Wine Storage at Cellar vs. Room Conditions: Changes in the Aroma Composition of Riesling Wine.

Storage temperature is one of the most important factors affecting wine aging. Along with bottling parameters (type of stopper, SO2 level and dissolved O2 in wine), they determine how fast wine will evolve, reach its optimum and decline in sensory quality. At the same time, lowering of the SO2 level in wine has been a hot topic in recent years. In the current work, we investigated how Riesling wine evolved on the molecular level in warm (~25 °C) and cool (~15 °C) conditions depending on the SO2 level in the wine (low, medium and high), flushing of the bottle's headspace with CO2 and three types of stoppers (Diam 30, Diam 30 origin and Diam 5) with different OIR levels (0.8-1.3 mg) and OTR levels (0.3-0.4 mg/year). It was demonstrated that the evolution of primary and secondary aromas, wine color and low molecular weight sulfur compounds (LMWSCs) during the two years of aging mainly depended on the storage temperature. Variation in the SO2 level and CO2 in the headspace affected mostly certain LMWSCs (H2S, MeSH) and ß-damascenone. New aspects of C13-norisprenoids and monoterpenoids behavior in Riesling wine with different levels of SO2 and O2 were discussed. All three types of stoppers showed very close wine preservation properties during the two years of storage. The sensory analysis revealed that, after only six months, the warm stored wines with a low SO2 level were more oxidized and different from the samples with medium and high SO2 levels. A similar tendency was also observed for the cool stored samples.

1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) Sensory Thresholds in Riesling Wine.

1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) is an aroma compound responsible for the kerosene/petrol notes in Riesling wines. In the current article, three sensory thresholds for TDN were determined in young Riesling wine: detection threshold (about 4 µg/L), recognition threshold (10-12 µg/L), and rejection threshold (71-82 µg/L). It was demonstrated that an elevated content of free SO2 in wine may have a certain masking effect on the TDN aroma perception. In addition, the influence of wine serving temperature on the recognition of kerosene/petrol notes was studied. It was found, that a lower wine serving temperature (about 11 °C) facilitated identification of the TDN aroma compared to the same wine samples at room temperature.

An optimized method for synthesis and purification of 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN).

1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN), an aroma compound present in wine, is used for sensory and physicochemical analyses. Therefore, synthesis of TDN of high purity is required for these purposes. Optimization of TDN synthesis in order to facilitate its subsequent purification was described. As a result, ≥99.5 % of TDN purity was reached. •The possibility of using both α-ionone and ß-ionone as starting substances was demonstrated•Modifications of the use of reagents in the second and third steps of TDN synthesis were proposed.

Bottle capsules as a barrier against airborne 2,4,6-trichloroanisole.

The possibility of 2,4,6-trichloroanisole (TCA) migration through synthetic stoppers and into wine from highly contaminated air was shown by several authors. However, those experiments were usually conducted without bottle capsules, which are a common part of wine packaging. In the current study, we demonstrated that the presence of capsules (without open holes) above synthetic stoppers can reduce wine contamination by airborne d5-TCA by about 10 times or more. Generally, metallic capsules revealed better barrier properties than polyvinyl chloride counterparts. Application of EVOH film on the external surface of the polyvinyl chloride capsules usually resulted in a lower level of wine contamination. Additionally it was demonstrated, that relatively short exposure (3 months) of the bottles to highly contaminated air could cause a considerable absorption of d5-TCA by synthetic stoppers, which can subsequently lead to wine contamination after 12 months.

"Cork taint" responsible compounds. Determination of haloanisoles and halophenols in cork matrix: A review.

Analytical methods of haloanisoles and halophenols quantification in cork matrix are summarized in the current review. Sample-preparation and sample-treatment techniques have been compared and discussed from the perspective of their efficiency, time- and extractant-optimization, easiness of performance. Primary interest of these analyses usually addresses to 2,4,6-trichloroanisole (TCA), which is a major wine contaminant among haloanisoles. Two concepts of TCA determination are described in the review: releasable TCA and total TCA analyses. Chromatographic, bioanalytical and sensorial methods were compared according to their application in the cork industry and in scientific investigations. Finally, it was shown that modern analytical techniques are able to provide required sensitivity, selectivity and repeatability for haloanisoles and halophenols determination.

10-Methoxy-benzo[g]imidazo[1,2-a][1,8]naphthyridine-4-carbonitrile.

In the title compound, C(16)H(10)N(4)O, both the meth-oxy and nitrile substituents lie in the plane defined by the benzo[g]imidazo[1,2-a]-1,8-naphthyridine ring system, resulting in a nearly planar geometry for the entire mol-ecule (r.m.s. deviation of the non-H atoms from the mean plane is 0.044 Å). In the solid-state, the mol-ecules form a three-dimensional polymer through inter-molecular C-H⋯N and C-H⋯O hydrogen bonds. In addition, the packing mode results in stabilizing π-π stacking inter-actions between the asymmetric units.

14-(2,3-Dichloro-phen-yl)-9,10-dimethyl-benzimidazo[1,2-a]benzo[f][1,8]naphthyridine-6-carbonitrile.

In the title compound, C(27)H(16)Cl(2)N(4), the benzimidazo[1,2-a]benzo[f][1,8]naphthyridine system is nearly planar (r.m.s. deviation for all non-H atoms = 0.033 Å). The dichloro-phenyl substituent is rotated by -67.5 (2)° from this plane. In the crystal structure, mol-ecules form stacks along the crystallographic (100) direction due to π-π stacking inter-actions with a centroid-centroid distance of 3.4283 (9) Å.