Classification of chocolate according to its cocoa percentage by using Terahertz time-domain spectroscopy

Abstract

Feasibility of a non-destructive classification of chocolate based on its cocoa content was examined by using a Terahertz timedomain spectroscopy system combined with a multivariate analysis. For this purpose, the spectra from 0.5 THz to 10 THz of 5 chocolate samples (50%, 60%, 70%, 80% and 90% of cocoa) were examined. The acquired data matrices were analyzed by using a Fourier Transform, obtaining the dielectric function and the absorbance curve. Based on the latter, samples were classified by using 24 models of mathematical classification, achieving differences of around 93% through the model of Gaussian SVM algorithm with a kernel scale of 0.35 and a one-against-one multiclass method. This was reduced by using a Main Component Analysis, obtaining most of the spectral variations with PC1 (63.8%) and PC2 (36.2%). It was concluded that the combined processing and classification of images obtained from Terahertz time-domain spectroscopy, as well as the use of machine learning algorithms, can be used to successfully classify chocolates with different percentages of cocoa.

Necessity of Log(1/R) and Kubelka-Munk transformation in chemometrics analysis to predict white rice flour adulteration in brown rice flour using visible-near-infrared spectroscopy

“…Food adulteration will affect the physicochemical properties of the product, physical characteristics, sensory, presence of bioactive compounds, and a food allergen, which is related to the right of consumers to guarantee food safety, quality, and authenticity. Vis-NIR spectroscopy will enhance the method of classifying food products (Chen et al, 2006;Cruz, 2007;Rahmawati et al, 2022;Zhang et al, 2023;Zhou et al, 2023) and identifying the quality parameters of powder products as a way of smart authentication (Masithoh et al, 2022; Necessity of Log(1/R) and Kubelka-Munk transformation in chemometrics analysis to predict white rice flour adulteration in brown rice flour using visible-near-infrared spectroscopy 2018Rodríguez et al, 2019;Roosmayanti et al, 2021;Xu et al, 2013).…”

Terahertz wideband wave plates designed by stacking multilayered metasurface with different geometries

“…Terahertz (THz) wave has excellent properties such as low photon energy, a characteristic absorption spectrum for most polar molecules, strong penetration for nonpolar substances, and very high sensitivity to weak resonance, making it the best tool for spectral analysis, 1,2 imaging, 3–5 sensing, 6 detection, 7–9 communication, 10 and other fields 11–13 …”