Impact of wine manufacturing practice on the occurrence of fining agents with allergenic potential

Proteinogenic wine fining agents are hidden allergens and could present a risk for consumers with allergies. Therefore, the European Parliament adopted Directive 2003/89/EC amending Directive 2000/13/EC to declare ingredients, contaminations and processing aids that are known to trigger allergic reactions. The Amendment Regulation (EU) 1266/2010 excluded the labelling of wines which are processed with hen’s egg and products thereof until 30 June 2012 to get more scientific findings. After 1 July 2012 wine fining agents have to be declared if above 0.25 mg l^–1 (Regulation (EU) 579/2012 in conjunction with article 120 g of Regulation (EU) 1234/2007). The Organisation International de la Vigne et du Vin (OIV) advises this limit of detection (LOD) for potential allergenic residues of proteins. Wine fining agents are processing aids and according to the wine producer’s knowledge will be removed after coagulation by filtration or other production steps. Due to lack of scientific data, residues of fining agents in the final product could not be excluded. In this risk assessment, highly sensitive ELISA methods for ovalbumin of known origin for wine have been developed. The objective was to investigate the presence of allergen residues in wine after certain technological treatments were applied to remove the wine fining agents. For all developed ELISA methods the LODs are in the low µg l^–1 range between 5 and 10 µg l^–1 fining agent, whereas the LOQ varies between 5 and 80 µg l^–1 fining agent. The results of the investigation of well-known wines and fining agents demonstrate that white wines fined with white or ovalbumin from hen’s egg could retain allergens. The use of certain technological procedures during wine processing leads to different results. In white wine, bentonite or sheet filtration followed by sterile filtration lead to wines containing no detectable amounts of ovalbumin. In red wine, especially the final sterile filtration removes the fining agents.     

Effects of fining agents on trans-resveratrol concentration in wine

Resveratrol has been identified as a wine component related to moderate wine consumption and a reduction in serum cholesterol levels. Processes such as wine fining that result in loss of resveratrol during winemaking are therefore of interest, and led to these present studies. A number of agents were compared and were found to lower resveratrol levels in all wines to some extent. Results from two studies (1996 and 1997) are reported. The standard addition method was used in combination with High Pressure Liquid Chromatography to calculate resveratrol levels. In Study 1 (1996), recommended maximum levels of all fining agents (Level 3), bentonite, egg white, gelatin + kieselsol and polyvinylpolypyrrolidone (PVPP), lowered resveratrol levels significantly compared to controls (Level 0). Nevertheless, addition of fining agents at Level 0 resulted in resveratrol levels that were significantly higher than those at Level 3, but resveratrol levels in wine from Level 0 were not significantly different from Level 1. In Study 2 (1997), carbon + egg white, and gelatin + kieselsol fining was studied, and their effects differed according to grape variety. Least removal of resveratrol by carbon fining occurred in wine from Cabernet Sauvignon (Vitis vinifera) whereas most removal occurred in wines from Cynthiana (Vitis aestivalis) and Noble (Vitis rotundifolia). Resveratrol levels of control wine were significantly higher than resveratrol levels of wine treated with recommended maximum addition of fining agent in all varieties. Taken overall, any addition of any fining agent lowered resveratrol levels in all wines to some extent, but complex interactions between fining agent and wine variety resulted in different regression trends. While recognising the constraints set by our particular data that could reflect unique circumstances, we are nevertheless able to infer from these trends that low levels of fining agents can be used without statistically significant loss of resveratrol.     

Ochratoxin A removal from red wine by several oenological fining agents: bentonite,egg albumin,allergen-free adsorbents,chitin and chitosan

The ability of several oenological fining agents to remove ochratoxin A (OTA) from red wine was studied. The adsorbents tested were activated sodium bentonite, egg albumin, allergen-free adsorbents (complex PVPP, plant protein and amorphous silica (complex) and high molecular weight gelatine), and the non-toxic biodegradable polymers (chitin and chitosan). Several dosages within the oenological use range were tested and the wine pH, colour parameters and polyphenol concentration impact associated with each fining agent were studied. Generally, OTA removal achieved in all treatments was higher when the adsorbent dosage increased, but the impact on wine quality also was higher. Chitin at 50?g?hl^?1 removed 18% the OTA without affecting significantly the wine-quality parameters. At the highest dosage tested the gelatine and complex treatments achieved greater OTA removal (up to 39–40%) compared with bentonite, egg albumin and chitin. Moreover, the gelatine and the complex had a lower impact on colour parameters and polyphenol concentration compared with chitosan, whilst OTA was reduced to around 40%. Chitosan achieved the greatest OTA removal (67%), but it strongly affected the wine-quality parameters. Otherwise, bentonite showed a relative efficiency to remove OTA, but the CI value decreased considerably. The egg albumin treatment only removed OTA up to 16% and moreover affected strongly the CI value and CIELab parameters. The results of this survey showed that the non-toxic chitin adsorbent and the allergen-free adsorbents tested could be considered as alternative fining agents to reduce OTA in red wine.     

Fermentation kinetics and chemical characterisation of vino tostado,a traditional sweet wine from Galicia (NW Spain)

BACKGROUND: Grapes after harvesting are air dried and pressed in order to concentrate sugars, acids and flavour compounds to produce vino tostado (toasted wine), a wine with intense aroma and flavour notes and high residual sugar concentration. In order to get a better knowledge of the difficulties involved, several fermentations were conducted at 12 and 28 °C using 0, 15 and 30 g hL^?1 ammonium sulfate and 0, 25 and 50 g hL^?1 exogenous commercial yeast (Saccharomyces cerevisiae var. bayanus) to study the kinetics of sugar consumption and ethanol, acetic acid and glycerol production. RESULTS: Fermentation kinetic parameters were calculated and metal concentrations and antioxidant activity were analysed. CONCLUSION: The spontaneous fermentation at 12 °C and all fermentations conducted with the commercial yeast gave vino tostado of adequate quality, while the spontaneous fermentation at 28 °C was sluggish. High‐temperature fermentations led to sweeter wines with higher volumetric productivities, although low‐temperature fermentations produced better wines in terms of higher glycerol and lower acetic acid levels. Fructose was the only sugar to be consumed during spontaneous fermentations, while both glucose and fructose were consumed during fermentations of the inoculated musts, with preference for each monosaccharide depending on temperature. Copyright © 2009 Society of Chemical Industry     

Effects of fining with different bentonite labels and doses on colloidal stability and colour of a Valpolicella red wine

This study addressed four different labels of activated sodium bentonite during the fining of a young Valpolicella red wine. Preliminary tests determined the bentonite dose (0.15, 0.30 or 0.50 g L^?1) that would achieve colloidal stability, and this dose was further applied during laboratory‐scale trials. The bentonites were characterised by physico‐chemical parameters, and the effects of the label and dose on the wine colloidal stability, proteins, colour indices and phenolic compounds were measured. The results demonstrated that 0.50 g L^?1 for every bentonite label provided colloidal stabilisation without harshly affecting the colour. Unlike to what happens in white wines the least charged bentonite labels were effective at stabilising the red wine colloidal state by partially reducing its protein content. Simultaneously, the most negatively charged clay samples determined the largest depletions on the total polyphenols, anthocyanins, tannins and polymeric pigments. The differentiated action of clays with different surface charge density among white and red wines may be explained by the interaction mediated by positively charged anthocyanins towards either protein or tannin depletion. Although pioneering, these results may move towards the definition of a safe, allergen‐free, and effective adjuvant for colloidal stabilisation targeted to wine type.     

Influence of some technological practices on the quantity of resveratrol in wine

A study of the effects of some prefermentative and fining practices on the resveratrol concentration in wine was carried out. The trans- and cis-resveratrol contents in a red wine obtained using must hyperoxidation were reduced to about 50% compared with those of control wines; this decrease was greater than that observed for total phenols and catechins. In contrast, sparging the red grapes with SO₂ and ascorbic acid before crushing them resulted in the trans-resveratrol concentration being greater than that of the control wines. Moreover the amounts of trans- and cis-resveratrol in commercial and synthetic wines were determined before and after addition of charcol, polyvinylpolypyrrolidone (PVPP), bentonite, casein, gelatine, and two inert materials, cellulose and diatomaceous earth (kieselgur), used as a filter aid. The results showed that PVPP, charcoal and casein were more effective at removing trans- and cis-resveratrol both in synthetic wine and in commercial wines. In all the wines tested the other fining agents gave a limited decrease (2?–?5%) of trans- and cis-resveratrol. After charcoal and PVPP treatments, significant correlations were observed between the percentage of residual resveratrol and the total phenols in the wines.     

Influence of some technological practices on the quantity of resveratrol in wine

 A study of the effects of some prefermentative and fining practices on the resveratrol concentration in wine was carried out. The trans- and cis-resveratrol contents in a red wine obtained using must hyperoxidation were reduced to about 50% compared with those of control wines; this decrease was greater than that observed for total phenols and catechins. In contrast, sparging the red grapes with SO₂ and ascorbic acid before crushing them resulted in the trans-resveratrol concentration being greater than that of the control wines. Moreover the amounts of trans- and cis-resveratrol in commercial and synthetic wines were determined before and after addition of charcol, polyvinylpolypyrrolidone (PVPP), bentonite, casein, gelatine, and two inert materials, cellulose and diatomaceous earth (kieselgur), used as a filter aid. The results showed that PVPP, charcoal and casein were more effective at removing trans- and cis-resveratrol both in synthetic wine and in commercial wines. In all the wines tested the other fining agents gave a limited decrease (2 – 5%) of trans- and cis-resveratrol. After charcoal and PVPP treatments, significant correlations were observed between the percentage of residual resveratrol and the total phenols in the wines. Received: 16 June 1997     

The use of thaumatin and bovine serum albumin as proteins in model wine solutions in bentonite fining

This study examined the viability of using thaumatin and bovine serum albumin (BSA) as proteins in model wine solutions for bentonite fining studies and compared them with unfined New Zealand sauvignon blanc (SB) wine. Bentonite fining trials were performed on model wine solutions and unfined SB wines (pH range 3.5–4.3). Thaumatin was more readily adsorbed onto bentonites of all types than BSA and its adsorption onto bentonite was less affected by the pH of the solution. Specifically, the amount of BSA adsorbed onto bentonite decreased significantly as the pH of the solution approached the isoelectric point (pI) of BSA while thaumatin was adsorbed at that pH due to its higher pI. Changing pH affected protein adsorption of real wine less noticeably than of BSA and thaumatin, and decreasing pH increased protein adsorption in contrast to the model solutions. Neither of the model solutions can fully represent the response of real wine to bentonite fining but they are simple and cost effective to prepare and reacted to changes in bentonite concentration similar to real wine. Thaumatin is potentially a better protein to use in simple model solutions for wine stabilisation studies like filtration where molecular weights are important consideration.     

Clarifying effect of different fining agents on mulberry wine

Fining experiments have been conducted on mulberry wine, in which five fining agents (bentonite, gelatin, casein, egg albumin and PVPP) were investigated. The effect of these agents on polyphenol content, colour intensity, antioxidant activity and aromatic profile has been determined. In general, all treatments improved the limpidity of the mulberry wines to some extent. The wine was mostly negatively affected by gelatin and led to the greatest reduction of phenol content (16.61%), colour intensity (32.26%) and antioxidant activity. Concerning aroma, the addition of PVPP, casein and bentonite both significantly altered the aroma profile. It is noteworthy that egg albumin led to the lowest diminution total phenol value (5.74%) and improvement of antioxidant capacity and colour among the tested fining agents. Furthermore, the aroma profile remained mostly unaffected by egg albumin. As consequence, the optimal fining agent for mulberry wine was egg albumin.     

Lysozyme in wine: A risk evaluation for consumers allergic to hen's egg

Lysozyme used in wine production could present a risk for consumers allergic to hen's egg. Thus, precautionary labeling of lysozyme on wines has been adopted within the European Community by updating Annex IIIa by Directive 2007/68/EC on November 27, 2007. Since no scientific data is known about the actual amounts and risks of lysozyme in wines, various in vitro efforts and skin prick tests were applied in this study to evaluate the presence of lysozyme in wines and the reactivity of those residues in allergic individuals and to fulfill the claim of updating Annex IIIa announced in Directive 2003/89/EC. Depending on the wine's color (red or white wine) and fining with bentonite, which is known as an important step to remove unstable proteins mainly from white wines, diverse results were obtained concerning the amounts of lysozyme in finished wines and their in vitro and in vivo reactivity in humans allergic to hen's egg.     

The effect of juice clarification, static or rotary fermentation and fining on ochratoxin A in wine

Semillon and Shiraz grapes containing ochratoxin A (OA) were produced by inoculation of bunches on the vine with Aspergillus carbonarius . Small scale vinification of these grapes was performed and the OA content at various stages was analysed. Semillon must was treated with pectolytic enzymes and the juice after pressing was fined with bentonite. Neither pectolytic enzymes nor bentonite influenced the OA content of the clarified juice. Shiraz must was vinified by either static or rotary fermentation. No differences in the OA content of wine after pressing were noted. OA was concentrated in juice lees and gross lees. However, additional juice or wine recovered from lees after centrifugation did not display increased OA contamination compared to racked juice or wine. Addition of bentonite at 2.5 g/L to a Semillon wine containing 56 mg grape-derived protein/L and ca. 8 μg OA/kg resulted in a 67% reduction in OA concentration. Potassium caseinate showed some effect, whereas gelatin, isinglass and PVPP did not significantly diminish OA in white wine compared to wine settled without fining agents. Addition of yeast hulls at 5.0 g/L to a Shiraz wine containing ca. 5 μg OA/kg yielded a 43% reduction. Gelatin was also slightly effective. Storage of wine for 10–14 months resulted in a decrease in OA concentration of 22% and 29% for white and red wines, respectively.     

Removal of pesticides from red and white wine by the use of fining and filter agents

Effects of the use of the fining and filtration agents, diatomaceous earth, bentonite, polyvinylpoly-pyrrolidone and activated carbon, on the removal of seven fungicides (carbendazim, chlorothalonil, fenarimol, metalaxyl, oxadixyl, procymidone and triadimenol) and three insecticides (carbaryl, chlorpyrifos and dicofol) from wines were investigated. Carbendazim was determined by high performance liquid chromatography (HPLC) after quantitative conversion into 2-aminobenzimidazole (2AB). The concentrations of all the other compounds in wine were quantified using a multi residue assay involving solid phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). After treatment and processing, conducted under conditions simulating those that are typical in Australian commercial winemaking, the greatest reduction in concentration in all treatments was for chlorothalonil, chlorpyrifos and dicofol. There was a significant relationship between the extent of removal of each pesticide and its solubility in wine, such that the lower the solubility, the greater the extent of removal. Activated carbon had the largest effect on the removal of most pesticides, while bentonite had a major effect on the removal of carbendazim. For all compounds and agents, the rate of removal was greater in white wine than in red wine.     

Lead in wine: a case study on two varieties at two wineries in South Australia

Sources of lead in wine were inferred from systematic assay of grapes must and wine, during winemaking. Two Australian wineries were monitored during the 1994 vintage with respect to vinification of Riesling and Shiraz. Juice and wine samples were collected at several process stages from crushing through to bottling, and were analysed for their total lead concentration by graphite furnace atomic absorption spectrometry. Selected samples were subsequently analysed for lead isotope ratio (fingerprinting method) to infer possible sources of lead in samples. Lead concentration in fermenting must was found to vary during vinification. In particular, lead concentration increased significantly in open-top vessels, in holding bins and during pressing. Juice and wine stored in concrete or waxed wood also had a significantly higher concentration of lead compared to juice or wine stored in stainless steel. Moreover, fining with bentonite or filtering with diatomaceous earth contributed further to final lead concentration, while fermentation, both primary and secondary, removed lead Overall, wines processed via these different systems still contained only traces of lead, and generally less than 30 μg/L (30 micrograms per litre). These trace levels are of no concern to human health when such wines are consumed in moderation.     

Heat-unstable protein removal by different bentonite labels in white wines

The relationship between heat-unstable wine proteins and bentonite fining is still a matter of debate. Some authors have suggested that bentonite removes protein according to matrix parameters, but others have described it as selective for some protein classes. The aim of our work was to characterize the fining effects of five different types of activated sodium bentonite on two international white wines (Chardonnay and Sauvignon blanc). The physical properties of the bentonite samples and the general wine characteristics were determined, and protein removal was evaluated with gradient SDS-PAGEs, protein quantification and subsequent band identification by MALDI-TOF mass spectrometry. For the Chardonnay and Sauvignon blanc tested in the study, fining with specific bentonite labels to remove select residual proteins, some of which are potential allergens, was very promising. The removal of a single protein by bentonite affected the wine’s thermal stability.     

Quality of base and sparkling wines as influenced by the type of fining agent added pre-fermentation

A comparison of the effect on base wines of pre-fermentative clarification between a fining mixture (potassium caseinate, bentonite and cellulose microcrystalline) and bentonite was carried out. Fining agents were added to two grape juices from different cultivars: Macabeo and Parellada. These varietal wines are used for making sparkling wine within the appellation (certified brand of origin) Cava. Vinification was done in parallel on an industrial scale (100 000 l). The use of the fining mixture in grape juice made the fermentations more complete and gave wines with less browning ability, more foam stability time and a lower content of nitrogenous fraction, polyphenols and some volatile compounds than the wines treated with single bentonite. Sensorial analysis showed that the wines produced with the use of different fining agents had different organoleptic characteristics. In addition, the effect of fining agent added pre-fermentatively was observed on some components of sparkling wines.     

Foam aptitude of Bobal variety in white sparkling wine elaboration and study of volatile compounds

Fining agents can also have an effect on the flavor components of the must, and other compounds which are important for the sensory characteristics and in the case of sparkling wine, the foam quality. The influence of fining agents and tirage solution, on volatile compounds, and foam characteristics of sparkling wines made from grapes of the Bobal variety was studied. The data obtained show how the fining agent affects the foam properties and the final volatile composition of sparkling wines. In this study, it was bentonite with gelatine that produced amounts of acetates and esters. The use of Colle 2P in the tirage solution means that more aromatic sparkling wines with better foam characteristics can be obtained.     

The evaluation of remedial treatments for wine affected by Harmonia axyridis

This study evaluated the efficacy of a range of commercially available fining agents and other interventions on reducing 2‐isopropyl‐3‐methoxypyrazine (IPMP) concentration and taint characteristics of white and red wine affected by Harmonia axyridis (HA). Wines fermented in the presence of HA beetles were treated with bentonite, activated charcoal, oak chips, deodorized oak chips and either ultraviolet (red wine) or visible (white wine) light. IPMP concentrations were lowered by activated charcoal in white wine and deodorized oak in red wine. Treatment with oak chips reduced the intensity of HA‐associated sensory attributes (‘ladybug taint’) in both white and red wines, while other applications generally had no effect on white wine and limited effect on red wines.     

Evaluating potential alternatives to potassium caseinate for white wine fining: Effects on physicochemical and sensory characteristics

The use of potassium caseinate for wine fining can cause allergic reactions and must be included on wine bottle labels. The focus of this research was to determine if non-allergenic pea protein or polyvinylpolypyrrolidone (PVPP) are possible alternatives for wine fining. Trials were performed to compare the effects of these potential fining agents on phenolic compounds, browning potential, turbidity and sensory attributes. The results indicate that flavonoid and non-flavonoid phenols decreased (p < 0.05) in the wines treated with potassium caseinate, pea protein, and PVPP. All fining agents decreased (p < 0.05) wine colour. Potassium caseinate was the most effective fining agent for reducing browning potential. Pea protein and potassium caseinate resulted in increased clarity of the final wines. No sensorial differences (p < 0.05) were detected among the wines prepared with the different fining agents. This study provides information that could be used to select an appropriate alternative to potassium caseinate.     

Repercussion of the clarification treatment agents before the alcoholic fermentation on volatile composition of white wines

Albariño must was clarified with two fining agents, as bentonite and silica gel. Alcoholic fermentation was carried out at semi-industrial scale, and the concentration of free monoterpenes, norisoprenoids, C₆-alcohols, higher alcohols, fatty acids, ethyl esters, and acetates was then investigated. The use of bentonite allows loss of several volatile compounds compared to wine control. In a second step, the effect of clarification–stabilization treatments with silica gel on aromatic substances was compared in order to study this influence in white wines elaborated from different aromatic varieties (Albariño and Loureira). The results showed that the use of these fining agent plays a significant role in the wine volatile composition.     

不同下胶剂对浓缩型雪梨发酵酒的综合影响分析

以浓缩型雪梨发酵酒为试材,研究聚乙烯吡咯烷酮（PVPP）、皂土、大豆蛋白、商用复合澄清剂（FPR）、活性炭5种不同下胶剂对雪梨酒的浊度、色度、色调、色差、酒脚干质量、总多酚含量和感官品评的影响。结果表明,当下胶量为PVPP 0.8 g/L、皂土1.0 g/L、大豆蛋白0.3 g/L、FPR 0.8 g/L,活性炭1.4 g/L时,酒样在80 ℃、30 min加热测试中达到稳定;各处理样对酒的指标均存在显著性差异（P＜0.05）,其中活性炭对酒样色泽影响较大,酒脚增加最多,总多酚减少最小。大豆蛋白对酒样色泽影响较小,酒脚产生较少,对多酚影响较大,大豆蛋白及FPR处理组就外观、香气、风味等方面综合评分最为接近原酒。综上分析,0.3 g/L大豆蛋白处理样澄清透亮,香气丰富,更适于浓缩型雪梨发酵酒的下胶澄清。