Development of an analytical method to determine methyl alcohol and isopropyl alcohol in food using static headspace gas chromatography.

A method to determine methanol (MeOH) and isopropyl alcohol (IPA) was developed using static headspace sampling (HSS) with gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The optimized HSS-GC and HSS-GC/MS methods were validated according to the parameters. The limit of quantification (LOQ) values for MeOH analyzed by HSS-GC/MS and HSS-GC were 0.50-0.56 and 1.97 mg/L, and the corresponding values for IPA were 0.14-0.21 and 1.51 mg/L, respectively. Recoveries were determined by spiking sample matrices, such as vinegar and tea. MeOH and IPA showed excellent recoveries of 93.80-107.60% and 93.92-104.32% with corresponding precisions of 0.51-7.38% and 0.90-7.70%, respectively. Compared to solid-phase microextraction-GC/MS and HSS-GC, the HSS-GC/MS method showed outstanding values for limit of detection and LOQ with improved precision and accuracy. This HSS-GC/MS method was successfully used to monitor residual solvents in 100 food and functional food products.

Reduction of carcinogenic 4(5)-methylimidazole in a caramel model system: influence of food additives.

The effect of various food additives on the formation of carcinogenic 4(5)-methylimidazole (4-MI) in a caramel model system was investigated. The relationship between the levels of 4-MI and various pyrazines was studied. When glucose and ammonium hydroxide were heated, the amount of 4-MI was 556 ± 1.3 µg/mL, which increased to 583 ± 2.6 µg/mL by the addition of 0.1 M of sodium sulfite. When various food additives, such as 0.1 M of iron sulfate, magnesium sulfate, zinc sulfate, tryptophan, and cysteine were added, the amount of 4-MI was reduced to 110 ± 0.7, 483 ± 2.0, 460 ± 2.0, 409 ± 4.4, and 397 ± 1.7 µg/mL, respectively. The greatest reduction, 80%, occurred with the addition of iron sulfate. Among the 12 pyrazines, 2-ethyl-6-methylpyrazine with 4-MI showed the highest correlation (r = -0.8239).

Antioxidative activity of volatile extracts isolated from Angelica tenuissimae roots, peppermint leaves, pine needles, and sweet flag leaves.

Volatile extracts were isolated from dried medicinal plants [Angelica tenuissimae roots (AT, Angelica tenuissima Nakai), peppermint leaves (PL, Mentha arvensis L.), pine needles (PN, Pinus sylvestris L.), and sweet flag leaves (SF, Acorus gramineus Rhizoma)] using steam distillation under reduced pressure, followed by continuous liquid-liquid extraction (DRP-LLE). The extracts were then analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The major volatile constituents of AT, PL, PN, and SF were 3-butylidene-4,5-dihydrophthalide (32 mg/g), menthol (18 mg/g), thunbergol (2.1 mg/g), and cis-asarone (37 mg/g), respectively. The inhibitory activity (%) of the extracts against hexanal oxidation ranged from 33 to 98% at a level of 50 microg/mL. Among the volatile extracts, PL and PN increased cell viabilities by 10 and 24%, respectively, at a dose of 1 microg/mL, compared to that of H2O2-treated brain neuroblastoma cells, SK-N-SH. However, a 20% reduction in the malonaldehyde level, an index for lipid peroxidation, was observed at only 1 microg/mL concentration of PN.