The role of processing on ochratoxin A content in Italian must and wine: a study on naturally contaminated grapes

Available data show that ochratoxin A (OTA) is a possible contaminant of wine and its concentration is higher in red wines than in white and rosé. The aim of this work was to study the fate of OTA during the main stages of the winemaking process (crushing, maceration, alcoholic fermentation, malo-lactic fermentation, bottle-aging) and the influence of technological treatments on OTA concentration in order to identify the critical process steps. Attention was focused on red winemaking, in different wineries in the south of Italy, with two naturally OTA contaminated grape varieties ('Negroamaro' and 'Primitivo') and on different vintages (2001-2002-2003). The results show that no OTA is produced during winemaking, but each operation during winemaking can modify OTA content. The OTA present in grapes to a certain degree is released to the juice during crushing. Maceration increases the OTA content, while alcoholic and malo-lactic fermentation cause a reduction in OTA in the wine.     

Degradation of white wine haze proteins by Aspergillopepsin I and II during juice flash pasteurization

Bentonite is commonly used to remove grape proteins responsible for haze formation in white wines. Proteases potentially represent an alternative to bentonite, but so far none has shown satisfactory activity under winemaking conditions. A promising candidate is AGP, a mixture of Aspergillopepsins I and II.; a food grade, well characterized and inexpensive protease, active at wine pH and at high temperatures (60-80°C). AGP was added to two clarified grape juices with and without heat treatments (75°C, 1min) prior to fermentation. AGP showed some activity at fermentation temperatures (≈20% total protein reduction compared to control wine) and excellent activity when combined with juice heating (≈90% total protein reduction). The more heat stable grape proteins, i.e. those not contributing to wine hazing, were not affected by the treatments and therefore accounted for the remaining 10% of protein still in solution after the treatments. The main physicochemical parameters and sensorial characteristics of wines produced with AGP were not different from controls.     

Evaluation of pathogenesis-related protein content and protein instability of seven white grape (<Emphasis Type="Italic">Vitis vinifera</Emphasis> L.) clones from Casablanca Valley,Chile

Thaumatin-like proteins and chitinases are the main pathogenesis-related (PR) proteins found in grapes, grape juice and wine and are responsible for protein haze formation in bottled white wine during storage and transport. We have studied the effect of the content of both thaumatin-like proteins and chitinases on protein instability of Sauvignon blanc (clones 1, 107 and 242) and Chardonnay (clones 4, 5, 75 and Mendoza) grape juices from both a warm and a cold production zone in the Casablanca Valley, Chile. The PR proteins were identified and quantified by reversed-phase liquid chromatography (RP-HPLC). Protein instability was determined using a heat test and was expressed in nephelometric turbidity units (NTUs). Thaumatin-like (TL) proteins were identified as the major PR proteins present in all grape juices studied. Three TL proteins were identified and named Vitis vinifera thaumatin-like proteins 1, 2 and 3 (VVTL1, VVTL2 and VVTL3). Chitinase A (ChitA) was identified in the Sauvignon blanc and Chardonnay grape juices, and chitinase B (ChitB) was found only in Chardonnay grape juices. Significant differences in the protein content and in the type of protein were observed between grapes from different production zones and between grapes of different varieties, respectively.     

Evaluating the Influence of Malolactic Fermentation Inoculation Practices and Ageing on Lees on Biogenic Amine Production in Wine

Biogenic amines are compounds, produced primarily by lactic acid bacteria (LAB) that negatively affect the wholesomeness of wine. Standard winemaking practices can greatly influence the levels of biogenic amines in wine. The aim of this study was to determine the relative contribution of different malolactic fermentation (MLF) practices and ageing of wines on fermentation lees to the final levels of biogenic amines. Wines were made on small scale over two harvest seasons with two red grape cultivars. Treatments included spontaneous MLF, co-inoculated MLF, MLF inoculated after alcoholic fermentation (conventional inoculation) and 4 months of ageing in the presence and absence of fermentation lees of all MLF treatments. Biogenic amine concentrations were measured by high-performance liquid chromatography at key winemaking stages and statistically analysed for the effects of MLF treatment and winemaking stage. Results indicate that the presence of indigenous LAB increased the risk of biogenic amine formation. Inoculation proved to reduce biogenic amine production over time compared to spontaneous MLF and co-inoculation even more than conventional inoculation. The presence of yeast lees during ageing generally led to higher final concentrations of biogenic amines in wines than the absence of lees. This study confirms other works that conclude that spontaneous MLF and uncontrolled ageing on yeast lees are generally unpredictable and pose a risk of biogenic amine contamination in finished wines.     

Volatile composition of Bobal red wines subjected to alcoholic/malolactic fermentation with oak chips

The effect of wood, in the form of oak chips, on the volatile composition of Bobal red wines caused by adding oak chips at different stages of the fermentation process has been studied. Aroma compounds were isolated by solid phase extraction (SPE) for subsequent analysis by gas chromatography–mass spectrometry (GC/MS). Bobal control wine was produced according to traditional winemaking processes, without oak chips. Oak chips were added to the rest of the wines at two dose levels (3 and 6 g/L) at different stages of the winemaking process: at one week during alcoholic fermentation (AF), during malolactic fermentation (MLF) and in young, red Bobal wine. Wines fermented with oak chips during AF showed higher concentrations of the ethyl esters of straight-chain fatty acids and ethyl, hexyl and isoamyl acetates than the control wine. A similar, trend was observed for higher alcohols. Higher concentrations of benzene compounds, oak lactones and furanic compounds were found in wines in contact with oak chips during MLF followed by young Bobal oak wines. These results reveal that the point of addition during the winemaking process and the dose level of oak chips used have a significant effect on the volatile composition of Bobal red wines.     

葡萄酒及葡萄皮渣提取物抑制乙酰胆碱酯酶活性研究

建立乙酰胆碱酯酶抑制剂体外筛选模型,对不同的葡萄酒及葡萄皮渣提取物等19种样品进行了乙酰胆碱酯酶活性抑制作用的研究。结果显示白葡萄酒几乎无乙酰胆碱酯酶抑制活性,红葡萄酒对乙酰胆碱酯酶具有不同的抑制活性,抑制率最高为山葡萄酒,其抑制率为11.12%。葡萄皮渣的水、乙醇、乙酸乙酯提取物,具有抑制乙酰胆碱酯酶活性,其抑制率分别为3.91%、18.25%、20.76%,乙酸乙酯提取物的抑制效果最好。红葡萄酒和葡萄皮渣的乙酸乙酯提取物可作为辅助治疗阿尔茨海默病的先导化合物进行深入研究。     

Optimal Conditions for Controlling Haze-Forming Wine Protein with Bentonite Treatment: Investigation of Matrix Effects and Interactions Using a Factorial Design

Protein instability in white wine can result in unsightly haze formation, and therefore, its prevention by adsorption of haze proteins onto bentonite is an important unit operation in commercial wine production. Optimisation of this process is challenging due to the performance impact of environmental factors and matrix effects which are difficult to control and study in wine systems. These issues are addressed in the present study; the effect of different factors on adsorption behaviour of a purified thaumatin-like grape protein (VVTL1) by sodium bentonite in a chemically defined model wine solution was investigated using a factorial design with surface response analysis. Bentonite adsorption of VVTL1 was well characterised by a multi-factor Langmuir adsorption model. The main effects of pH, temperature, potassium concentration as well as the pH*potassium matrix interaction all had a significant effect (p?<?0.05) on the adsorption capacity, as did the aging of bentonite slurry before use. Observations support the hypothesis that VVTL1 adsorption onto sodium bentonite is affected by steric mass action and local interactions of exposed protein charge, with pH and temperature effects related to changes in protein conformation under those conditions. Variation in potassium concentration can cause similar effects and influence adsorption capacity by affecting bentonite swelling and charge potential, providing a greater surface area for adsorption. From a processing perspective, results suggest bentonite treatment efficiency will be optimised by treating wines at higher temperatures rather than during cold storage, at the lower pH and before cold (tartrate) stabilisation.     

Biogenic amines in wines: Influence of oenological factors

Biogenic amines formation results from the decarboxylation of the corresponding amino acids by action of microorganisms. The presence of these compounds is considered by some authors a fundamental parameter for detriment of alcoholic beverages. The aim of this work was to assay the effect of some oenological factors (viticulture region, grape variety, anti-fungi treatment of grapes, fermentation activators, malolactic starters and storage on lees) from the point of view of their influence on the biogenic amines content of wines. According to our results, it was possible to show that the viticulture region affects the amounts of amines, since wines of some regions present higher contents of amines than wines from other regions. Grape varieties appear to influence the wine amines content. Commercial malolactic starters, after careful selection, should be added to the vinification process in order to decrease the formation of biogenic amines, since in our assays the wines that were inoculated with starters present lower amounts of biogenic amines. The wine storage on lees contributes for a biogenic amines increase.     

Biogenic mono-, di- and polyamine contents in Spanish wines and influence of a limited irrigation

The distribution of biogenic aromatic amines, and also those of aliphatic diamines and polyamines, in red and white Spanish wines, was examined. Moreover, a study was carried out to determine whether the degree of irrigation affects the endogenous amine contents in grape as well as its evolution during the winemaking process. Amine levels were variable, ranging from not detected to 100 mg/l. Putrescine, which constituted the major amine, tyramine and histamine contents were significantly higher in red than in white wine. The aromatic phenylethylamine, and the aliphatic cadaverine, agmatine, spermine and spermidine, were detected in very low amounts in a few samples. Both, diamines and polyamines, were the only amines observed in grape samples, showing similar levels, irrespective of the water-stress degree, and their levels decreased significantly during winemaking. Most probably, the low levels of di- and polyamines in wine arise from those endogenously found in grape berries and the water-stress does not seem to be a factor influencing the contents.     

The historical geographies of growing and fermenting the Delaware grape in the Kōfu Basin of Yamanashi Prefecture,Japan

The Kōfu Basin in Yamanashi Prefecture is at the center of table grape and wine production in Japan. This article traces the historical geographies of the growing and fermentation of Delaware grapes in this region. Data were gathered from over 145 interviews with stakeholders across the table grape and wine industries, extensive archival research and participant observation as a grape farmer in the Kōfu Basin for over one and a half years. Emphasis is placed on intertwining that history to overarching developments in local viticulture and winemaking. This includes tracing the arrival of the cultivar from the USA to Japan at the start of the Meiji Restoration in 1868, early fermentation and later rapid diffusion linked to its popularity as the first commercially available seedless cultivar. Delaware reached the pinnacle of its popularity as a grape for the table and wine in the 1960s and 1970s, before changes in consumer demands to higher value table grapes and away from sweet wines led to its fairly rapid decline. Although significantly less Delaware is grown or fermented today, this introduced grape was and surprisingly continues to be highly influential on the developmental trajectories of Japanese grape growing and winemaking.     

Protein removal from a Chardonnay juice by addition of carrageenan and pectin

Backgrounds and Aims: Bentonite is commonly added to white wines to remove the grape proteins responsible for haze formation. Despite being effective, this technique has drawbacks; thus, new solutions are desirable. The ability of carrageenan and pectin to remove heat‐unstable grape proteins, and the impact that such addition has on the physicochemical and sensorial profile of a wine were assessed. Methods and Results: Carrageenan and pectin were added separately or in combination to a Chardonnay juice prior to fermentation. Both adsorbents removed proteins (up to 75%), thus increasing wine protein stability. Carrageenan was more effective than pectin at increasing wine protein stability. Conclusions: Pectin and carrageenan removed protein and partially stabilized the samples of the wine. Significance of the Study: Pre‐fermentation addition of pectin or carrageenan may provide the wine industry with an alternative protein stabilization procedure.     

Production of white wine by Saccharomyces cerevisiae immobilized on grape pomace

White wine was produced with Saccharomyces cerevisiae cells immobilized on grape pomace, by natural adsorption. The support, the main solid waste from the wine industry, consisted of the skins, seeds and stems. Immobilization was tested using different media, namely complex culture medium, raw grape must and diluted grape must. Grape pomace was revealed to be an appropriate support for yeast cell immobilization. Moreover, grape must was shown to be the most suitable medium as immobilized cells became adapted to the conditions in the subsequent alcoholic fermentation in the wine‐making process. The wines produced, either with immobilized cells or with free cells, were subjected to chemical analysis by HPLC (ethanol, glycerol, sugars and organic acids) and by gas chromatography (major and minor volatile compounds); additionally, colour (CIELab) and sensory analysis were performed. The use of immobilized systems to conduct alcoholic fermentation in white wine production proved to be a more rapid and a more efficient process, especially when large amounts of SO₂ were present in the must. Furthermore, the final wines obtained with immobilized cells demonstrated improved sensory properties related to the larger amounts of ethanol and volatile compounds produced. The more intense colour of these wines could be a drawback, which could be hindered by the reutilization of the biocatalyst in successive fermentations. Copyright © 2012 The Institute of Brewing & Distilling     

Application of molecular methods to demonstrate species and strain evolution of acetic acid bacteria population during wine production

The growth of acetic acid bacteria on grapes or throughout the winemaking process influences the quality of wine, mainly because it increases the volatile acidity. The objective of this study was to analyse how the acetic acid bacteria population evolves in the changing environment of the grape surface and during wine fermentation. We have analysed the influence of yeast inoculation and SO2 addition on acetic acid bacteria populations. These bacteria were analysed at both the species and the strain level by molecular methods such as Restriction Fragment Length Polimorfism (RFLP) of amplified 16S rDNA, and amplification by polymerase chain reaction of Enterobacterial Repetitive Intergenic Consensus (ERIC-PCR) and Repetitive Extragenic Palindromic (REP-PCR). Our results show that the increases in population size are normally accompanied by a proliferation of Acetobacter aceti, which is the main species during fermentation. The diversity of strains is considerable in natural environments such as the grape surface. Changes in the environment during alcoholic fermentation substantially reduce the survival and the diversity of acetic acid bacteria. Few strains are able to survive these conditions and they seem to originate from both the grapes and the winery. To the best of our knowledge this is the first time that acetic acid bacteria are analysed at the strain level in grape surfaces and during winemaking.     

Winemaking biochemistry and microbiology: current knowledge and future trends

The fermentation of grape must and the production of premium quality wines are a complex biochemical process that involves the interactions of enzymes from many different microbial species, but mainly yeasts and lactic acid bacteria. Yeasts are predominant in wine and carry out the alcoholic fermentation, while lactic acid bacteria are responsible for malolactic fermentation. Moreover, several optional winemaking techniques involve the use of technical enzyme preparations. Considerable progress has been made recently in understanding the biochemistry and interactions of enzymes during the winemaking process. In this study, some of these recent contributions in the biochemistry of winemaking are reviewed. This article intends to provide an updated overview (including works published until December, 2003) on the main biochemical and microbiological contributions of the different techniques that can be used in winemaking. As well as considering the transformations that take place in traditional winemaking, the production of special wines, such as sparkling wines, 'sur lie' wines, and biologically aged wines, are also studied.     

Engineering volatile thiol release in Saccharomyces cerevisiae for improved wine aroma

Volatile thiols, such as 4-mercapto-4-methylpentan-2-one (4MMP), 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA), are among the most potent aroma compounds found in wine and can have a significant effect on wine quality and consumer preferences. At optimal concentrations in wine, these compounds impart flavours of passionfruit, grapefruit, gooseberry, blackcurrant, lychee, guava and box hedge. The enzymatic release of aromatic thiols from grape-derived, non-volatile cysteinylated precursors (Cys-4MMP and Cys-3MH) and the further modification thereof (conversion of 3MH into 3MHA) during fermentation, enhance the varietal characters of wines such as Sauvignon Blanc. Wine yeast strains have limited and varying capacities to produce aroma-enhancing thiols from their non-volatile counterparts in grape juice. Even under optimal fermentation conditions, the most efficient thiol-releasing Saccharomyces cerevisiae wine strain known realizes less than 5% of the thiol-related flavour potential of grape juice. The objective of this study was to develop a wine yeast able to unleash the untapped thiol aromas in grape juice during winemaking. To achieve this goal, the Escherichia coli tnaA gene, encoding a tryptophanase with strong cysteine-beta-lyase activity, was cloned and overexpressed in a commercial wine yeast strain under the control of the regulatory sequences of the yeast phosphoglycerate kinase I gene (PGK1). This modified strain expressing carbon-sulphur lyase activity released up to 25 times more 4MMP and 3MH in model ferments than the control host strain. Wines produced with the engineered strain displayed an intense passionfruit aroma. This yeast offers the potential to enhance the varietal aromas of wines to predetermined market specifications.     

Application of high‐power ultrasounds during red wine vinification

Wine colour is one of the main organoleptic characteristics influencing its quality. It is of special interest in red vinifications due to the economic resources that wineries have to invest for the extraction of the phenolic compounds responsible for wine colour, compounds that are mainly located inside the skin cell vacuoles, where the volatile compounds are also found. The transfer of phenolic compounds from grapes to must during vinification is closely related to the type of grapes and the winemaking technique. During traditional winemaking, grapes are crushed and skin macerated for several days, with pumps overs to facilitate the colour extraction. To increase this extraction, some chemical (maceration enzymes) or physical technologies (thermovinification, cryomaceration, flash‐expansion) can be applied. In this work, a new methodology has been tested. This methodology consists in the application of high‐power ultrasounds to crushed grapes to increase the extraction of phenolic compounds. Crushed grapes were treated with this non‐thermal technology and vinified, with 3, 6 and 8 days of skin maceration time, and the results were compared with a control vinification, where crushed grapes were not subjected to any treatment and were skin macerated during 8 days. The wine chromatic characteristics (determined spectrophotometrically) and the individual phenolic compounds (anthocyanins and tannins, determined by HPLC) were followed during the maceration period, at the end of alcoholic fermentation and after two months in bottle. Also, the wine volatile compounds were determined by GC‐MS. The wines made with ultrasound‐treated grapes showed differences with the control wine, especially regarding total phenol content and tannin content. The wines elaborated with sonicated grapes and with only three days of skin maceration time presented similar concentration of anthocyanins and twice the concentration of tannins than control wines elaborated with 8 days of skin maceration.     

Statistical optimization of ethanol fermentation parameters for processing local grape cultivars to wines

Grape juice from two local grape cultivars viz. Punjab MACS purple and H‐144 was subjected to prefermentation skin treatment. Ethanol fermentation w.r.t agitation rate, temperature, inoculum size, and nutrient supplementation were optimized using Triple M medium following response surface methodology (RSM). RSM results were numerically optimized keeping temperature “in range” for red wine and “low” for white wine which showed agitation rate of 80 ± 1 rpm for 24 hr, diammonium hydrogen orthophosphate supplementation @ 150 mg/100 ml, inoculum size of 6.1 and 6.5% (vol/vol), and fermentation temperature of 24.6 and 21 °C as optimum for ethanol fermentation of red and white wines, respectively. Optimized results were validated on grape juice of Punjab MACS purple and H‐144 cultivars that lead to 12.0 and 11.2 (%vol/vol) ethanol production, respectively. Gas chromatography mass spectrometry analysis revealed the presence of 41 volatile compounds in the form of phenols, alcohols, terpenes, esters, ketones, and amines that add to the nutraceutical and antioxidant value of the wines.

Practical applications

Present study provides the statistical optimized fermentation parameters for red and white wine production separately. Optimization of an efficient processing technology to produce local grape wines will help to reduce the price of wines so that they are available to common masses at affordable costs besides improving the economic status of grape growers in the state and providing valuable information to wine makers to establish winery under North Indian conditions. Use of synthetic grape juice (Triple M media; during off season of grapes) lead to optimization of ethanol fermentation parameters in two separate fashions considering fermentation temperature as key parameter. Gas chromatography mass spectrometry analysis showed the presence of flavonoids, terpenes, and esters increasing nutritive value of product, providing antioxidants to the consuming person.     

Preventing protein haze in bottled white wine

Slow denaturation of wine proteins is thought to lead to protein aggregation, flocculation into a hazy suspension and formation of precipitates. The majority of wine proteins responsible for haze are grape‐derived, have low isoelectric points and molecular weight. They are grape pathogenesis‐related (PR) proteins that are expressed throughout the ripening period post véraison, and are highly resistant to low pH and enzymatic or non‐enzymatic proteolysis. Protein levels in un‐fined white wine differ by variety and range up to 300 mg/L. Infection with some common grapevine pathogens or skin contact, such as occurs during transport of mechanically harvested fruit, results in enhanced concentrations of some PR proteins in juice and wine. Oenological control of protein instability is achieved through adsorption of wine proteins onto bentonite. The adsorption of proteins onto bentonite occurs within several minutes, suggesting that a continuous contacting process could be developed. The addition of proteolytic enzyme during short term heat exposure, to induce PR protein denaturation, showed promise as an alternative to bentonite fining. The addition of haze‐protective factors, yeast mannoproteins, to wines results in decreased particle size of haze, probably by competition with wine proteins for other non‐proteinaceous wine components required for the formation of large insoluble aggregations of protein. Other wine components likely to influence haze formation are ethanol concentration, pH, metal ions and phenolic compounds.