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, ß-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 Assimilable Nitrogen Supplementation on Saccharomyces cerevisiae Metabolic Response and Aromatic Profile of Moschofilero Wine.

The concentration of nitrogen in must is critical to yeast fermentation efficiency and wine aroma profile. The present work determined the effect of the amount of yeast assimilable nitrogen (YAN) on fermentation kinetics, aroma production, and gene expression patterns of the wine yeast Saccharomyces cerevisiae. Fermentations were performed under two different YAN concentrations of must. Acetate esters, linalool, and nerol appeared to be clearly affected by the different YAN levels. Real-time-PCR results revealed that the genes involved in ethyl and acetate esters production recorded, in general, higher transcript levels under high nitrogen supplementation. In addition, an up-regulation of the BGL2 and EXG1 genes, which are related to terpenes production, was observed in the case of high nitrogen content and it is well corresponded to the terpenol concentration found. Our study revealed the impact of nitrogen supplementation on yeast metabolism and its importance to adjust wine's aromatic composition and sensory profile.

Occurrence of aflatoxin B1 and ochratoxin A in dried vine fruits from Greek market.

Twenty-six samples of dried vine fruits from Athens and Thebes (Central Greece) market were simultaneously extracted and cleaned up by immunoaffinity columns and analysed for aflatoxin B1 (AFB1) and ochratoxin A (OTA). A combination of ELISA and HPLC methods was applied for the determination of AFB1. Recovery was 97.6%, RSD 6.46%, while the limit of detection (LOD) and limit of quantification (LOQ) were 0.05 µg kg(-1) and 0.09 µg kg(-1), respectively. OTA concentrations were only estimated by ELISA. Results revealed the presence of AFB1 in 23% of the samples (mean 1.4 µg AFB1 kg(-1)), but none exceeded the EU limit (2 µg AFB1 kg(-1)). However, OTA was detected in 100% of the samples (mean 47.2 µg OTA kg(-1)). Six samples were found to be contaminated at high levels (median 120.6 µg OTA kg(-1)) and 18 exceeded the EU limit (10 µg OTA kg(-1)).