Determination of acids and volatile compounds in red Txakoli wine by high-performance liquid chromatography and gas chromatography

Determination of methanol and fusel oils in various types of wines distributed in Korea

The contents of methanol and fusel oils in various types of wines were determined using headspace-gas chromatography (HS-GC). The HS-GC analysis method showed good linearity, high precision and accuracy, and low LOQ and LOD values. The methanol content in 289 types of wines ranged from not detected (ND) to 333.84 mg/kg, and was higher in Korean grape wines than in imported grape wines. Among fusel oils, the contents of 1-propanol (23.61-84.23 mg/kg) and isobutanol (34.98-111.39 mg/kg) were slightly higher in Korean wild grape wines, whereas that of isobutanol (ND to 55.26 mg/kg) was slightly lower in Korean black raspberry wine than in the other wines. The contents of amyl alcohol were lower in Korean plum wine and Korean black raspberry wine than in all of the wines included in the present study, and highest in imported grape wines.

Changes in vineyard productive attributes and phytochemical composition of sauvignon blanc grape and wine induced by the application of silicon and calcium

BACKGROUND

It is important to increase productivity and improve plant quality at the same time as preserving the principles of safety and productivity. The present study aimed to evaluate the effects of different concentrations of sodium metasilicate and calcium chloride, applied as fertilizers, on the productivity and phytochemical characteristics of Sauvignon Blanc grapes and their respective wines.

RESULTS

The experiments were conducted using 2017 and 2018 vintages of commercial Sauvignon Blanc grapes. The treatments consisted of applying separately different concentrations of sodium metasilicate (0, 4, 8 and 12 g L^-1 ) or calcium chloride (0, 5, 10 and 15 g L^-1 ). The treatments were carried out during four phenological phases. The grapes were harvested at technical maturity and white wines were elaborated. The application of inorganic salts, silicon and calcium to the grapes had a significant effect on the vineyard productivity. The best results were obtained with 4 and 8 g L^-1 silicon and 15 g L^-1 calcium. An increase in the concentration of phenolics in the grapes was noted. These compounds have antioxidant capacity, which is one of the factors responsible for the resistance of the grapes to pathogens.

CONCLUSION

The application of 4 and 8 g L^-1 silicon and 15 g L^-1 calcium to the grapes represents a potential alternative fertilizing strategy, which could increase the plant yield without damaging the phytochemical characteristics of the fruit and its derivatives. © 2020 Society of Chemical Industry.

Polyphenolic Profiling, Browning, and Glutathione Content of Sparkling Wines Produced with Nontraditional Grape Varieties: Indicator of Quality During the Biological Aging

Sparkling wines were elaborated with the nontraditional varieties Villenave, Niagara, Manzoni, and Goethe, and monitored in relation to the changes in phenolic composition, browning index, and glutathione content during 18 months of biological aging (sur lies). Important changes in the phenolic profile, browning index, and glutathione content were observed in the sparkling wines during the over-lees aging period. The major phenolic compound in the sparkling wines was tyrosol, followed by caffeic, trans-caftaric, and gallic acids, catechin and epicatechin. The biological aging led to an increase in the individual phenolic compounds, especially caffeic, gallic, and ellagic acids, and an increase in the browning index was also observed during the aging period. Caffeic acid was significantly correlated with browning and aging period in all sparkling wines, which indicates that this compound can be useful as a quality marker to monitoring the biological aging profile of white sparkling wines. The results obtained indicate that the aging period (sur lie) had an important influence on the changes in the unique phenolic profile of the sparkling wines elaborated with nontraditional varieties. PRACTICAL APPLICATION: In sparkling wines production, the secondary fermentation occurring in the sealed bottle during the vinification contributes greatly to their quality and sensory complexity. The Vitis labrusca and hybrid grapes varieties represent most of the grapes cultivated in Brazil being employed in the elaboration of juices and wines. These varieties present a great oenological potential and have not been explored yet regarding to the production of white sparkling wines. The use of these nontraditional grape varieties cultivated in South Brazil may be a viable alternative in the production of white sparkling wines with biological aging potential and particular bioactive properties.

Changes in organic acids, polyphenolic and elemental composition of rosé sparkling wines treated with mannoproteins during over-lees aging

The effect of mannoproteins on the evolution of rosé sparkling wines during over-lees aging was investigated on the basis of the chemical characterization of polyphenols, organic acids, macro- and microelements using a combined analytical approach. Variations on these constituents were assessed using Raman and near-infrared spectroscopy. During the biological aging, caffeic acid, catechin, gallic acid and malvidin-3-O-glucoside were the most abundant polyphenolics in the rosé wines. The phenolic compound tyrosol, a fermentation derivative, was found at concentrations up to 98.07 mg L^-1. The addition of mannoproteins significantly affected the concentrations of organic acids and individual polyphenolic compounds, particularly trans-resveratrol, quercetin, catechin, p-coumaric and hydroxybenzoic acids that showed increased concentrations over time. The positive effects of mannoproteins were mainly observed at the end of the biological aging. The mineral composition remained stable, while potassium was the most abundant mineral in all wines. The observed changes involving these constituents may offer new insights on their behavior during wine aging and on the bioactive and nutritional quality of rosé sparkling wines.

Bioactive potential of Vitis labrusca L. grape juices from the Southern Region of Brazil: phenolic and elemental composition and effect on lipid peroxidation in healthy subjects

Grapes are rich in polyphenols with biologically active properties. Although the bioactive potential of grape constituents are frequently reported, the effects of Brazilian Vitis labrusca L. grape juices ingestion have not been demonstrated in humans. This study identified the phenolic and elemental composition of red and white grape juices and the effect of organic and conventional red grape juice consumption on lipid peroxidation in healthy individuals. Concentrations of anthocyanins, flavanols and phenolic acids and the in vitro antioxidant activity were significantly higher in the organic juice. The macro-elements K, Ca, Na and Mg were the most abundant minerals in all juices. The acute consumption of red grape juices promoted significant decrease of lipid peroxides in serum and TBARS levels in plasma. It is concluded that red V. labrusca L. grape juices produced in Southern Brazil showed lipid peroxidation inhibition abilities in healthy subjects, regardless of the cultivation system.

Monitoring acetaldehyde concentrations during micro-oxygenation of red wine by headspace solid-phase microextraction with on-fiber derivatization

An analytical method was developed to quantify levels of acetaldehyde in wine samples. The method utilizes headspace solid-phase microextraction with on-fiber derivatization using O-(pentafluorobenzyl)hydroxylamine and quantification by gas chromatography with flame ionization detection. The technique showed good sensitivity and reproducibility in samples of Chardonnay, Petite Sirah, and Merlot wines containing acetaldehyde at levels below the sensory threshold (40-100 ppm). The method was used to monitor acetaldehyde concentrations during the micro-oxygenation of Merlot wine in a 141 L pilot-plant experiment and a 2400 L full-scale study. In both experiments, levels of acetaldehyde remained constant for several weeks before increasing at rates of the order of 1 ppm/day. Variations in the levels of acetaldehyde present are discussed within the context of the underlying chemical reactions.