Food Authentication: Truffle (Tuber spp.) Species Differentiation by FT-NIR and Chemometrics

Abstract

Truffles are certainly the most expensive mushrooms; the price depends primarily on the species and secondly on the origin. Because of the price differences for the truffle species, food fraud is likely to occur, and the visual differentiation is difficult within the group of white and within the group of black truffles. Thus, the aim of this study was to develop a reliable method for the authentication of five commercially relevant truffle species via Fourier transform near-infrared (FT-NIR) spectroscopy as an easy to handle approach combined with chemometrics. NIR-data from 75 freeze-dried fruiting bodies were recorded. Various spectra pre-processing techniques and classification methods were compared and validated using nested cross-validation. For the white truffle species, the most expensive Tuber magnatum could be differentiated with an accuracy of 100% from Tuber borchii. Regarding the black truffle species, the relatively expensive Tuber melanosporum could be distinguished from Tuber aestivum and the Chinese truffles with an accuracy of 99%. Since the most expensive Italian Tuber magnatum is highly prone to fraud, the origin was investigated and Italian T. magnatum truffles could be differentiated from non-Italian T. magnatum truffles by 83%. Our results demonstrate the potential of FT-NIR spectroscopy for the authentication of truffle species.

Determination of the Geographical Origin of Walnuts (Juglans regia L.) Using Near-Infrared Spectroscopy and Chemometrics

“…A binning window of 20 leads to a significant reduction of information and is therefore not suitable for the pre-processing of our data. This is confirmed by the literature in which binning windows of up to ten are common [ 25 , 27 , 53 , 54 ]. Even if the use of the median spectra in combination with other pre-processing strategies leads to lower classification accuracies, this averaging method cannot be identified as the cause for low classification accuracies in general.…”

Origin Determination of Walnuts (Juglans regia L.) on a Worldwide and Regional Level by Inductively Coupled Plasma Mass Spectrometry and Chemometrics

“…It should therefore be pointed out that the model’s accuracy possesses a limited expressive power. However, this is not a generic criticism of the usage of binary classification models; such binary issues often match the authentication problems in practice—e.g., the differentiation of the most expensive white truffle from its cheaper counterfeit [ 53 ], or the distinction of a regional product with a protected geographical indication from foreign samples [ 42 ].…”

Towards a Mathematical Framework for Method Validation and Performance Characteristics of Non-targeted Methods for Food Authenticity

“…Methods involving chromatographic separation (like gas or liquid chromatography), mostly, but not exclusively, followed by (high resolution) mass spectrometry [18]. Alternatively, these can be other spectra generating methods such as nuclear magnetic resonance (NMR) [19], Fourier transform infrared (FTIR) [20], near-infrared (NIR) [21], or Raman spectroscopy [22]. In practice, NTMs are not specific to any instrument, platform, or analytical measurement principle.…”