Characterization of Volatile Organic Compounds in ‘Rossa di Tropea’ Onion by Means of Headspace Solid-Phase Microextraction Gas Chromatography–Mass Spectrometry (HS/SPME GC–MS) and Sensory Analysis

Anna Taglienti,Amalia Piscopo,Fabrizio Araniti,Antonio Tiberini

doi:10.3390/agronomy11050874

Abstract

Background: Plant viral infections induce changes in the host plant, which can potentially impact composition, organoleptic properties, and storability characteristics of plant products. In particular, onion odor and flavor are determined mainly by volatile organic compounds, and changes upon infection with onion yellow dwarf virus may deeply influence these characters. Methods: A time-course study of volatile organic compounds in onion yellow dwarf virus-infected versus healthy ‘Rossa di Tropea’ onion bulbs was performed using headspace solid-phase microextraction gas chromatography–mass spectrometry; sensory analysis performed at marketability stage of onion production was used to correlate such changes to the taste characteristics perceived by consumers. Results: Volatile organic compounds regulated in infection conditions were identified, mainly belonging to mono- and poly-sulfides classes. The most abundant compounds in the analyzed samples were propyl disulfide, allyl-isopropyl disulfide, and propanethiol; significantly different concentrations were observed for 7 out of 11 VOCs in virus-infected compared to healthy bulbs. Statistical analysis based on a partial least squares discriminant analysis model and hierarchical cluster analysis allowed us to cluster samples based on phytosanitary status and storage time and to identify the most responsible compounds for such classification. Conclusions: Onion yellow dwarf virus infection induces changes in volatile organic compounds in onion during storage. The impact of such regulated compounds on ‘Rossa di Tropea’ onion odor and flavor and correlation with sensory analysis are discussed.

Highlights

In recent years, globalization and international trade have led to market saturation, for agricultural food products, with a flattening of varieties and diversity due to the demanding global scale intensive productions [1]
A time-course study of volatile organic compounds in onion yellow dwarf virus-infected versus healthy ‘Rossa di Tropea’ onion bulbs was performed using headspace solid-phase microextraction gas chromatography–mass spectrometry; sensory analysis performed at marketability stage of onion production was used to correlate such changes to the taste characteristics perceived by consumers
The sulfur compounds profile may change among different varieties within onion species [17,18], some of them being appreciated for their peculiar taste characters.’Rossa di Tropea’ onion is one of these varieties of choice; it is a production of particular interest whose cropping area is circumscribed in a small area of Calabria (Southern Italy)

Summary

Introduction

Globalization and international trade have led to market saturation, for agricultural food products, with a flattening of varieties and diversity due to the demanding global scale intensive productions [1]. Within 30 min after tissue crushing, thiosulfinates undergo further rearrangements, mainly producing mono- and polysulfides, which are referred to as “secondary” aroma compounds [12,13] This pattern of compounds and reactions is common to most Allium species; the differences in the sulfur compounds profile, impacting flavor among the species, are due to the structure and relative amounts of residues in the ACSO precursors [14]. The sulfur compounds profile may change among different varieties within onion species [17,18], some of them being appreciated for their peculiar taste characters.’Rossa di Tropea’ onion is one of these varieties of choice; it is a production of particular interest whose cropping area is circumscribed in a small area of Calabria (Southern Italy) It is characterized by pink/red colored bulbs, worldwide known for their organoleptic features as mild to sweet flavor and their high content in flavonols and anthocyanins. The impact of such regulated compounds on ‘Rossa di Tropea’ onion odor and flavor and correlation with sensory analysis are discussed

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