Gas chromatography-mass spectrometry method optimized using response surface modeling for the quantitation of fungal off-flavors in grapes and wine.

Gas chromatography-mass spectrometry method optimized using response surface modeling for the quantitation of fungal off-flavors in grapes and wine.

Journal of agricultural and food chemistry (2015-02-24)

Navideh Sadoughi, Leigh M Schmidtke, Guillaume Antalick, John W Blackman, Christopher C Steel

ABSTRACT

An optimized method for the quantitation of volatile compounds responsible for off-aromas, such as earthy odors, found in wine and grapes was developed. The method involved a fast and simple headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) for simultaneous determination of 2-isopropyl-3-methoxypyrazine, 2-isobutyl-3-methoxypyrazine, 3-octanone, fenchone, 1-octen-3-one, trans-2-octen-1-ol, fenchol, 1-octen-3-ol, 2-methylisoborneol, 2,4,6-trichloroanisole, geosmin, 2,4,6-tribromoanisole, and pentachloroanisole. The extraction of the temperature and time were optimized using response surface methodology in both wine base (WB) and grape base (GB). Low limits of detection (0.1-5 ng/L in WB and 0.05-1.6 in GB) and quantitation (0.3-17 in WB and 0.2-6.2 in GB) with good recoveries (83-131%) and repeatability [4.3-9.8% coefficient of variation (CV) in WB and 5.1-11.1% CV in GB] and reproducibility (3.6-10.2 in WB and 1.9-10.9 in GB) indicate that the method has excellent sensitivity and is suitable for the analysis of these off-flavor compounds in wine and grape juice samples.

MATERIALS

Product Number

Brand

Product Description

57902-U

Supelco

SPME Fiber Assembly Polydimethylsiloxane/Divinylbenzene (PDMS/DVB), d_f 65 μm(PDMS/DVB, for use with autosampler, needle size 23 ga, metal alloy fiber

41447

Supelco

L-(+)-Tartaric acid, certified reference material, TraceCERT^®, Manufactured by: Sigma-Aldrich Production GmbH, Switzerland

57311

Supelco

SPME Fiber Assembly Polydimethylsiloxane/Divinylbenzene (PDMS/DVB), d_f 65 μm(PDMS/DVB, needle size 24 ga, for use with autosampler

T109

Sigma-Aldrich

L-(+)-Tartaric acid, ≥99.5%

57307

Supelco

SPME fiber assortment kit 1, for use with autosampler, needle size 24 ga

57324-U

Supelco

SPME fiber assortment kit 4, for use with manual holder, size 24 ga

57321-U

Supelco

SPME fiber assortment kit 2, for use with autosampler, size 24 ga

57306

Supelco

SPME fiber assortment kit 1, for use with manual holder, needle size 24 ga

57325-U

Supelco

SPME fiber assortment kit 4, for use with autosampler, size 24 ga

57320-U

Supelco

SPME fiber assortment kit 2, for use with manual holder, needle size 24 ga

57551-U

Supelco

SPME StableFlex^™ fiber assortment kit, needle size 24 ga, for use with autosampler

57285-U

Supelco

SPME fiber assortment kit 1, for use with autosampler, needle size 23 ga

57286-U

Supelco

SPME fiber assortment kit 2, for use with autosampler, needle size 23 ga

57287-U

Supelco

SPME fiber assortment kit 4, for use with autosampler, needle size 23 ga

34023

Supelco

2,4,6-Trichloroanisole-d₅, PESTANAL^®, analytical standard

655147

Sigma-Aldrich

2,4,6-Trichloroanisole-d₅, 98 atom % D

27506

Sigma-Aldrich

L-(+)-Tartaric acid, puriss., meets analytical specification of Ph. Eur., NF, 99.7-100.5% (calc. to the dried substance), powder

74858

Sigma-Aldrich

(±)-2-Octanol, ReagentPlus^®, ≥99.5% (GC)

74860

Sigma-Aldrich

(±)-2-Octanol, ≥96.0% (GC)

251380

Sigma-Aldrich

L-(+)-Tartaric acid, ACS reagent, ≥99.5%

493511

Sigma-Aldrich

Ethyl alcohol, Pure, 190 proof, ACS spectrophotometric grade, 95.0%

O5284

Sigma-Aldrich

1-Octen-3-ol, 98%

W280518

Sigma-Aldrich

1-Octen-3-ol, ≥98%, FCC, FG

W304409

Sigma-Aldrich

L-(+)-Tartaric acid, ≥99.7%, FCC, FG

459836

Sigma-Aldrich

Ethyl alcohol, Pure, 200 proof, anhydrous, ≥99.5%

33801

Sigma-Aldrich

L-(+)-Tartaric acid, puriss. p.a., reag. ISO, 99.5-101.0% (calc. to the dried substance)

M3933

Sigma-Aldrich

2-Methylisoborneol solution, ~10 mg/mL in methanol, ≥98% (GC)

E2385

Supelco

Ethanol standards 10% (v/v), 10 % (v/v) in H₂O, analytical standard

57362-U

Supelco

SPME fiber assortment kit 5, needle size 23 ga, for use with autosampler

57284-U

Supelco

SPME StableFlex^™ fiber assortment kit, needle size 23 ga, for use with autosampler