In-line determination of moisture in margarine, using near infrared diffuse transmittance

In a pilot plant study, 36 batches of margarine were produced, with a moisture range of 14.28-21.91 weight-%. The margarine was measured in- and off-line using a near infrared (NIR) instrument and an off-line laboratory reference method. For the in-line measurements, diffuse transmittance fibre-optic probes were used. For the off-line measurements, sample cups were used. Partial least square regression of multiplicative scatter corrected NIR spectra, in the 780-1100 nm region, gave prediction errors, expressed as root mean square error of cross-validation (RMSECV) of 0.13 weight-% moisture for the in-line measurements, The corresponding validation correlation coefficient (R) was 0.998. The corresponding RMSECV and R values for the off-line measurements were 0.14 and 0.997, respectively. The prediction error results are considered to be very good. It can be concluded that in- and off-line NIR determination of moisture in margarine gave very good prediction results and could be used in production.