Bao-Qing Zhu

Influence of pre-fermentation cold maceration treatment on aroma compounds of Cabernet Sauvignon wines fermented in different industrial scale fermenters

The influence of pre-fermentation cold maceration (CM) on Cabernet Sauvignon wines fermented in two different industrial-scale fermenters was studied. CM treatment had different effects on wine aroma depending on the types of fermenter, being more effective for automatic pumping-over tank (PO-tank) than automatic punching-down tank (PD-tank). When PO-tank was used, CM-treated wine showed a decrease in some fusel alcohols (isobutanol and isopentanol) and an increase in some esters (especially acetate esters). However, no significant changes were detected in these compounds when PD-tank was used. Ethyl 2-hexenoate and diethyl succinate were decreased, while geranylacetone was increased by the CM treatment in both fermenters. β-Damascenone was increased by the CM treatment in PO-tank fermented wines but decreased in PD-tank fermented wines. The fruity, caramel and floral aroma series were enhanced while chemical series were decreased by the CM treatment in PO-tank fermented wines. The content of (Z)-6-nonen-1-ol in the final wines was positively correlated to CM treatment.

Study of free and glycosidically bound volatile compounds in air-dried raisins from three seedless grape varieties using HS–SPME with GC–MS

Volatile compounds in air-dried raisins from Turpan, China were analysed, with 77 volatiles identified in Flame Seedless, Thompson Seedless, and Crimson Seedless raisins, 37 of which had never been reported as raisin volatiles. Odour activity values (OAVs) of these volatiles were calculated; 20 compounds had OAVs above 1. The aroma characters of the three varieties were quite similar except for some differences in the intensity of each aroma character. The main free-form volatiles were ethyl acetate, hexanoic acid, (E,E)-2,4-heptadienal and geraniol, with β-damascenone, 3-ethyl-2,5-dimethylpyrazine, 1-octen-3-ol and hexanal making the highest contribution to the aroma. Fruity and floral were the main characteristics of the free-form aromas in raisins. The main bound-form volatiles were benzyl alcohol and acetoin, with β-damascenone contributing most to the bound-form aromas, enhancing the floral, fruity and fatty aroma.

Regional characteristics of anthocyanin and flavonol compounds from grapes of four Vitis vinifera varieties in five wine regions of China

Anthocyanins and flavonols are important flavonoid metabolites in grapes, making a dominant contribution to the color, the mouth feel and even the flavor of grapes and wines. The accumulation of these flavonoids in grapes is greatly influenced by a many, diverse but interacting factors, of which variety and climate are among the most important ones. In the present study, the anthocyanin and flavonol profiles of four grape varieties (Vitis vinifera L.), Cabernet Sauvignon, Carmenere, Syrah and Merlot, from five major wine regions in China were examined for two consecutive years (2006 and 2007). The results showed that the total anthocyanin content of the berry skins in these cultivars tended to increase from east to west in China, yet the proportion of the acylated anthocyanins displayed the opposite trend. It seemed possible that the western grape regions, with their high altitude and low annual rainfall, had an advantage in producing high level of anthocyanins. In addition, a high proportion of trihydroxylated flavonols were always found in the western region grapes, whereas dihydroxylated flavonols were more prominent in the lower altitude eastern regions. This suggested that the relative amounts of these flavonoid compounds may depend on their corresponding cultivar characteristics, while the amounts are more affected by the environmental factors where they were growing.

Polyphenolic Compositions and Chromatic Characteristics of Bog Bilberry Syrup Wines

Phenolic compounds determine the color quality of fruit wines. In this study, the phenolic compound content and composition, color characteristics and changes during 6 months of bottle aging were studied in wines fermented with bog bilberry syrup under three different pHs. The total anthocyanins and total phenols were around 15.12–16.23 mg/L and 475.82 to 486.50 mg GAE/L in fresh wines and declined 22%–31% and about 11% in bottle aged wines, respectively. In fresh wines, eight anthocyanins, six phenolic aids and 14 flavonols, but no flavon-3-ols were identified; Malvidin-3-O-glucoside, petunidin-3-O-glucoside and delphinium-3-O-glucoside were the predominant pigments; Chlorogentic acid was the most abundant phenolic acid, and quercetin-3-O-galactoside and myricetin-3-O-galactoside accounted for nearly 90% of the total flavonols. During 6 months of bottle storage, the amounts of all the monomeric anthocyanins and phenolic acids were reduced dramatically, while the glycosidyl flavonols remained constant or were less reduced and their corresponding aglycones increased a lot. The effects of aging on blueberry wine color were described as the loss of color intensity with a dramatic change in color hue, from initial red-purple up to final red-brick nuances, while the pH of the fermentation matrix was negatively related to the color stability of aged wine.

Identification of a Plastid-Localized Bifunctional Nerolidol/Linalool Synthase in Relation to Linalool Biosynthesis in Young Grape Berries

Monoterpenoids are a diverse class of natural products and contribute to the important varietal aroma of certain Vitis vinifera grape cultivars. Among the typical monoterpenoids, linalool exists in almost all grape varieties. A gene coding for a nerolidol/linalool (NES/LINS) synthase was evaluated in the role of linalool biosynthesis in grape berries. Enzyme activity assay of this recombinant protein revealed that it could convert geranyl diphosphate and farnesyl diphosphate into linalool and nerolidol in vitro, respectively, and thus it was named VvRILinNer. However, localization experiment showed that this enzyme was only localized to chloroplasts, which indicates that VvRILinNer functions in the linalool production in vivo. The patterns of gene expression and linalool accumulation were analyzed in the berries of three grape cultivars (“Riesling”, “Cabernet Sauvignon”, “Gewurztraminer”) with significantly different levels of monoterpenoids. The VvRILinNer was considered to be mainly responsible for the synthesis of linalool at the early developmental stage. This finding has provided us with new knowledge to uncover the complex monoterpene biosynthesis in grapes.

Differences in volatile profiles of Cabernet Sauvignon grapes grown in two distinct regions of China and their responses to weather conditions

Volatile compounds are considered important for plants to communicate with each other and interact with their environments. Most wine-producing regions in China feature a continental monsoon climate with hot-wet summers and dry-cold winters, giving grapes markedly different growing environments compared to the Mediterranean or oceanic climates described in previous reports. This study focused on comparing the volatile profiles of Vitis vinifera L. cv. Cabernet Sauvignon berries from two regions with distinct climate characteristics: Changli has a warm and semi-humid summer, and Gaotai has a cool-arid summer and a cold winter. The relationship between meteorological metrics and the concentrations of grape volatiles were also examined. In harvested grapes, benzyl alcohol, phenylethyl alcohol, 1-hexanol and 1-octen-3-ol were more abundant in the Changli berries, while hexanal, heptanal, 2-methoxy-3-isobutylpyrazine, and (E)-β-damascenone presented higher levels in the Gaotai berries. The fluctuation in the accumulation of volatile compounds observed during berry development was closely correlated with variations in short-term weather (weather in a week), especially rainfall. The concentration of some volatiles, notably aliphatic aldehydes, was significantly related to diurnal temperature differences. The variability during berry development of concentrations for compounds such as C6 volatile compounds, 2-methoxy-3-isobutylpyrazine and (E)-β-damascenone strongly depended upon weather conditions. This work expands our knowledge about the influence of continental monsoon climates on volatile compounds in developing grape berries. It will also improve the comprehension of the plant response to their surrounding environments through the accumulation of volatiles. The results will help growers to alter viticultural practices according to local conditions to improve the aromatic quality of grapes.

Acidic electrolyzed water efficiently improves the flavour of persimmon (Diospyros kaki L. cv. Mopan) wine.

The ability of acidic (AcW) and alkaline electrolyzed waters (AlW) to improve the flavour of persimmon (Diospyros kaki L.) wine was evaluated. Wines made with AcW (WAcW) were significantly better than wines made with AlW or pure water (PW) in aroma, taste, and colour. Volatile analysis showed that WAcW has high alcohol and ester contents, including 2-phenylethanol, isopentanol, isobutanol, ethyl dodecanoate, phenethyl acetate, and butanedioic acid diethyl ester. The total amino acid content of persimmon slurry soaked with AcW reached 531.2 mg/l, which was much higher than those of the slurries soaked in AlW (381.3 mg/l) and PW (182.7 mg/l). The composition of major amino acids in the AcW-soaked slurry may contribute to the strong ester flavour of WAcW. This is the first report to suggest that electrolyzed functional water (EFW) can be used to improve wine flavour, leading to the possible use of EFW in food processing.

Aromatic compounds and organoleptic features of fermented wolfberry wine: Effects of maceration time

ABSTRACT This study investigated the effect of maceration time on the physicochemical properties and aromatic composition of fermented wolfberry wine. Results showed that middle-time maceration (MM) wine showed higher level on physicochemical features. Esters contributed the most to the overall aroma of wolfberry wine, and its highest level was observed in MM wine. Difference maceration time altered the composition of acids, alcohols, aldehydes, and ketones in wine. Maceration did not alter the level of methionol, whereas MM caused a highest level of 4-vinylguaiacol in wine. Sensory evaluation revealed that MM provided wine with better flavor complexity and fruity notes.

Comparison of phenolic and chromatic characteristics of dry red wines made from native Chinese grape species and vitis vinifera

ABSTRACT The phenolic and chromatic characteristics of dry red wines made from native Chinese species (Vitis amurensis and its hybrids, and V. davidii) and V. vinifera were evaluated by high-performance liquid chromatography/triple-quadrupole tandem mass spectrometry and spectrophotometer, respectively. V. amurensis and its hybrids wines had higher phenolic percentage of non-coumaroylated 3, 5-O-diglucosidic anthocyanins, V. davidii wines had higher phenolic percentage of coumaroylated 3, 5-O-diglucosidic anthocyanins, kaempferol-3-O-glucoside, and quercetin-3-O-rhamnoside, V. vinifera wines had higher phenolic percentage offlavan-3-ols and 3-O-monoglucosidic anthocyanins. Wines of native Chinese species had relatively higher blue % value and lower red % value. By the use of principal component analysis and Pearson correlation analysis, specific phenolic compounds could be recognized as phenolic fingerprints of different wines, which not only play an important role in wine differentiation, but also explain their chromatic differences.

Free and glycosidically bound volatile compounds in sun-dried raisins made from different fragrance intensities grape varieties using a validated HS-SPME with GC–MS method

The conditions of sample pretreatments and HS-SPME for extracting volatile compounds from raisins were optimized, and the method was validated in the study. Free and glycosidically bound volatile compounds in three different fragrance intensities raisins were analysed using this method. There were 91 compounds identified, and 72, 26 and 8 of these compounds came from fresh grapes, the auto-oxidation of unsaturated fatty acids (UFAO) and the Maillard reaction, respectively. The aroma profiles of Thompson Seedless raisins (TSRs) and Centennial Seedless raisins (CSRs) were similar, while the floral, fruity, green and roasted aromas of CSRs were higher than those of TSRs due to the contributions of benzeneacetaldehyde, 2-pentylfuran, (E)-2-nonenal and 3-ethyl-2,5-dimethyl pyrazine. Decanal, rose oxide, geraniol, linalool and β-damascenone made the floral and fruity aromas of Zixiang Seedless raisins (ZSRs) greater than those in TSRs and CSRs, but the green and roasted aroma intensities of ZSRs were lower.