Wine Quality Parameters Research Articles

Зависимость качества винопродукции сорта Красностоп АЗОС от подкормок разными группами веществ

Abstraсt. The impact of climatic changes in external conditions on the terroirs of the planet forces the grape plant to acquire new properties and characteristics that can negatively affect the quality of the wine made from them. Many countries around the world are faced with the problem of producing grape raw materials with high sugar content and insufficient ripening of phenols. One of the effective methods of reducing the negative impact of unfavorable terroir factors is the use of various fertilizers, including foliar fertilizers. In viticulture at the present stage, there is no systematic scientific knowledge about the mechanisms of action of certain drugs on the quality parameters of grapes and wine. The objects of study are preparations of various spectrums of foliar action: complex amino acid-humic fertilizer with vitamins and microelements of the CAGS brand; Chlorella extract (amino acid complex, highly effective natural biostimulator of plant growth.); Agrumax (mineral complex); biodux – growth regulator arachidonic acid, a complex of biologically active polyunsaturated fatty acids of the fungus Mortierella alpina; must and wine from the Krasnostop AZOS variety. The work used: modern instrumental and analytical methods for studying fruit crops and grapes; methods of technochemical and microbiological control in winemaking; wine parameters were determined according to GOST methods and original certified methods of the winemaking center of the NCFSCHVW; polyphenolic and anthocyanin substances in wine were studied using the technique of V.G. Gerzhikova, Research Institute "Magarach". Agricultural technology is generally accepted, adapted to the local terroir. Work on studying the impact of foliar preparations on the quality of must and wine, analysis of wine materials from the Krasnostop AZOS variety and their organoleptic evaluation, allows us to conclude that with an increase in the concentration of the extract, phenolic substances, and the total content of biologically active substances in it, the hygienic value and general quality of the wine itself; the highest tasting score was given to wine samples from the variants of treating grapes with foliar preparations from the group of biologically active substances: Chlorella algae extract and Biodux. Keywords: grape quality, microfertilizers, microwinemaking, wine quality, tasting analysis Financing source: The research was carried out within the State Task of Ministry of Science and Higher Education of the Russian Federation for the FSBSI NCFSCHVW.

Assessment of Wine Quality, Traceability and Detection of Grapes Wine, Detection of Harmful Substances in Alcohol and Liquor Composition Analysis

Abstract: Wine production is the result of the interaction between various strains and grapes, and its good quality is also affected by many factors. Aureobasidium, Cladosporium, Candida, Filobasidium, Hanseniaspora, Hannaella, Saccharomyces, Wickerhamomyce, Alternaria, Starmerella, Acetobacter, Papiliotrema, Bradyrhizobium, Leuconostoclia, Gluconobacter, Comamonas, and Massilia, are significantly correlated with changes of physiological properties and volatile compounds. Phenolic compounds, shortened as phenolics, are a vital parameter to the quality of wine, and wine phenolics include two main families: non-flavonoids, which consist of hydroxybenzoic acids (HBAs), hydroxycinnamic acids (HCAs), and stilbenes, and flavonoids, comprising flavonols, flavan-3-ols, and anthocyanins. Wine quality is determined by either sensory tests or physicochemical tests, and the latter analyse the wine’s chemical parameters such as sugar, pH, and alcohol level. The most important constituents found in wine are Terpenes; Aldehydes, Pyrazines, Esters, Ketones and diketones, Mercaptans, and Lactones. In wine quality analysis, the most chief variables are volatile acidity, alcohol, sulphates, citric acid, density, total sulfur dioxide, chlorides, pH, fixed acidity, free sulfur dioxide, and residual sugar. Some classifiers utilized for wine quality prediction in machine learning are: k-Nearest Neighbor (KNN), Random Forest, Decision Tree, Support Vector Machines, Linear Regression, Stochastic Gradient Descent, Artificial Neural Networks (ANN), and Naive Bayes. This article is aimed to review wine quality parameters, detection and traceability of wine, and detection of harmful substances in alcohol and liquor composition analysis.

Influence of soil management on vegetative growth, yield, and wine quality parameters in an organic “Pedro Ximénez” vineyard: field and UAV data

The use of cover crops in vineyards is expected to increase due to the strong encouragement by European agricultural policy and their contribution to reducing soil erosion. This paper presents the results obtained over three years in a vineyard of the “Pedro Ximénez” variety organically grown in southern Spain. The influence on production, vigor, and grape quality of a seeded cover crop versus tillage was compared using field data and imagery acquired by an uncrewed aerial vehicle. The vines under tillage showed greater vegetative development and yield than those with cover crops between rows. The grapes from the vines under the cover crop treatment ripened earlier and presented higher values of total soluble solids, characteristics that can be useful in the protected designation of origin where the study field is placed. However, the strong yield reduction caused by the cover crop treatment encourages future research to explore other cover crop species that could contribute to improving soil properties without compromising the profitability of the vineyard. This is the first time that the influence of cover cropping on the agronomic and oenological parameters of organically grown white vineyard varieties such as “Pedro Ximénez” has been assessed using field and UAV data.

Ispitivanje fizičko-hemijskih parametara kvaliteta voćnih vina proizvedenih u Republici Srbiji

Fruit wines are products obtained after the processing of fruit crops which are not grapes. Water and alcohol are the most abundant constituents of fruit wines, along with biologically active compounds which are present in small amounts. Taken together, they significantly affect the physicochemical quality parameters. Before market placement, it is important to determine the physicochemical quality parameters of fruit wines. This study deals with the determination of physicochemical quality parameters in blackberry and sour cherry fruit wines produced in Serbia. The total content of acids determined by titration was in the interval from 7.37 to 9.05 g/L express to mallic acid. The pH values were from 2.75 to 3.57. The content of free SO2 is important to prevent spoilage induced by microorganisms, and it was in the range from 12.52 to 15.21 mg/L. The ethanol content of samples was in the interval from 6.87 to 13.57 % v/v. The obtained values for ethanol content were in accordance with the initial content of sugar in vinification, which was in the range from 13.8 to 24.2 ° Brix. Total phenolic content of fruit wines was from 1895.77 to 2417.21 mg/L expressed as gallic acid equivalents. All the investigated physicochemical parameters of the analyzed fruit wines, except ethanol content, were in line with the National Regulations for Quality and Other Demands for Grape Wine (National Regulations). The obtained results indicate the quality of fruit and demonstrate that all the procedures applied during wine production were conducted properly to obtain a quality final product. Ethanol content was below the minimal limit in 5 of 11 analyzed samples according to the National Regulations. This can be explained by the fact that every fruit has a different composition of natural constituents, which is a crucial reason to adopt specific regulations related to quality and other requirements for fruit wines.

Продуктивность виноградных насаждений и качество винопродукции сорта Красностоп АЗОС при некорневых подкормках разными группами веществ

As a result of global climate change towards warming, the whole world is faced with the problem of producing grape raw material with high sugar content and poor phenolic ripening. To eliminate this imbalance in the degree of ripening of grape raw material caused by natural anomalies, we tested fertilizers of various chemical and biochemical compositions and natural foliar biostimulants. The aim of the research was to study the effect of preparations of different spectrum of foliar action on the harmonization of sugar accumulation and phenolic ripening in grapes, and the quality of wine of the variety Krasnostop AZOS. In the current situation of unstable weather conditions in the existing terroir conditions with the established varietal composition of the vineyards, it is very relevant to identify preparations that can optimize the processes of grape ripening to preserve the quality parameters of wine. Preparations with various spectrums of foliar action will be studied: CAGS complex amino acid-humic fertilizer with vitamins and microelements; Chlorella extract (an amino acid complex from algae, the extract of which is a highly effective biostimulant); Agrumax (mineral complex); Biodux – a derivative of the fungus Mortierella alpina, a biologically active preparation of arachidonic acid; technical red grape variety bred by AZOSViV – branch of the FSBSI NCFCHVW “Krasnostop AZOS”; must and wine from the variety Krasnostop AZOS. Methods of technochemical and microbiological control in winemaking were applied in the work; wine parameters were determined according to GOST methods and original certified methods of the Instrument-Analytical winemaking center of the NCFCHVW; polyphenolic and anthocyanin substances in wine were studied using the technique of V.G. Gerzhikova, Research Institute “Magarach”. Agricultural technology is generally accepted, adapted to the local terroir. Work on studying radically different active substance preparations for the quality of grapes and wine showed that the highest statistically proven yield of the variety Krasnostop AZOS, statistically proven at the 95% significance level, was recorded as a result of application of the preparations CAGS and Biodux; the analysis of wines from the variety Krasnostop AZOS and their organoleptic evaluation allows us to conclude that with the increase of the concentration of the extract, phenolic substances, and the total content of biologically active substances in it, the hygienic value and the general quality of the wine itself increase; the highest tasting scores were given to wine samples from the variants of treating grapes with foliar preparations from the group of biologically active substances: Chlorella algae extract and Biodux.

Effect of Yeast Concentration on Quality Parameters of Ber (Ziziphus mauritiana) Fruit (cv. Umran) Wine during Ageing

The present investigation was carried on for production of ber wine using yeast (Saccharomyces cerevisiae var. ellipsoideus) for fermentation. The quality parameters of ber wine were predicted by Design-Expert 7.7.0 software for optimizing the process parameters. The results obtained at T4 treatment (5 % inoculum) were encouraging with TSS (7.61 Brix), pH (4.06), residual reducing sugars (5.22 %) and alcohol (10.92 %) on 0th day of ageing with desirability factor of 0.95 followed by the results obtained on 90th day of ageing for T4 treatment (5 % inoculum) were TSS (6.27 °Brix), pH (4.22), residual reducing sugars (4.71 %) and alcohol content (12.07 %) with desirability factor of 0.93.

Study on quality parameters of wine at opening and deterioration with time

Wine is an alcoholic beverage made from grapes containing alcohol ranging from 5-15% by volume. Wine consumption in the Nepalese market is gaining steady growth in recent years. In this study, parameters such as specific gravity, total acidity, pH, percentage of alcohol content, amount of total dissolved solid, presence of furfural, methyl alcohol and heavy metal were selected for analysis of red and white wine with time after the opening of the packet wine at the time interval of 15, 20 and 25 days respectively. An increase in acidity and specific gravity (0.9780-0.9992 g/mL) while decrease in alcohol content (9.54%-8.03% by volume), presence of heavy Iron and Copper found below 0.003 and absence of furfural and methyl alcohol were observed with time. Consumption of wine in controlled amounts could prevent heart disease and circulatory problem. However, excess wine consumption can inhibit new brain cell development and depressive disorders.

Microbial diversity on grape epidermis and wine volatile aroma in spontaneous fermentation comprehensively driven by geography, subregion, and variety

On their journey from the wine grape to the resulting wine, microbiota from grape surfaces controlled by multiple factors is transferred to wine spontaneous fermentation process with indisputable consequences for wine quality parameters. The associated microbiota was regionally distinct (defined to microbial terroir) but how these microbial patterns with significantly regional distinctiveness quantitatively drive the wine regional characteristics are not definite within a complete grape ecosystem at different geographical (> 300 km), subregional (< 10 km), and varietal scales. Here, we collected 24 samples (containing two grape varieties) from four subregions of two regions in Xinjiang wine production area to investigate fungal distribution patterns and the association with wine chemical composition at different evaluation scales. Meanwhile, the relationships were established between geographical, subregional, varietal community of fungi, and wine volatile aroma using partial least squares regression (PLSR) and structural equation modeling (SEM). Results show that microbial and volatile samples present the significantly regional difference inside the complete ecosystem. Microbiota showed a stronger heterogeneity at geography scales, which drove the distributions of subregional and varietal microbiota thereby influencing the volatile composition of finished wines. Moreover, geographical microbiota seems to weaken the effects of varietal community on wine aroma compounds. Microbial communities respond to environmental changes within a completely set grape-related ecosystem at different scales, and these responses resulted in the wine regional distinctiveness based on the volatile profiles. Our findings further confirmed the important role of microbial terroir in shaping wine styles and provided the new cerebration for the terroir drivers of microbiota.

Influence of non-irrigation and seasonality on wine colour, phenolic composition and sensory quality of a grapevine (&lt;i&gt;Vitis vinifera&lt;/i&gt; cv. Callet) in a Mediterranean climate

Most vineyards in Mediterranean areas are cultivated using a training system and drip irrigation. However, the increasing risk of water deficit stress due to global warming will mean that viticulture need to adapt to a tougher water-saving policy. Thus, we investigated the effects of total suppression of irrigation on a grapevine (Vitis vinifera cv. Callet) and the phenolic composition and sensory quality of this native red variety wine from the Balearic Islands over three seasons. Significant yield reductions of up to 15.6 %, 17.2 % and 22.2 % were observed in non-irrigated (NI) plants in 2016, 2017 and 2018 respectively, compared to irrigated plants (I); however, wine quality parameters improved. In the years with the highest rainfall (715 mm in 2016 and 799 mm in 2017), NI favoured the enrichment of sugars, anthocyanins and phenolic compounds in the wine and enhanced the development of aromatic components. However, with lower rainfall (524 mm in 2018), the NI treatment appeared to diminish the quality of the wine, particularly affecting the global sensory quality of the wines. Thus, development of specific water strategies tailored to the vineyard, year, vintage and grape variety may regulate the phenolic composition of red wines to meet production goals and reduce total water consumption.

Examination of the most important red wine grape varieties of the Miniş (Ménes) wine region based on their quantitative and qualitative parameters

Abstract Winemaking has a very old history, which goes back thousands of years in the past. Numerous countries and geographical regions are known and acknowledged for their winemaking history. In Romania, there are countless winemaking regions that produce high-quality red and white wines. In the present experiment, we measured the quantitative and qualitative parameters of two red wines manufactured from worldwide-known varieties (Cabernet Sauvignon and Merlot) and two red wines produced from traditional grape varieties (Cadarcă/Kadarka and Fetească Neagră/Fekete Leányka). The data were collected in three different years to see if the traditional varieties could compete with the worldwide-known varieties. In terms of wine quality parameters, looking at total acidity, the Cabernet Sauvignon in 2018 while in terms of alcohol content the Fetească Neagră/Fekete Leányka in 2017 showed the highest values. From the sensory examination, it could be concluded that Fetească Neagră/Fekete Leányka yielded the best results in 2017, in 2018 the Cadarcă/Kadarka, and in 2019 the Merlot variety.

Forever Young? Late Shoot Pruning Affects Phenological Development, Physiology, Yield and Wine Quality of Vitis vinifera cv. Malbec

‘Malbec’ grapevines commonly have high yield, thus intermittently negatively affecting wine quality parameters. Here, we describe the use of late shoot pruning (LSP) practice applied for wine quality improvement. We examined the effect of timing of LSP on ‘Malbec’ vines grown in Mediterranean conditions during three consecutive seasons (2016–2018) in Israel. The timing of LSP treatment applications (applied one, two and three weeks after bud break) were compared with cluster-thinned, winter-pruned vines (WP + T) and standard winter pruning (WP). The LSP practice postponed bud break of target buds but did not have a temporal effect on the onset of veraison. Midday stem water potential was less negative and stomatal conductance and net CO2 assimilation rate were higher in the LSP vines. This practice led to a substantial reduction in the number of clusters and crop yield. Finally, wine quality was positively affected by applying LSP treatment. Performing the inexpensive LSP treatment at the precise timing after bud burst was found to save labor, decrease crop yield and improve grape and wine parameters. LSP application should be considered in adequate varieties as a significant tool for the enhanced effectiveness of vine growing in warm regions.

Impact ofBotrytis cinerea‐infected grapes on quality parameters of red wine made from withered grapes

Background and Aims Modification of important odorants induced by Botrytis cinerea has been reported in dry red wine (Amarone) made from withered grapes, but the impact on wines produced in other regions remains to be elucidated. Methods and Results Cabernet Franc grapes from Ontario were dried to 28.0°Brix and fermented with either non-botrytised grapes or a combination of non-botrytised and botrytised grapes (10% infection). The metabolites, including volatile compounds, were analysed and sensory evaluation including consumer preference were assessed. Gluconic acid, glycerol and acetic acid were significantly higher in the B. cinerea wines. Differences in some ethyl esters, isoamyl acetate and hexanol were observed between the Control and botrytised wines. These wines were differentiated by only one sensory attribute. A consumer preference test (n = 153) comparing liking scores of wines from this study to wines previously made from withered grapes fermented with an autochthonous yeast showed no difference in preference. Conclusions Inclusion of 10% B. cinerea infection in wines vinified from withered Cabernet Franc grapes makes little chemical or sensory difference, suggesting culling at this infection rate may be unnecessary and does not negatively impact consumer liking. Significance of the Study Red wine made from withered grapes may tolerate 10% botrytised fruit without adversely affecting consumer liking.

Pre-processing Cooling of Harvested Grapes Induces Changes in Berry Composition and Metabolism, and Affects Quality and Aroma Traits of the Resulting Wine.

Due to the greenhouse gas increase, grapes are often exposed to high temperatures in several growing areas especially during the final developmental stages, and this is particularly true when early ripening cultivars are harvested. This may cause undesirable effects on berry metabolism and composition and wine quality, particularly concerning the aroma profile. Harvesting at night or keeping the harvested grapes in cold rooms before vinification are empirical protocols applied in specific viticultural areas. To study the effects of decreasing berry temperature after harvest, white-skinned berries (cv Vermentino) were maintained at 4 or 10°C for 24 or 48 h before processing (pre-cooling). Control grapes were kept at 22°C. Grapes cooled at 10°C for 24 and 48 h resulted richer in polyphenols and showed a significant up-regulation of genes involved in polyphenols biosynthesis (i.e., VvPAL, VvSTS2, and VvFLS1). Similar behavior was observed in samples kept at 4°C for 48 h. Pre-cooling induced specific changes in the volatile organic compound (VOC) profiles. In particular, higher amounts of a specific subcategory of terpenes, namely sesquiterpenes, were detected in cooled samples. The induction of the expression of key genes involved in terpenoids biosynthesis (VvHDR, VvDX3, VvTER, VvGT14) was detected in cooled grapes, with variable effects depending on temperature and treatment duration. In both cooled samples, the evolution of alcoholic fermentation followed a regular trend but ended earlier. Higher phenolic content was detected in wines obtained from the 10°C-treated grapes. Higher residual concentration of malic acid at the end of fermentation was detected in wine samples from grapes pre-cooled at 4°C. Sesquiterpenes also showed a general increase in wines from cooled grapes, especially after pre-cooling at 10°C for 48 h. Different sensory profiles characterized the wine samples, with the best scores in terms of general pleasantness obtained by the wine produced from grapes pre-cooled at 4°C for 24 h. These results demonstrate that pre-cooling harvested grapes induces specific effect on the VOC profile and other quality parameters of Vermentino wine, and this appears to be the result of specific metabolic and compositional changes occurring in the berries.

Non-Thermal High Pressure Processing, Pulsed Electric Fields and Ultrasound Preservation of Five Different Table Wines

Wine preservation by alternative non-thermal and physical methods including high pressure processing (HPP), pulsed electric fields (PEF) and power ultrasound (US) technologies was investigated. The effect of these technologies on some quality parameters of five table wines was determined directly after processing and two months storage. For each wine, the pH, colour density, total phenolic content and antioxidant activity quality parameters were determined and the different treatments were compared. The pH of the untreated and treated wines generally remained unchanged after processing and storage. The antioxidant activity of the wines decreased after processing and storage. Generally, non-thermal processing did not affect the wine quality parameters during the 2 months storage. Overall, this study demonstrated that HPP had the smallest effect on the quality parameters assessed in five different wines.

The influence of selected indigenous yeasts on Pinot Noir wine colour properties.

The use of indigenous selected starters in winemaking is gaining interest due to certain advantages for the sensory quality of the wine. The present work shows the results of a laboratory experiment in which the influence of selected indigenous yeasts on the colour characteristics of Pinot Noir was studied with the use of high hydroxycinnamate decarboxylase activity yeasts. Pichia guilliermondii ZIM624 and Wickerhamomyces anomalus S138 yeasts were used in sequential fermentation with two strains of Saccharomyces cerevisiae, the native ZIM2180 strain and commercial Fermol Premier Cru (FPC). In co-inoculation fermentations, non-Saccharomyces yeasts decreased colour intensity (on average by 25.5%). In wines fermented with ZIM624, the concentration of vinylphenolic pyranoanthocyanins increased (average concentration 1.5mg L-1 ). However, vitisin concentration was significantly higher in S138 + FPC fermentation (1.3mg L-1 and an average of 0.9mg L-1 , respectively). Pinot Noir wines fermented with only ZIM2180 and sequential inoculation of ZIM624 + ZIM2180 resulted in significantly higher colour intensity (6.1± 0.0AU and 4.4± 0.0AU, respectively) and lower wine hue parameters compared to other wines. Sensory evaluation also showed that both wines had the highest perceived colour intensity and purple colour suggesting improvement in wine quality parameters. The results confirmed that selected indigenous starters made out of Saccharomyces and non-Saccharomyces yeasts can alter Pinot Noir wine colour parameters and improve wine colour properties. Those yeasts properties should be investigated prior to the development of new commercial starters but also be considered in large scale spontaneous fermentations of low colour intensity red wines like Pinot Noir. © 2021 Society of Chemical Industry.

Water stress assessment on grapevines by using classification and regression trees.

Multiple factors, such as the vineyard environment and winemaking practices, are known to affect the development of vines as well as the final composition of grapes. Water stress promotes the synthesis of phenols and is associated with grape quality as long as it does not inhibit production. To identify the key parameters for managing water stress and grape quality, multivariate statistical analysis is essential. Classification and regression trees are methods for constructing prediction models from data, especially when data are complex and when constructing a single global model is difficult and models are challenging to interpret. The models were obtained by recursively partitioning the data space and fitting a simple prediction model within each partition. The partitioning can be represented graphically as a decision tree. This approach permitted the most decisive variables for predicting the most vulnerable vineyards and wine quality parameters associated with water stress. In Priorat AOC, Carignan grapevines had the highest water potential and abscisic acid concentration in the early growth plant stages and permitted vineyards to be classified by mesoclimate. This information is useful for identifying which measurements could most easily differentiate between early and late‐ripening vineyards. LWP and Ts during an early physiological stage (pea size) permitted warm and cold areas to be differentiated.

Impacts of Pre-bloom Leaf Removal on Wine Grape Production and Quality Parameters: A Systematic Review and Meta-Analysis

Wine grape (Vitis vinifera L.) is the most widely cultivated fruit crop in the world. However, the climactic characteristics in some growing regions are suboptimal for grape production, including short season length and excess precipitation. Grape growers can utilize an array of methods to mitigate these issues, including “early leaf removal,” a management practice involving the removal of leaves from selected basal nodes along shoots around bloom. This meta-analysis reviews the extensive literature on this practice, with specific regards to application at “pre-bloom” (PB). One hundred seventy-five publications on the topic of “early leaf removal” were identified using key terms and subsequently narrowed via eight data curation steps. The comparison between treated (PB) and control plants in these studies revealed two important results. First, PB lowered bunch rot disease (−61%), partially through reducing the compactness of clusters. Second, PB promoted a significant increase in fruit total soluble solids (°Brix, +5.2%), which was related to the increase in the leaf-to-fruit ratio. Furthermore, cultivar and rootstock were found to have a large influence on the success of PB, while the contribution of climate was smaller. In conclusion, PB significantly lowers yield and bunch rot disease and increases °Brix, both of which improve grape and wine quality.

High Potential of Pichia kluyveri and Other Pichia Species in Wine Technology.

The surfaces of grapes are covered by different yeast species that are important in the first stages of the fermentation process. In recent years, non-Saccharomyces yeasts such as Torulaspora delbrueckii, Lachancea thermotolerans, Metschnikowia pulcherrima, and Pichia kluyveri have become popular with regard to winemaking and improved wine quality. For that reason, several manufacturers started to offer commercially available strains of these non-Saccharomyces species. P. kluyveri stands out, mainly due to its contribution to wine aroma, glycerol, ethanol yield, and killer factor. The metabolism of the yeast allows it to increase volatile molecules such as esters and varietal thiols (aroma-active compounds), which increase the quality of specific varietal wines or neutral ones. It is considered a low- or non-fermentative yeast, so subsequent inoculation of a more fermentative yeast such as Saccharomyces cerevisiae is indispensable to achieve a proper fermented alcohol. The impact of P. kluyveri is not limited to the grape wine industry; it has also been successfully employed in beer, cider, durian, and tequila fermentation, among others, acting as a promising tool in those fermentation processes. Although no Pichia species other than P. kluyveri is available in the regular market, several recent scientific studies show interesting improvements in some wine quality parameters such as aroma, polysaccharides, acid management, and color stability. This could motivate yeast manufacturers to develop products based on those species in the near future.

Rapid prediction of multiple wine quality parameters using infrared spectroscopy coupling with chemometric methods

Infrared spectroscopy (IRs) coupling with chemometric methods were used to predict principal quality parameters in wine. A new strategy of variable (wavelength) selection named as Fisher Discriminant-Variable Selection (FD-VS) model was constructed. Characteristic variables were selected from Infrared spectra based on the absolute values of eigenvector obtained by Fisher Discriminant Function. The FD-VS method was combined with quantitative models including Principal Component Regression (PCR), Partial Least Squares (PLS) and Least Squares Support Vector Regression (LSSVR), which were utilized for prediction of multiple principal quality parameters of red wine. It is shown that FD-VS method obviously improves the performances of PCR, PLS and LSSVR models. Then four variable selection methods based on PLS regression including Competitive Adaptive Reweighted Sampling (CARS)-PLS, Uninformative Variable Elimination (UVE)-PLS, Interval Partial Least Squares (IPLS) and Moving Windows Partial Least Squares (MWPLS) were also compared. The results also show good performance of FD-VS-LSSVR in terms of prediction accuracy or robustness. Therefore, the FD-VS method provides an effective and credible variable selection way for IR spectrum to predict quality parameters of wine.

Substitution or Dilution? Assessing Pre-fermentative Water Implementation to Produce Lower Alcohol Shiraz Wines.

Changes to regulations by Food Standards Australia New Zealand have permitted the adjustment of must sugar levels with the addition of water in order to ensure a sound fermentation progress as well as mitigating excessive wine–alcohol levels. This study assessed the implications for Shiraz wine quality following a pre-fermentative must dilution (changing liquid-to-solid ratios), in comparison to juice substitution with water (constant liquid-to-solid ratios) that has previously been deemed a promising way to adjust wine–alcohol levels. While working within the legal limit of water addition to grape must, the effects of both approaches on wine quality parameters and sensory characteristics were rather similar, and of negligible nature. However, different implications between substitution and dilution appeared to be driven by grape maturity, and dilution was found to have a greater impact than substitution on some parameters at higher water implementation rates. In line with previous observations, longer hang-time followed by alcohol adjustments via pre-fermentation water addition were of limited merit compared to simply picking grapes earlier. This work provided further knowledge that supports informed decision making regarding the recently permitted approach of using water during winemaking.