Impact of accentuated cut edges (ACE) technique on volatile and sensory profiles of Shiraz wines

Insights into the evolution of certain sulfur-containing compounds during artificial ageing of Xinomavro PDO wines

Complex reactions favouring production or retention of volatile sulfur compounds (VSCs) are crucial for the development of red wine ageing bouquet. This study aimed to investigate the development of certain VSCs in Xinomavro red wines and examine the influence of grape origin on wine composition as it aged. Wines from Amyndeon and Naoussa PDO zones underwent artificial ageing for 24 days, and thiol precursors, varietal thiols, S-methyl-l-methionine (SMM), and dimethyl sulfide (DMS) were analysed periodically. Vineyard location and duration of ageing showed great influence on the analytes measured, with interactions revealed for thiol precursors but not 3-sulfanylhexan-1-ol. Changes in SMM and DMS concentrations indicated for the first time that a DMS pro-precursor may exist in bottled Xinomavro wine, with SMM acting as a degradation intermediate. Principal component analysis grouped regional Xinomavro wines according to the chemical transformations determined during bottle ageing.

Amelioration of Smoke Taint in Wine via Addition of Molecularly Imprinted Polymers during or after Fermentation

The adsorbents used to remove taint compounds from wine can also remove constituents that impart desirable color, aroma, and flavor attributes, whereas molecularly imprinted polymers (MIPs) are tailor-made to selectively bind one or more target compounds. This study evaluated the potential for MIPs to ameliorate smoke taint in wine via removal of volatile phenols during or after fermentation. The addition of MIPs to smoke-tainted Pinot Noir wine (for 24 h with stirring) achieved 35-57% removal of guaiacol, 4-methylguaiacol, cresols, and phenol, but <10% of volatile phenol glycoconjugates were removed and some wine color loss occurred. Of the MIP treatments that were subsequently applied to Semillon and Merlot fermentations or wine, MIP addition post-inoculation of yeast yielded the best outcomes, both in terms of volatile phenol removal and wine sensory profiles. Despite some impact on other aroma volatiles and red wine color, the findings demonstrate that MIPs can ameliorate smoke-tainted wine.

Assessment of the volatile and non-volatile profile of Savatiano PGI wines as affected by various terroirs in Attica, Greece

Establishing the concept of terroir in wines, combined with the exploitation of native grape varieties, is considered a viable alternative to produce quality wines for increasing interest in the wine market. The aim of this study is the characterization of Protected Geographical Indication (PGI) Savatiano white wines from different regions of Attica (Greece), through the chemical and sensory description of the aroma of wines and the determination of their phenolic profiles. The wines produced with the same vinification protocol were evaluated using the descriptive sensory analysis method while they underwent profiling of volatile and phenolic compounds by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) respectively. The presence of regional differences within the wines was also explored, elaborated with variables that contribute to their differentiation, such as soil type, monthly average temperature, and rainfall. Volatile and sensory profiles of the wines separated the regions and confirmed that sub-regional differences attributed mainly to soil characteristics affect wine aroma. The wines from the east part of Attica were higher in esters, terpenes and higher alcohols with high scores in fruity and blossoms attributes while wines from the north part of Attica presented higher intensity of mineral, nutty and herbaceous attributes. The separations based solely on the phenolic compounds concentration were less clear but a relationship was found between the content of phenolic acids and flavonoids and the studied regions. To our knowledge this is the first characterization of Savatiano PGI wines of Attica generating a fingerprint including chemical composition and sensory aroma characteristics to differentiate wines, combining this pattern with particular sub-regions.

Chemical and Sensory Characterization of Xinomavro Red Wine Using Grapes from Protected Designations of Northern Greece

Despite Xinomavro (Vitis vinifera L.) being a well-known noble red grape variety of northern Greece, little is known about its ''bouquet'' typicity. Volatile compounds of Xinomavro wines produced using a common vinification protocol were analyzed by gas chromatography-mass spectrometry and sensory descriptive analysis was carried out with a trained panel. Wines were characterized by the presence of fatty acids, ethyl and acetate esters, and alcohols, with contributions from terpenes and a volatile phenol. The most active aroma compounds were determined to be 3-methylbutyl acetate, β-damascenone, ethyl esters of octanoic and hexanoic acids, and eugenol. Those compounds positively correlated with fruity and spicy odor descriptors, with the wines being mostly characterized by five typical aroma terms: strawberry, berry fruit, spices, tomato, and green bell pepper. Partial least squares regression (PLSR) analysis was used to visualize relationship between the orthonasal sensory attributes and the volatile aroma compounds with calculated OAVs > 1. Key aroma-active volatiles in the wines were identified using GC-MS/olfactometry, providing a list of 40 compounds, among which 13 presented a modified detection frequency > 70%. This study is the first of its kind and provided strong indications regarding the aroma compounds defining the sensory characteristics of Xinomavro wines.

Impact of Japanese beetles (Popillia japonica Newman) on the chemical composition of two grape varieties (Nebbiolo and Erbaluce) grown in Italy

The effect of Japanese beetles (P. japonica) on critical quality indicators of Nebbiolo and Erbaluce grapes, specifically on their phenolic and volatile composition, was assessed. Adult beetle symptoms include extended skeletonization of leaves. Leaves are frequently left with their mid-vein intact but, when severely damaged, quickly turn brown. However, the plant tends to recover by generating a new leaf apparatus and the grapes reach ripeness. It emerged that the phenolic content of grapes produced by plants attacked by P. japonica (396 and 550 mg/kg, Nebbiolo and Erbaluce respectively) was generally higher when compared to healthy plants (266 and 188 mg/kg, Nebbiolo and Erbaluce respectively). Similarly, in the (red) Nebbiolo cultivar, the anthocyanin content was significantly lower in grapes produced with healthy plants. The influence of P. japonica on the volatile composition of Nebbiolo and Erbaluce grapes showed a total volatile fraction of affected grapes (433 and 439 µg/kg, respectively) significantly higher than the one related to healthy grapes (391 and 386 µg/kg, respectively). In response to the attack by P. japonica the plant significantly increases the content of some volatile compounds such as hexanal, (E)-2-hexenal, 1-hexanol, (E)-2-hexen-1-ol and phenyl ethyl alcohol.