Use of electromagnetic field at microwave frequencies, to detect food freshness, e.g. of fish, involves comparing measured and reference energy variations for statistical evaluation

摘要

A food sample is passed through an electromagnetic field, detecting transient variation over time (3) of the electromagnetic energy for comparison with corresponding data from known samples. Discrete scanned values of transient variations in all feed lines are determined as reference magnitudes, and are evaluated in relation to the sample. Direct comparisons are made of discrete scanned values of the transient variations with and without the sample. In a learning process (4), at least one parameter varies and the variation is projected or mapped as a reduced data set (6). The reduced data is assessed by regression (5, 6) weighting. The reduced data set of known parameter variants (5) is converted into an n-dimensional parameter space. From known data sets and the parameter data set of the sample under investigation, a displacement vector is determined to permit classification of the unknown food parameter (8). The feed line (or waveguide) is open-ended and touches or intersects with the sample. The high frequency energy line is partially open, and the energy/time pulse passes the sample under investigation (2). The electromagnetic field is formed by an energy feed line or waveguide.