Australian Journal of Grape and Wine Research最新文献

Background and Aims. The Mediterranean climate has been traditionally favorable for winemaking and irrigation practice has been historically avoided and even forbidden, but current productive scenarios are suffering radical changes because of global warming. Therefore, seeking sustainable approaches to improve water availability is key to obtaining high-quality wines and maintain its style, without affecting yields. Methods and Results. Here, we aim to evaluate the effect of irrigation in Merlot vineyards, on grapes production and quality, and also on wine acceptability. Field-grown grapevines from cv. “Merlot” were subjected to two different water supplies in the field: (i) nonirrigated plants and (ii) irrigated plants with 50% of crop evapotranspiration, from veraison to commercial harvest. We assessed water stress markers such as leaf relative water content, leaf hydration, and the maximum efficiency of photosystem II photochemistry, as well as grape and wine quality parameters, wine acceptability, and preference with a panel composed of 100 participants. Furthermore, we performed a systematic review study for comparison, including 9 published reports on Merlot grapevines subjected to different water regimes, oriented to improve irrigation decisions, yield, and/or quality. Results showed that half water supply on grapevines not only induced an increase in the volume and weight of grapes, but the resulting wines had a lower total acidity and showed more desirable chromatic properties, increasing colour intensity and hue, and decreasing brightness. Sensory analysis revealed that 63% of the untrained panel preferred wines from the irrigation treatment. Integrating previously reported data, it is observed that water scarcity is favorable for quality only when compared with fully irrigated vineyards. Conclusions. It is concluded that a half irrigation can be enough to improve grape quality under Mediterranean conditions, without affecting yield components and enhancing sensory characteristics that can improve wine acceptance by consumers. Water management approaches to sustainably provide this extra amount of water to irrigate field-grown grapevines under the current context of climate change are discussed. Significance of the Study. The present study’s findings provide valuable information regarding water management in Mediterranean vineyards and its effects on the suitability of these areas to maintain high-quality wine production.

Grapevine pruning is an agronomical operation required to regulate growth and yield, improve fruit quality, and maintain plant health and vigour. However, the intensification of the crop in the last decades, driven by efforts to increase productivity and decrease costs, has led to reduced attention to this operation. The aim of this study was to investigate whether different pruning styles during the first years of vineyard training affect grapevine development. Three pruning styles were followed in a newly planted cv. “Tempranillo” vineyard for four consecutive pruning seasons: (i) respectful (RESP), where pruning cuts were always made leaving protection wood between the cut and vine perennial structures, and the preferential sap flow path was chosen; (ii) aggressive (AGGR), where no protection wood was left and, when possible, the nonpreferential sap flow path was followed; and (iii) winegrape grower (WIN), where the common practices used in the area were followed, which corresponds to an intermediate style between RESP and AGGR. In general, the RESP style increased the vegetative development compared to WIN and AGGR styles over the years and produced a higher yield in the first production year, although the intensity of the effect was not the same in the two vineyards considered. This was the first effort to systematically assess the effects of respectful pruning techniques on vine vegetative growth and demonstrate scientifically its impact.

Copigmentation is a noncovalent interaction between anthocyanins and colourless copigments that stabilises the anthocyanin-coloured forms by protecting them against water attack. Copigmentation can be responsible for almost half of the colour observed in young red wines. It has been reported that flavonols are the most effective wine copigments, but studies on the influence of the structure of these copigments on the magnitude of copigmentation are scarce. However, flavonol profiles change with grape variety and can condition the colour of the resulting wines. In addition, mannoproteins (MPs) have been reported to interact with flavonoids, which, consequently, might affect the flavonol-anthocyanin interaction. The objective of the present study was to evaluate the ability of five grape flavonols (isorhamnetin, kaempferol, quercetin, syringetin, and myricetin 3-O-glucosides: I-3-glc, K-3-glc, Q-3-glc, S-3-glc, and My-3-glc) by conventional spectrophotometric measurements and CIELAB analysis to copigment with malvidin 3-O-glucoside (mv-3-glc) in the absence or presence of five different MPs (binary and ternary model systems). Among the tested flavonols, I-3-glc was the most effective copigment, whereas K-3-glc was the least one. S-3-glc and Q-3-glc showed intermediate effectiveness, but that of S-3-glc was closer to I-3-glc and that of Q-3-glc to K-3-glc. These results point out that the presence of methoxyl groups in the B-ring of the flavonol increases copigmentation magnitude. The participation of My-3-glc in copigmentation interactions seemed to be hindered by its colloidal instability. Regarding the tested MPs, they did not provoke a direct copigmentation effect, but were able to modify the magnitude of the interaction between the flavonols and the anthocyanin and, in some cases, the colloidal behaviour of coloured aggregates formed over time. Finally, the results of the additional HPLC-DAD analyses point to a greater protection of the anthocyanin against degradation in the model systems where the magnitude of copigmentation was greater.

Background and Aims. The variation of malolactic fermentation (MLF) behavior between Oenococcus oeni and Lactiplantibacillus plantarum is crucial for wine quality. This work aimed to evaluate the fermentation kinetics of preacclimatized indigenous O. oeni (strains of SD-2a and 144-46) and Lp. plantarum (strains of XJ25 and XJA2), and their effect on color, polyphenols, volatile components, and sensory characteristics of wine. Methods and Results. The changes of polyphenols, color, volatile components, and sensory properties of a low-pH Merlot wine (pH < 3.3) after MLF with indigenous O. oeni and Lp. plantarum strains were investigated and compared. O. oeni gave wine more floral and balsamic aromas and increased the proportion of co-pigmented anthocyanins. Only strain 144-46 of O. oeni could complete fermentation during 6-day MLF (final concentration of L-malic acid <0.1 g/L). However, both Lp. plantarum strains effectively and thoroughly metabolized L-malic acid within 3 days for XJA2 and 5 days for XJ25 while maintaining a substantial population of viable cells. Lp. plantarum significantly enhanced the proportion of polymerized anthocyanins and the fruity, caramel, fatty, roasted, and herbaceous notes in wine through the modification of volatile profiles. Conclusions. Lp. plantarum after preacclimation shows more robust MLF performance compared to O. oeni. O. oeni prefers to give wine more floral and balsamic aromas, and a high proportion of co-pigmented anthocyanins. Lp. plantarum prefers to give wine more herbal and chemical aromas and a high proportion of polymerized anthocyanins. Significance of the Study. Lp. plantarum after preacclimation exhibits more favorable effects on wine compared to O. oeni., suggesting its potential for industrial application.

Background and Aims. Bentonite fining is commonly used in white wine production, which can lead to the loss of wine volume and aroma compounds. Many factors influence the efficacy of bentonite fining. The effect of pH adjustment and timing of bentonite addition were studied for their combined effects on Sauvignon Blanc wine protein haze formation and bentonite requirement at microscale and commercial scale. Methods and Results. Three bentonite addition timings were conducted on a juice pH adjustment trial: before fermentation, during fermentation, and after fermentation. The hot and cold test was utilized to determine the bentonite requirement for protein stabilization. Wine proteins were analyzed using a modified Coomassie brilliant blue (CBB) assay, lithium dodecyl sulphate polyacrylamide gel electrophoresis (LDS-PAGE), and sodium dodecyl sulphate capillary gel electrophoresis (SDS-CGE). Lower juice pH (2.80 and 3.00) resulted in sluggish fermentation, whereas the presence or absence of bentonite during fermentation showed similar fermentation kinetics at each pH. The presence of bentonite remaining in contact with ferment improved the completion of fermentation for the most sluggish ferment (pH 2.80). Commercial wine made from same batch of juice was adjusted to different pH values, and low-pH wines had a lower wine protein content and an increasing protein adsorption efficiency of bentonite fining, leading to lower bentonite requirement. Conclusions. Bentonite addition during fermentation was the most efficient in protein removal but fining after fermentation required the least overall bentonite dosage. The different fermentation scales (i.e., microscale versus commercial scale) slightly affected wine protein contents but not molecular weight (MW) profiles. Protein contents and MW profiles in stabilized wines were affected by the original juice pH with more complex patterns from high-pH juice. Significance of the Study. The findings of this study provide valuable information on optimization of bentonite fining to minimize the dosage so as to reduce the loss of wine volume and quality.

The effect of three rootstocks on the responsiveness of “Superior Seedless” grapes to cold storage was investigated in this study during the growing seasons of 2021 and 2022. The “Superior Seedless” bunches were preserved for 90 days at 4 ± 1°C and 98 ± 2 relative humidity%. The “Superior Seedless” bunch response under cold storage was shown to be influenced by the rootstocks. According to the study, bunches picked from “Superior Seedless” that were grown on the “1103 Paulson” rootstocks performed better in antioxidant enzyme activities (AEAs) than bunches obtained from other rootstocks. Furthermore, during cold storage, the rates of H₂O₂ and O₂⁻generation decreased more rapidly. However, combined with a low electrolyte leakage percentage (EL%) and malondialdehyde (MDA) accumulation, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenger concentration increased during the cold storage period. Furthermore, while berry quality traits were harvested from “Superior Seedless” grafted onto “1103 Paulson” rootstock, they were improved compared to other rootstocks. The molecular docking technique is performed to evaluate the binding affinity of antioxidant enzymes with a group of intracellular ligands, including DPPH, MDA, ascorbic acid, and tartaric acid, which show great results with respect to the DPPH compound. Following these findings, it can be concluded that the influence of rootstocks on “Superior Seedless” bunch responses to low cold storage represents a novel potential natural effect of rootstocks on responding bunches of “Superior Seedless” to low cold storage.

Genetic erosion of grapevine is becoming a serious worldwide problem and preserving its germplasm is an urgent task. Chile is not an exception to this scenario, where diverse factors led by the replacement of traditional varieties by renown cultivars have reduced the vineyard diversity. Therefore, discovering and characterizing minor varieties were the main objectives of this study. In addition to the official catalogue of around 100 grapevine varieties used to produce wine, we present here 89 genotypes not previously described as present in Chile, widely dispersed in the main wine valleys, which were retrieved from vineyards, small collections, and city gardens. Strikingly, we found 49 grapevines with allele patterns not described before. Ten of these may be old European varieties; the other 39 have allele patterns similar to Criolla varieties (e.g., descendants from the crossing of European varieties born in America). A parentage analysis performed with 15 SSR markers in these 39 N.N. samples revealed that most of them are descendants of the so-called foundational varieties Listán Prieto and Muscat of Alexandria, plus others in lower proportion such as Mollar Cano and Muscat à petit grains blancs, as well as known Criollas varieties such as Italiona and Moscatel Rosado. The 89 genotypes not described in Chile structured in three distinguishable groups: Criolla varieties, Central European varieties, and a third group enriched in Iberic varieties. The prevalence of each Criolla accession was quite variable, some corresponding to a single or a few vines found at a single place, while others were spread in several vineyards, even in different valleys, suggesting they were positively selected and propagated at some time. All the new Criolla varieties were different than the recently described Criollas found in Argentina. The discovery, rescue, and documentation of this rich heritage of Vitis vinifera L. genotypes found in Chile is the first step of a long-term work that should be continued with the evaluation of their enological characteristics, yield, and optimal management systems, aiming for the diversification of the local wine industry.

Background and Aims. Salt exclusion is an important attribute for wine grapes since many countries have limits to the concentration of sodium (Na⁺) and/or chloride (Cl⁻) tolerated in wine. The aim was to investigate whole plant capacity for Na⁺ and Cl‾ exclusion and the within-plant partitioning of accumulated ions to better understand these important salt tolerance traits. Methods and Results. Rooted cuttings of 140 Ruggeri and K51-40 (good and poor shoot Cl⁻ excluders, respectively) and five hybrids from a cross between the two genotypes were used. When challenged with salinity, 140 Ruggeri limited the accumulation of Cl⁻ and Na⁺ in the stem, petioles, and laminae and had a significantly lower whole plant concentration of Cl⁻ and Na⁺ when compared to K51-40. The latter indicates that 140 Ruggeri accumulates less Cl⁻ and Na⁺ than K51-40 by a lower uptake or a potentially greater efflux by roots, or both. While K51-40 accumulated significantly more Na⁺, it was able to retrieve it from the xylem; store it in the roots, stem, and petiole; and keep the lamina concentration comparable to that of 140 Ruggeri. Petioles of all genotypes appeared to play a role in limiting Cl⁻ accumulation in laminae and particularly for K51-40, to limit Na⁺ accumulation in laminae. Conclusions. The grapevine capacity for Cl⁻ and Na⁺ exclusion can be defined primarily as the lower net accumulation on a whole plant basis, reflecting the difference between the uptake and any efflux that may occur. Lower root to shoot transport is a key factor in shoot Cl⁻ and Na⁺ exclusion. Petiole accumulation assists in limiting the Cl⁻ and Na⁺ accumulation in the laminae. Significance of the Study. The study addressed the knowledge gap by examining Cl⁻ and Na⁺ exclusion on a whole plant basis, highlighting a range of within-plant mechanisms that act in limiting the accumulation of both ions in the laminae.