Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) Combined with Chemometrics Methods for the Classification of Lingzhi Species.

Yuan-Yuan Wang,Jie-Qing Li,Yuan-Zhong Wang,Hong-Gao Liu

doi:10.3390/molecules24122210

Abstract

Due to the existence of Lingzhi adulteration, there is a growing demand for species classification of medicinal mushrooms by various techniques. The objective of this study was to explore a rapid and reliable way to distinguish between different Lingzhi species and compare the influence of data pretreatment methods on the recognition results. To this end, 120 fresh fruiting bodies of Lingzhi were collected, and all of them were analyzed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). Random forest (RF), support vector machine (SVM) and partial least squares discriminant analysis (PLS-DA) classification models were established for raw and pretreated second derivative (SD) spectral matrices to authenticate different Lingzhi species. The results of multivariate statistical analysis indicated that the SD preprocessing method displayed a higher classification ability, which may be attributed to the analysis of powder samples that requires removal of overlapping peaks and baseline shifts. Compared with RF, the results of the SVM and PLS-DA methods were more satisfying, and their accuracies for the test set were both 100%. Among SVM and PLS-DA, the training set and test set accuracy of PLS-DA were both 100%. In conclusion, ATR-FTIR spectroscopy data pretreated by SD combined with PLS-DA is a simple, rapid, non-destructive and relatively inexpensive method to discriminate between mushroom species and provide a good reference to quality assessment.

Highlights

It is estimated that worldwide there are at least 12,000 species of mushrooms, of which some 2000 species are edible
ATR-FTIR combined with chemometrics methods were used to classify five species
This study revealed the powerful ability of the second derivative spectra to improve the accuracy of classification models

Summary

Introduction

It is estimated that worldwide there are at least 12,000 species of mushrooms, of which some 2000 species are edible. About 35 species of edible mushroom are commercially grown, while about 200 species of wild edible mushrooms are used for medicinal purposes [1,2]. Medicinal mushrooms have a long history of use in conventional oriental therapies, especially in China, Korea and Japan [3,4,5]. One medicinal mushroom worthy of attention is Lingzhi. Lingzhi is the Chinese name given to the Ganoderma family of mushrooms [6,7]. Lingzhi, called “God’s Herb”, are traditional Chinese medicinal fungi, which have been widely used to boost human health and longevity in China and other East Asian countries [8,9]. Modern scientific studies have confirmed that Lingzhi contain fat, dietary fiber, amino acids needed by the human body and many active ingredients such as polysaccharides, ganoderic acid, Molecules 2019, 24, 2210; doi:10.3390/molecules24122210 www.mdpi.com/journal/molecules

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