Classification of Bitter Orange Essential Oils According to Fruit Ripening Stage by Untargeted Chemical Profiling and Machine Learning.

Saeedeh Taghadomi-Saberi,Morteza Sadeghi,Santiago Marco,Amin Allah Masoumi,Sílvia Mas Garcia

doi:10.3390/s18061922

Abstract

The quality and composition of bitter orange essential oils (EOs) strongly depend on the ripening stage of the citrus fruit. The concentration of volatile compounds and consequently its organoleptic perception varies. While this can be detected by trained humans, we propose an objective approach for assessing the bitter orange from the volatile composition of their EO. The method is based on the combined use of headspace gas chromatography–mass spectrometry (HS-GC-MS) and artificial neural networks (ANN) for predictive modeling. Data obtained from the analysis of HS-GC-MS were preprocessed to select relevant peaks in the total ion chromatogram as input features for ANN. Results showed that key volatile compounds have enough predictive power to accurately classify the EO, according to their ripening stage for different applications. A sensitivity analysis detected the key compounds to identify the ripening stage. This study provides a novel strategy for the quality control of bitter orange EO without subjective methods.

Highlights

Essential oils (EOs) and their volatile fraction have been known since ancient times to have broad applications in prevention and therapy for human health [1]
The obtained results show that the ripening degree can be predicted from key volatile compounds in the bitter orange essential oils (EOs) headspace using gas chromatography mass spectrometry, avoiding the need for sensorial analysis by trained human panels
The proposed methodology combines chromatographic fingerprinting followed by data analysis using machine learning techniques, in particular artificial neural networks (ANN)

Summary

Introduction

Essential oils (EOs) and their volatile fraction have been known since ancient times to have broad applications in prevention and therapy for human health [1]. EOs from Citrus genus are the most popular EOs and are the largest proportion of natural flavors and fragrances [4]. Some orange varieties such as bitter orange (Citrus aurantium) are grown primarily for their peel and the associated essential oil industrial production for citrus flavor applications [5]. Many researchers have pointed out the importance of ripening on quality attributes of citrus peels and their products such as Sensors 2018, 18, 1922; doi:10.3390/s18061922 www.mdpi.com/journal/sensors

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