Outer-product analysis (OPA) using PCA to study the influence of temperature on NIR spectra of water

Rapid Non-destructive Detection of Spoilage of Intact Chicken Breast Muscle Using Near-infrared and Fourier Transform Mid-infrared Spectroscopy and Multivariate Statistics

“…OPA is a method that makes it possible to emphasise coevolutions of spectral regions in signals acquired in two different domains (heterospectral) or a single domain (homospectral) following spectral perturbation by, for example, heating or cooling of a sample (Jaillais et al 2004). In simple terms, OPA analysis starts by calculating the products of the intensities in the two signal domains for each sample (Barros et al , 2002Rutledge et al 1997Rutledge et al , 2001Di Natale et al 2002).…”

“…The outer product of two signal-vectors of lengths r and c for the n samples gave n (r rows by c columns) matrices. These matrices are then unfolded to give n (1, r×c) row-vectors, which are concatenated row-wise to produce the (n, r×c) matrix, which is called the OP matrix (Jaillais et al 2004). The value of the product intensities at two frequencies depends on the absolute value of the intensity at each frequency as follows:…”

“…This approach (OPA) can reveal how the spectra vary simultaneously as a function of some property (Jaillais et al 2004), such as microbial load or the biochemical changes induced by spoilage. By combining the FT-IR and NIR signals of chicken breast fillets, an interpretation of both signals can be facilitated.…”

Principal component regression model applied to dimensionally reduced spectral fluorescent signature for the determination of organic character and THM formation potential of source water

“…Or, it identifies several principal components within a dataset that are ranked with respect to their eigenvalue proportion. This technique has many advantages including, identification and reduction of dimensionality of the dataset, determination of meaningful underlying variables, and minimization of the effect of scatters on output [7,19,20].…”

Outer Product Analysis Applied to near Infrared and Mid Infrared Spectra to Study a Spanish Protected Denomination of Origin Cheese

“…opa was employed in order to study relationship between different spectroscopy domains such as nIr, MIr, nuclear magnetic resonance (nMr) [4][5][6][7] and even for the same domain. 8,9 opa has also been applied to correlate different signals such as data recorded from liquid cromatography/mass spectrometry (lc-MS) 10 or the electronic nose. 11 In this work, two-dimensional nIr-MIr correlation spectroscopy was applied by means of opa to test its feasibility in understanding the contribution of absorption bands related to cheese components for the characterisation of protected denomination of origin (pdo) products.…”