily-convertible into the flour type on the basis of the prepared table adjusted to flour types sold in Poland.

Construction

The meter consists of 2 basic parts: measuring head equipped with radiation source and electric attachment equipped with digital indicator for direct reading of light reflection whiteness with accuracy in decimal points.

The meter is provided with the verified whiteness gauge made of sintered PTFE powder by the Central Office of Measurement in Warsaw. Each gauge is provided with a certificate of calibration including data on the reflection coefficient, but the value taken into consideration for entering into the system's memory is the underlined value.   The flour whiteness meter is equipped with one whiteness gauge as standard. However, on customer request, it can be equipped with a spare gauge which can be used in the case of damage or submission of the first gauge for verification.