Finally, the proposed method was applied to analyse the
effluents generated at different stages of a CIP process in a pilot
plant aimed at the manufacturing of cheese. As an example, in
Fig. 7 are shown the spectra obtained for some samples analysed.
One of the register (7a) corresponds to the sample which contained
the highest fat content. This sample was collected during
the intermediate rinsing step, and it had to be diluted with water
(factor dilution, 1:10) to adjust the fat content to the linear
working interval. The fat content found for this sample was
(7977) mg/L (n¼3). The other two samples were collected during
the wash (7b) and final rinsing (7c) steps; the spectra showed that
these samples contained fat levels below the LOQ and below the
LOD, respectively. Some of the samples analysed contained a
significant amount of suspended solids. However, these samples
could be easily passed through the membranes, and reproducible
absorbances were measured after an effective sample
homogenization.