Postharvest Biology and Technology 123 (2017) 1–11

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Postharvest Biology and Technology

journal homepage: www.elsevier.com/locate/postharvbio

Withering of plucked Trachelospermum jasminoides (star jasmine)

flowers – Time-dependent volatile compound profile obtained

with SPME/GC–MS and proton transfer reaction-mass

spectrometry (PTR-MS)

a, b b b b

Erna Schuhfried *, Emanuela Betta , Luca Cappellin , Eugenio Aprea , Flavia Gasperi ,

a b

Tilmann D. Märk , Franco Biasioli

a

Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Technikerstr. 25, A-6020, Innsbruck, Austria

b

Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, 38010, S Michele a/A, (TN),

Italy

A R T I C L E I N F O A B S T R A C T

Article history:

Received 11 August 2015 In this study, the automated application of proton transfer reaction-mass spectrometry (PTR-MS), SPME/

Received in revised form 27 July 2016 GC–MS (solid phase micro-extraction/gas chromatography-mass spectrometry) and multivariate data

Accepted 11 August 2016 analysis (chemometry) to the time-dependent changes of Volatile Organic Compound (VOC) patterns of

Available online 18 August 2016

Trachelospermum jasminoides (T. jasminoides) (star jasmine) flowers are studied. The withering of plucked

whole T. jasminoides flowers over a thirteen day range is investigated by monitoring the change of VOC

Keywords:

release over time since plucking. Three phases with strong differences in the quantities of VOCs between

Proton transfer reaction-mass spectrometry

measurements were seen, with a burst of VOCs at the beginning and at the end of withering. We

(PTR-MS)

tentatively identify the most abundant VOCs with PTR-MS, and verify identification with SPME/GC–MS.

Whole flower measurements

PTR-MS allows for distinguishing (without identification) 472 peaks from withering T. jasminoides which

Trachelospermum jasminoides

mostly cannot be found with SPME/GC–MS. A high fragmentation of the compounds is observed. The

Volatile organic compound (VOC)

PTR-MS data are assessed with principal component analysis and the three phases are confirmed. At the

SPME/GC–MS solid phase micro extraction/

fl

gas chromatography-mass spectrometry beginning, seemingly regular ower VOCs are emitted, while in the third phase of withering, alcohol

emission bursts towards the end point of withering. The latter can be only detected with PTR-MS. Hence,

PTR-MS and SPME/GC–MS supply complementary information. The study demonstrates the potential of

applying PTR-MS together with SPME/GC–MS to time-dependent physiological living flower experiments

and of T. jasminoides in particular, and suggests the possible use of PTR-MS fingerprinting for origin

determination and quality assessment, and studies such as plant-plant, plant-compound (hormone),

plant-animal (pollinator, herbivore) or plant-pathogen interactions.

ã 2016 Elsevier B.V. All rights reserved.

1. Introduction probably best known for the pleasant fragrance of its flowers used

as decorative vine. It is not related to true jasmine, albeit the scent

Trachelospermum jasminoides (T. jasminoides) (Jasminum trache- is somewhat similar, though star jasmine (T. jasminoides) does not

lospermum, also known as star jasmine) of the milkweed family, contain the reported indolic off-note of true jasmines at high

which has been included in the Dogbane family (Apocyanaceae), is indole concentrations. The flowers are used in the perfume

industry, and the scent has been included in at least 55

commercially sold perfumes (“Basenotes Fragrance Search,”

2014; “parfumo,” 2015), including well-known perfumes such as

Abbreviation: PTR-MS, proton transfer reaction-mass spectrometry; SPME-GC/

Bvlgari Mon Jasmin noir, Bvlgari Mon Jasmin Noir L’Elexir, Brilliant

MS, solid phase micro-extraction-gas chromatography/mass spectrometry; m/z,

mass to charge ratio; E/N, ratio electric field to number density, measured in Wish from Chopard, Japanese Cherry Blossom – Cerisier du Japon

Townsend [Td]; ppt(v), parts per trillion (volume); sccm, standard cubic centimeters

from The Body Shop, Opium Fleur de Shanghai from Yves Saint

(corresponding to mL/min); SPME, solid phase micro extraction; GC, gas

Laurent, and Pretty from Elizabeth Arden (“parfumo,” 2015). The

chromatography; PCA, principal component analysis; PC, principal component.

inner bark yields a strong fiber that is utilized for making rope,

* Corresponding author.

“

E-mail address: [email protected] (E. Schuhfried). sacks and paper ( Trachelospermum jasminoides in Flora of

http://dx.doi.org/10.1016/j.postharvbio.2016.08.006

0925-5214/ã 2016 Elsevier B.V. All rights reserved.

2 E. Schuhfried et al. / Postharvest Biology and Technology 123 (2017) 1–11

China@efloras.org,” 2013) and the stem is used for treating dependent analysis (Biasioli et al., 2011; D’Alessandro and Turlings,

rheumatism and injury in traditional Chinese medicine (Ill Chan 2006). Moreover, PTR-MS has a high sensitivity and low limit of

Noh, 2011; Sheu et al., 2009). Most publications on T. jasminoides detection (parts per trillion by volume (pptv)). One advantage of

are rather concerned about the content of the plant (Jing et al., PTR-MS is also its drawback: It does not involve a specific

2012) than about the flowers (Joulain, 1987). separation step and distinguishes between compounds only by

A particular challenging experimental task is whole flower their mass to charge (m/z) values. This makes compound

measurements. The first head space measurements on living identification tricky, as compounds typically fragment, resulting

flowers were performed by Mookherjee et al. (1989). In addition, in more than one peak per compound or several origins of the

delicate flowers are a particular challenging system: For the signal detected at a certain m/z. This leads to a lack of selectivity of

extraction of fragrant compounds special techniques have to be PTR-MS, as a trade-off for high time resolution and no required

applied. For instance, the VOCs might suffer thermal and hydrolytic sample preparation. We here apply PTR-MS in the recently

degradation and might not be resistant to basic or acidic extraction. commercially available time-of-flight (Tof) version, which partly

And hence mild and low temperature techniques such as water can overcome the lack of selectivity problem due to its higher mass

steam distillation, solvent extraction, enfleurage (Joulain, 1987) or resolution of typically 0.022 u (Fabris et al., 2010), compared to

supercritical fluid extraction (Surburg and Panten, 2006) are routinely used quadrupole based instruments.

applied. This also points at the difficulties involving the analysis of We aim at monitoring the variation of volatile organic

T. jasminoides fragrance, and all the more, T. jasminoides flowers compounds (VOCs) over time, which are emitted from intact

(Joulain, 1987). plucked flowers, and we aim to demonstrate the ability of

Recently, modern analytic techniques have been performed on automated Proton Transfer Reaction-Mass Spectrometry to per-

delicate flowers, besides state of the art gas chromatographic form whole spectrum measurements, which is also suited for

techniques. For instance, advanced SPME-GC (solid phase micro monitoring individual VOCs. Monitoring flower volatile emission

extraction-gas chromatography) technology was successfully used over time could be useful to find the moment of maximum

on true jasmine flowers (Pragadheesh et al., 2011). SPME is a pre- emission for specific compounds indicating the best physiological

concentration technique deploying adsorption to a fiber. However, state of flowers which will maximize the extraction yield of the

diverse VOC profiles have been reported, because the SPME compounds of interest. Another example could be the coupling of

technique in itself constitutes also a separation technique that online monitoring of flower emission with insect attraction/

discriminates against VOC compound classes, depending on the repulsion studies in order to understand how plants modulate

SPME fiber used (Pragadheesh et al., 2011). Discrimination can be their attraction or defense mechanisms. As complementary

somewhat alleviated by using a triphasic SPME fiber. instrumental analysis form, we perform SPME/GC–MS analysis

The T. jasminoides plant is known to contain delicate of flowers undergoing withering in parallel to the PTR-MS studies,

compounds (Jing et al., 2012; Tan et al., 2010), such as triterpenoids which allows for compound identification. We use a tri-phasic

(Tan et al., 2006) which can be easily degraded by analysis steps. fiber in order to avoid major compound discrimination. Advanced

Hence it is probable, that also the flowers contain such delicate multivariate statistical analysis (chemometrics) allows for the

compounds. A case of delicate flower compounds seems predes- identification of signals that play a role in the changes in the VOC

tined for the measurements with Proton Transfer Reaction-Mass profiles over time during withering of the plucked flowers.

Spectrometry, PTR-MS, a direct-injection mass spectrometric

technique. PTR-MS already has been very successfully applied to 2. Material and methods

non-destructive whole fruit VOC emission measurements (Aprea

et al., 2010, 2009, 2007a,b; Biasioli et al., 2006; Boschetti et al., 2.1. Materials

1999; Cappellin et al., 2012b; Carbone et al., 2006; Ezra et al., 2004;

Fadanelli et al., 2005; Granitto et al., 2007; Ting et al., 2012) and We performed measurements on withering plucked T. jasmi-

quite extensively (currently about 80 publications) to enclosed noides single flower samples for 12 d with SPME/GC–MS and in

plants and plant parts, see for some recent examples (Bracho- parallel for 13 d with PTR-MS. For SPME/GC–MS 4 single flowers

Nunez et al., 2011; Crespo et al., 2012, 2013; Danner et al., 2012; were used, for PTR-MS 10 single flowers due to the speedier

Raseetha et al., 2011; Tani et al., 2007; Trowbridge et al., 2012; analysis. The average weight standard deviation of a flower for

3

Bouvier-Brown et al., 2009; Bracho-Nunez et al., 2013; Demarcke the SPME/GC–MS measurement was 18.1 0.3 10 kg and for

3

et al., 2010), plant-insect interactions (Filella et al., 2011a; the PTR-MS measurements of 18.0 0.3 10 kg. The fully

Kreuzwieser et al., 2014), and also non-enclosed plant parts (Brilli opened flowers without brown spots were harvested the first

et al., 2011) or canopies in general (Bourtsoukidis et al., 2014; day at 9.30 a.m. and each flower was gently placed in a clean 20 mL

Bouvier-Brown et al., 2007; Fares et al., 2011; Kim et al., 2011; glass vial capped with a metal screw cap fitted with a teflon flange.

Nölscher et al., 2013; Tani and Kawawata, 2008), for recent reviews Flowers were touched only when using gloves in order to avoid



see (Blake et al., 2009; Smith and Španel, 2011). However, only few VOC transfer. Vials previously had been flushed with zero-air

applications of PTR-MS to flowers have been reported, to flowers (catalytically cleaned air of constant humidity) with an air flow of

directly (Filella et al., 2011b; Klahre et al., 2011; Misztal et al., 2010), 2000 mL/min (corresponding to sccm, standard cubic centimeter

to whole flowering branches (Abel et al., 2009), and flower VOC per minute) with an air volume of at least 10 times the volume of

emission from canopies (Misztal et al., 2010). the vial. Upon placing the flowers in the vials, the vials were again

PTR-MS deploys chemical ionization via proton transfer of the flushed with zero air in order to remove any contaminated air

VOCs instead of traditional electron ionization. This allows for a introduced by placing the flowers in the vials, again by flushing

direct gas phase sampling into the mass spectrometer at ambient with 2000 mL/min for 10 s and avoiding to aim the air flow directly

pressure. Consequently, PTR-MS is a method for the direct at the flowers. The flowers were kept at 20 C except for the short

monitoring of compounds without sample preparation. Thus no time during PTR-MS analysis and SPME equilibration and for taking

extraction technique is required, which is still required even in pictures, all of which was performed at room temperature

SPME-GC. This makes PTR-MS a particularly interesting option for (25 C). The flowers were exposed to shaded daylight and thus

detecting and monitoring delicate VOCs. Another particular continued their diurnal cycles. Flowers for SPME/GC–MS and PTR-

advantage of PTR-MS in plant studies is the fast sampling (less MS analysis were subjected to the same conditions and were stored

than one second), allowing for online analysis and fast time- together. However, as the SPME/GC–MS analysis did not flush the Download English Version: https://daneshyari.com/en/article/4517667

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