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

T1807

Sigma-Aldrich

L-(+)-Tartaric acid, BioXtra

33801

Sigma-Aldrich

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

74860

Sigma-Aldrich

(±)-2-Octanol, ≥96.0% (GC)

251380

Sigma-Aldrich

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

27506

Sigma-Aldrich

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

W304409

Sigma-Aldrich

L-(+)-Tartaric acid, ≥99.7%, FCC, FG

57325-U

Supelco

SPME Fiber Assembly Kit, Assortment #4, Fused Silica (1 cm), size 24 ga, Autosampler, pk of 3

57551-U

Supelco

SPME Fiber Assembly Kit, Assortment, StableFlex (1 cm), needle size 24 ga, Autosampler, pk of 4

57287-U

Supelco

SPME Fiber Assembly Kit, Assortment #4, Fused Silica (1 cm), needle size 23 ga, Autosampler, pk of 3

57284-U

Supelco

SPME Fiber Assembly Kit, Assortment, StableFlex (1 cm), needle size 23 ga, Autosampler, pk of 4

57286-U

Supelco

SPME Fiber Assembly Kit, Assortment #2, Fused Silica (1 cm), needle size 23 ga, Autosampler, pk of 3

57324-U

Supelco

SPME Fiber Assembly Kit, Assortment #4, Fused Silica (1 cm), size 24 ga, Manual Holder, pk of 3

57320-U

Supelco

SPME Fiber Assembly Kit, Assortment #2, Fused Silica (1 cm), needle size 24 ga, Manual Holder, pk of 3

57550-U

Supelco

SPME Fiber Assembly Kit, Assortment, StableFlex (1 cm), needle size 24 ga, Manual Holder, pk of 4

57321-U

Supelco

SPME Fiber Assembly Kit, Assortment #2, Fused Silica (1 cm), size 24 ga, Autosampler, pk of 3

57306

Supelco

SPME Fiber Assembly Kit, Assortment #1, Fused Silica (1 cm), needle size 24 ga, Manual Holder, pk of 3

T109

Sigma-Aldrich

L-(+)-Tartaric acid, ≥99.5%

M3933

Sigma-Aldrich

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

E7023

Sigma-Aldrich

Ethyl alcohol, Pure 200 proof, Molecular Biology

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

57311

Supelco

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

57307

Supelco

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

CRM47523

Supelco

2-Methylisoborneol solution, certified reference material, TraceCERT^®, 100 μg/mL in methanol, ampule of 1 mL

W280523

Sigma-Aldrich

1-Octen-3-ol, natural, ≥95%, FG