## 4 Use of Spectroscopic Techniques for Monitoring Changes in Muscle Foods during Processing
### Meat and Poultry Products
#### 4.2.2 Non-Thermal Treatments
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Muscle Foods** & **Analytical Technique** & **Chemometric Tool** & **Main Findings** & **Reference** \\ \hline \hline \multirow{3}{*}{Pork batters} & NMR, FT-IR & ANOVA & With increasing temperatures, bonded-water converted into free water, WHC increased significantly, and \(a\)-helix transformed into \(\beta\)-sheets. Correlations were observed between spectral data and traditional parameters & [219] \\  & & & LF-NMR \(T_{2}\) relaxation is highly correlated to sensory attributes of \(\beta\)-back. Reduction in Injules and pancreas at 75 \(\times\) 8 compared to 65 C was attributed to changes in the size of the pores confining the myofibrular water within the meat in combination with an exposition of water & [224] \\  & & Fluorescence & ANOVA & Oxidative damages increased with increasing cooking temperatures and cooking times & [215] \\  & & & & \(1\) was possible to classify stored samples according to cooking temperatures (below or above 65 C) & [225] \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & & \\  & & & &  
Other studies have investigated the impact of storage under MAP or other conditions on the quality of meats. For instance, being stored under MAP, meat is prone to changes in color; consequently, Vis spectroscopy could represent an alternative ally to inspect the quality of stored meat. This premise has been confirmed by [PERSON] and collaborators, who collected Vis spectra on pork steaks stored at diverse conditions in terms of storage time and MAP (atmosphere: 0%, 40%, 50%, or 80% of oxygen; light: yes or no; storage time: up to 9 days) [233]. PCA unveiled that color modifications occurred at any level of oxygen and they were influenced by all the three investigated factors (i.e., MAP, time, and light). In the same study, PLS-DA was successfully used to classify samples according to the different storage conditions, confirming the outcomes obtained by the PCA models. In addition to playing a key role in studying the effects of HPP and MAP, FT-IR spectroscopy is a suitable ally also for investigating the effect cold-plasma on meat products. An example of its exploitation is given by the study conducted by [PERSON] and collaborator who used FT-IR coupled with NMR and chromatography to inspect the modification induced by cold plasma on beef fats [234]. The authors found that the formation of hydroperoxides, along with the other oxidation products (e.g., ozonides, aldehydes, carboxylic acids), determined from the spectral results were proportional to the treatment time and its voltage. The IR spectra of beef fat treated by cold plasma-dielectric barrier discharge ((60-80 kV) and treatment duration in the range of 3-30 min at temperature of 16-18 \({}^{\circ}\)C) indicated a decrease in C=C (at 723, 1650, and 3008 cm\({}^{-1}\)) with the increase in treatment intensity [234]. However, using the spectra data in the region between 1800 and 700 cm\({}^{-1}\) in a PCA analysis was not successful in separating beef plasma treated samples and controls. The effect of another non-thermal treatment, the ultrasounds, has been investigated by [PERSON] et al. [235]. In this study, FT-IR was used to monitor the modifications induced in beef meat following the use of power ultrasound intensity (PUS). The study showed that the application of PUS induced proteins aggregation, with a transformation of \(\alpha\)-helix in \(\beta\)-sheets, leading to the formation of free radicals. Lipid and protein oxidation were also significantly increased as a result of application of PUS. In another study, IR thermographic imaging was used to determine the heat transfer from the surface of samples to a surrounding medium and the heat transfer from the inner of the sample to its surface [236]. The technique was used to investigate the effect of ultrasound treatment (25 and 130 kHz) on the chilling of chicken breast.