Detection of fluorescence signals from ATP in the second derivative excitation-emission matrix of a pork meat surface for cleanliness evaluation

We investigated the potential application of excitation-emission matrix (EEM) spectroscopy in the rapid, non-destructive evaluation of cleanliness in meat processing plants. ATP can be an indicator of microbial contamination. Thus, the fluorescent signal of ATP was detected at Ex = 286 nm and Em = 386 and 412 nm by applying two-dimensional Savitzky-Golay second-order differentiation of EEM obtained from the pork meat surface. The second derivative of the fluorescence intensity at Ex = 284 nm and Em = 412 nm, i.e., the wavelengths assigned to ATP, decreased with the ATP content. The ATP content and plate count were quantified using the second derivatives of EEMs by partial least squares regression in good agreement [coefficient correlation, 0.87; RMSEP, log10 (0.70, mol cm−2) for the predicted ATP content]. The model directly reflected the ATP fluorescent signal changes.