# Application of Spectroscopy in Food Analysis: Volume II
###### Abstract  
The _[PERSON]_-_  
demonstrated that Vis/NIR spectroscopy coupled with multiple linear regressions (MLR) can be used on potato tubers to assess their postharvest storage life, whereas its combination with partial least squares discriminant analysis (PLS-DA) represents a suitable tool for cultivar discrimination [4].  
The work from [PERSON] and collaborators [5] proposes a portable Raman-based tool to estimate the maturity of fruits containing carotenoids. Hot pepper samples were analyzed using a Raman instrument, and then the spectra were processed by means of PCA, showing clear grouping tendencies according to their ripening. From the intensity of the signals at 1156 cm\({}^{-1}\), 1515 cm\({}^{-1}\), and 1001 cm\({}^{-1}\), the authors also derive a maturity index which allows the assessment of the maturities of different carotenoid-containing fruits. One of the main practical outcomes of this tool is that it can be used in greenhouses or in automatic harvesting processes to assist with fruit picking.  
A similar purpose has been investigated by [PERSON] et al. [6] who have developed a FT-MIR, FT-NIR, and FT-Raman approach finalized to the optimization of the picking of _Pleurotus ostreatus_ mushrooms. In fact, they have demonstrated that the vibrational spectra of basidiocarp samples handled by PLS can be used to quantify protein and total glucan contents, and, therefore, this approach can be exploited to assess the quality of mushrooms as culinary ingredients.  
The synergy between FT-NIR and PLS was also exploited by [PERSON] et al. [7] in order to develop a method that allows the quantification of total sugars in various breakfast cereals. Briefly, 164 breakfast cereal samples were analyzed using a miniaturized FT-NIR. Reference analysis for sucrose, glucose, fructose, and total sugars was carried out using high-performance liquid chromatography (HPLC). Eventually, PLS was used to assess individual and total sugars based on the NIR spectra. The authors concluded that the proposed approach represents an efficient and rapid alternative to standard methods for the quantification of individual and total sugar content in breakfast cereals.  
The coupling of FT-NIR and PLS was also exploited in the work published by [PERSON] et al. [8] who have relied this efficient combination for the quantification of dry matter, protein, and starch content in fresh yam samples. Eventually, they demonstrated that the coupling of FT-NIR (collected on blended yam) and PLS represents a suitable alternative to the wet-chemistry procedure.  
The last paper belonging to this group is the one from [PERSON] and collaborators [9] who have developed a spectroscopy-based procedure for the prediction of the frying time of various edible oils. To achieve this goal, 15 frying cycles were carried out using 3 different oils: soybean, peanut, and rapeseed. FT-NIR spectra were collected on oils after each frying cycle. Eventually, the correlation coefficient between the sequence of frying times and absorbance was used to select characteristic wavelengths which were at the basis of a differential prediction model for the estimation of frying time. The proposed approach led to a prediction accuracy of 100% \(\pm\) 1 cycle.