Influence of fatty acids on wine foaming

The influence of fatty acids (free and bound as ethyl esters) on wine foaming was studied in different white wines and the corresponding sparkling wines. Moreover, from three of these wines the foam formed by CO(2) injection was separated, and two fractions were then obtained: foam wine (FW) and remainder wine (RW). In these fractions and the sparkling wines produced from them, foam properties and fatty acids were also determined. The free fatty acids C8, C10, and C12 were negatively correlated with foamability (HM), whereas the ethyl esters of hexanoic, octanoic, and decanoic acids were positively related to HM. The value of HM was directly proportional to the ratio of esterified to unesterified fatty acids. This was confirmed by the changes that occur in the esterification ratio during the second fermentation and aging. No influence was observed on either the Bikerman coefficient or the stability time of foam.     

Determination of the grape invertase content (using PTA-ELISA) following various fining treatments versus changes in the total protein content of wine. relationships with wine foamability

Proteins have proven to play a major role in the stabilization of foam in Champagne wines despite their low concentration that ranges from 4 to 20 mg/L. The aim of this study was to evaluate the effect of fining on total protein and grape invertase contents of champenois base wines and their foaming properties. Data showed that fining and especially the use of bentonite at doses ranging from 10 to 50 g/hL leads to a significant decrease in the total protein content of wines together with that of the grape invertase content, with such a decrease being very detrimental to the foaming properties of the treated wines in terms of foam height (HM) and foam stability (HS). Only a slight decrease in the total protein content, in the grape invertase concentration, and in the foam quality of wines was observed when using casein (10 and 20 g/hL) or bentonite combined with casein (both at 20 g/hL). Our study thus clearly establishes the good correlation existing between the wine protein concentration and its foaming properties. A remarkable correlation was observed between the decrease in the grape invertase content and the total protein content of wines, following bentonite treatments, suggesting that the grape invertase (which represents at least 10-20% of the wine proteins) follows a similar behavior upon fining to other proteins of Champagne wines, despite the high molecular mass and the highly glycosylated structure of this particular protein. Moreover, the decrease in total protein and grape invertase contents of wine after fining with bentonite was found to be correlated with a decrease in the foaming properties of the corresponding wines (with respectively R(2) = 0.89 and 0.95).     

Prediction of wine foaming.

A procedure for estimating the foam properties of sparkling base wines without specifically measuring foam was developed. This method was based on mathematical equations established between the usual parameters of wine quality control (independent variables of the equations) and the wine foam parameters [foamability (HM), Bikerman coefficient (Sigma), and surface tension (ST)] obtained with the specific equipment (dependent variables of the equations). Ninety-six white wines from the Cava region produced at industrial scale were used to establish these equations. Two predictive equations that could be applied to different types of wine from different origins were obtained: one to predict the foamability (HM) and the other to predict the Bikerman coefficient (Sigma). Moreover, the database of foam parameters of the 96 wines allowed a qualitative assessment of wine foaming values.     

Synergistic effect of high and low molecular weight molecules in the foamability and foam stability of sparkling wines

The foam of sparkling wines is a key parameter of their quality. However, the compounds that are directly involved in foam formation and stabilization are not yet completely established. In this work, seven sparkling wines were produced in Bairrada appellation (Portugal) under different conditions and their foaming properties evaluated using a Mosalux-based device. Fractionation of the sparkling wines into four independent fractions, (1) high molecular weight material, with molecular weight higher than 12 kDa (HMW), (2) hydrophilic material with molecular weigh between 1 and 12 kDa (AqIMW), (3) hydrophobic material with molecular weigh between 1 and 12 kDa (MeIMW), and (4) hydrophobic material with a molecular weight lower than 1 kDa (MeLMW), allowed the observation that the wines presenting the lower foam stability were those that presented lower amounts of the MeLMW fraction. The fraction that presented the best foam stability was HMW. When HMW is combined with MeLMW fraction, the foam stability largely increased. This increase was even larger, approaching the foam stability of the sparkling wine, when HMW was combined with the less hydrophobic subfraction of MeLMW (fraction 3). Electrospray tandem mass spectrometry (ESI-MS/MS) of fraction 3 allowed the assignment of polyethylene glycol oligomers (n = 5-11) and diethylene glycol 8-hydroxytridecanoate glyceryl acetate. To observe if these molecules occur in sparkling wine foam, the MeLMW was recovered directly from the sparkling wine foam and was also analyzed by ESI-MS/MS. The presence of monoacylglycerols of palmitic and stearic acids, as well as four glycerylethylene glycol fatty acid derivatives, was observed. These surface active compounds are preferentially partitioned by the sparkling wine foam rather than the liquid phase, allowing the inference of their role as key components in the promotion and stabilization of sparkling wine foam.     

Foam aptitude of trepat and monastrell red varieties in cava elaboration. 2. Second fermentation and aging

The foam properties of sparkling wines (Cava) made from two red autochthonous grape varieties, Trepat and Monastrell, and coupages, including different percentages of them, were studied during second fermentation and aging. The effect of second fermentation on foam gave the highest decreases when the base wines had the highest foam values, while gave the lowest decreases or even increases for the base wines with the lowest foam characteristics. However, the greater the HM and Sigma of the base wine, the greater the foam values of the sparkling wine. Base wine determinations for quality control in cellars could provide information about future sparkling wine foaming. Acidity parameters, ethanol, sulfur, and polysaccharides contents were correlated to foam characteristics in the sparkling wines. In terms of color and foaming, wines made from the red varieties Trepat and Monastrell blended with white variety wines could be appropriate for elaborating "blanc de noirs" sparkling wines.     

Influence of lysozyme treatments on champagne base wine foaming properties

The objective of this study was to estimate the effect of lysozyme on the foaming characteristics of Champagne base wine. Lysozyme additions were made to the musts and also to the wines before and after bentonite or charcoal treatments, which remove endogenous proteins. Treatments with bentonite diminished foamability and foam stability of wines, whatever the dose (30 or 80 g/hL) and variety [Chardonnay, -28%; Pinot noir, -20% (at 30 g/hL)]. An addition of lysozyme in must raised Pinot noir wine foamability by 21%, whereas the difference is hardly perceptible for Chardonnay wine (+3%). Pinot noir and Chardonnay wines, originating from lysozyme-treated musts, in addition to bentonite treatment on the wine, presented higher foamability than wines treated only with bentonite. Lysozyme was removed (91-100%) by the bentonite treatment. Then, it was not responsible for the increase in foamability but seemed to have a protective effect on the wine proteins. When wines were initially treated with bentonite (150 g/hL) and then enriched with 80 g/hL lysozyme, this enzyme was not able to restore foaming properties. Treatments with charcoal always diminished foamability. The average increase in foamability due to an addition of lysozyme after charcoal treatment (80 g/hL) was 23%. Results showed a real positive effect of lysozyme on foam stability when wines have to be treated with charcoal (+25% and +56% for the Pinot noir wine and the Chardonnay wine, respectively, at 30 g/hL).     

Antioxidant action of glutathione and the ascorbic acid/glutathione pair in a model white wine

Glutathione was assessed individually, and in combination with ascorbic acid, for its ability to act as an antioxidant with respect to color development in an oxidizing model white wine system. Glutathione was utilized at concentrations normally found in wine (30 mg/L), as well as at concentrations 20-fold higher (860 mg/L), the latter to afford ascorbic acid (500 mg/L) to glutathione ratios of 1:1. The model wine systems were stored at 45 °C without sulfur dioxide and at saturated oxygen levels, thereby in conditions highly conducive to oxidation. Under these conditions the results demonstrated the higher concentration of glutathione could initially provide protection against oxidative coloration, but eventually induced color formation. In the period during which glutathione offered a protective effect, the production of xanthylium cation pigment precursors and o-quinone-derived phenolic compounds was limited. When glutathione induced coloration, polymeric pigments were formed, but these were different from those found in model wine solutions without glutathione. In the presence of ascorbic acid, high concentrations of glutathione were able to delay the decay in ascorbic acid and inhibit the reaction of ascorbic acid degradation products with the wine flavanol compound (+)-catechin. However, on depletion, the glutathione again induced the production of a range of different polymeric pigments. These results highlight new mechanisms through which glutathione can offer both protection and spoilage during the oxidative coloration of a model wine.     

Influence of Fatty acids on foaming properties of cider

Seventy-seven ciders from four consecutive harvests, which were produced at industrial scale by cider-makers from the region of Asturias (northern Spain), were analyzed to evaluate their foam capacity. The Bikerman method for the evaluation of foaming characteristics was adapted to ciders. In foaming, there are two parameters, foam formation and foam stability, which are found to be related to each other. To determine the relationship between fatty acid content and foaming properties of cider, the multivariate analysis technique of canonical correlation analysis was applied. Foam stability is positively related to the content of caprylic acid. Foam height is positively related to linolenic, pentadecanoic, and palmitic acid and negatively related to stearic and linoleic acid.     

亚热带2种针叶林土壤碳氮磷储量及化学计量比对混交的响应

针叶林混交阔叶树是改善土壤肥力、增强林地养分循环的重要措施,而混交效应受到针叶树种自身特性的影响,马尾松(Pinus massoniana)和湿地松(P.elliottii)是亚热带地区广泛种植的针叶树种,但目前2种针叶林对阔叶树混交的响应特征还不清楚。选取马尾松、湿地松纯林以及木荷(Schima superba)补植后形成的马尾松—木荷和湿地松—木荷混交林为研究对象,采集剖面土壤样品,测定土壤容重、有机碳(OC)、全氮(TN)和全磷(TP)含量,计算碳氮磷储量及化学计量特征,比较不同森林类型间的异同。混交阔叶树显著增加了马尾松林0—60cm各土层OC含量,而湿地松纯林与其混交林间OC含量无显著差异。同时,混交增加了2种针叶林土壤TN含量。马尾松林混交后0—60cm土层碳储量显著增加95.8%,而混交阔叶树对湿地松林土壤碳储量无显著影响。混交阔叶树后马尾松和湿地松林0—60cm土壤总氮储量分别增加了15.8%和28.4%,但混交对土壤磷储量无显著影响。混交显著增加了马尾松林0—40cm各土层C/N,而降低了湿地松林0—10cm土层C/N。混交阔叶树后马尾松林0—20cm土层C/P和0—10cm土层N/P显著增加,而混交仅增加湿地林0—10cm土层N/P。混交阔叶树增加了针叶林土壤氮储量,但对磷储量无显著影响,同时混交改变了土壤碳氮磷生态化学计量特征。与湿地松林相比,马尾松林土壤养分含量、储量及其化学计量特征对混交的响应更敏感。     

Evidence for protein degradation by Botrytis cinerea and relationships with alteration of synthetic wine foaming properties

Botrytis cinerea is an important fungal pathogen particularly dreaded in the cool climate vineyard. It is responsible for important damage, especially the decrease in foamability of sparkling wines, such as Champagne. Different studies have shown that proteins are largely involved in the stabilization of Champagne foam despite their low concentration. Other works demonstrated changes in the electrophoretic characteristics of must proteins originating from botrytized grapes, although the cause of such alterations was never explained. In the first part of this study, results showed the release by B. cinerea of 3.5 mg/L total proteins in a synthetic liquid medium. Among these proteins, the presence of a protease activity on bovine serum albumin (BSA) and must proteins was demonstrated by using a colorimetric method and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the model wine, the Bradford method showed a BSA loss of 66% after 24 h and a loss of 96% after 120 h. In the same model wine, the soluble must protein concentration decreased by 35% after 1 week and by 53% after 2 weeks while the control showed no protein loss. B. cinerea proteases were then able to degrade BSA and must proteins and were above all active at must and wine pH and in the presence of ethanol and SO(2). The second part of this work was dedicated to the relationship between the presence of B. cinerea proteases and its effects on the synthetic wine foaming properties. The addition of a B. cinerea culture medium (1/33 v/v) to the synthetic wine containing 21 mg/L soluble grape proteins induced a decrease in foamability by 60% after 1 week. For BSA in the model wine, the foamability decreased by 32% after 24 h and by 95% after 120 h, as shown by the colorimetric method. These experiments demonstrate for the first time the relationship between B. cinerea protease activity and the decrease in wine foaming properties.     

Isolation and characterization of a thermally extracted yeast cell wall fraction potentially useful for improving the foaming properties of sparkling wines

Two different yeast cell wall extracts were obtained using enzymatic digestion and thermal treatment. The effects of the extracts obtained on the foaming properties of a model wine and two sparkling wines were studied. The model wine and sparkling wines, supplemented with the thermal extract, presented better foaming properties than did the samples supplemented with the enzymatic extract. The fractioning (Con A chromatography) and characterization (SDS-PAGE, SEC, GC, and RP-HPLC) of both extracts showed that the fraction responsible for the foaming properties is constituted by mannoproteins with a relative molecular weight between 10 and 30 kDa, presenting an equilibrated composition of the hydrophobic and hydrophilic protein domains. This thermal extract did not modify the protein stability in both the model wine and the sparkling wines. These results demonstrate that the enrichment of a sparkling wine with mannoproteins extracted by mild heat procedures will contribute to improving its foaming properties.     

黑加仑果浆微波辅助泡沫干燥特性

为了研究微波辅助泡沫干燥方法对黑加仑果浆脱水的适用性,该文选择了合适黑加仑果浆起泡添加剂,并研究了起泡黑加仑果浆的微波干燥特性。选择食品级单甘酯和大豆分离蛋白作为起泡剂,发现其添加量对黑加仑果浆起泡特性有显著的影响,添加6.0%单甘酯和3.0%大豆分离蛋白作为起泡剂,以0.5%的羧甲基纤维素10 mL作为稳定剂,结果表明,加入这组添加剂的果浆在搅拌6 min时,得到的泡沫果浆具有较高膨胀性和稳定性。采用微波辅助泡沫干燥方法对起泡黑加仑果浆进行干燥,试验发现,随着初始微波强度的增大和料层厚度减小,物料的干燥强度显著增加。对比试验的结果表明,微波泡沫干燥速度及干品的色泽品质均优于热风泡沫干燥的。在连续带式微波干燥设备中,起泡黑加仑果浆推荐工艺参数为：初始微波强度14.0 W/g,料层厚度5 mm。因此,微波辅助泡沫干燥技术适用于黑加仑果浆脱水加工。     

Guar foaming albumin: a low molecular mass protein with high foaming activity and foam stability isolated from guar meal

The water extract of guar meal ( Cyamopsis tetragonolobus) was examined for its foamability. Compared with egg white, the extract showed an extraordinary foam stability: no drainage after 3 h of standing in contrast to 65% drainage for egg white at the same protein concentration. The acid-precipitated protein from the extract was responsible for the high foamability and designated guar foaming albumin (GFA). The foaming activity of GFA was 20 times higher than that of egg white. GFA consisted of two subunits with molecular masses of 6 and 11 kDa linked to each other through disulfide bonds. The cleavage of disulfide bonds in GFA affected the foamability only slightly. GFA remarkably decreased the surface tension of water at low protein concentrations. Immunoblotting analysis demonstrated that GFA did not react to the antisera from allergic patients against plant food. These results suggest that GFA serves as an effective food additive in developing protein-stabilized foam.     

Influence of wine structurally different polysaccharides on the volatility of aroma substances in a model system

The influence of native polysaccharides on wine organoleptic quality has not been yet clarified. Hence, the effect of purified fractions of arabinogalactan-proteins (AGPs), monomeric and dimeric rhamnogalacturonans II (mRG-II and dRG-II), and mannoproteins (MPs) on the volatility of various aroma substances was examined using the exponential dilution technique. The volatility of isoamyl acetate and ethyl hexanoate in a model wine system was not affected upon addition of wine polysaccharides in the range 5-20 g/L. At higher levels, the two esters were significantly retained in solution in the presence of the protein-rich polysaccharides MP0 and AGP0 and weakly salted out in the presence of the uronic acid-rich fractions AGP4, mRG-II, and dRG-II. In addition, the volatility increase caused by dRG-II on the esters was reversed when water was used as the solvent. 1-Hexanol exhibited retention in water with four fractions in the strength order AGP0 > dRG-II > mRG-II > AGP4 but was strongly salted out in the presence of fraction MP0. Furthermore, the diacetyl activity in water was overall not modified increasing only at high concentrations of AGP4. Reference polysaccharides dextrin and dextran were used for binding strength comparison.     

Sulfate--a candidate for the missing essential factor that is required for the formation of protein haze in white wine

Protein haze formation in white wine is dependent on the presence of both wine protein and other unknown wine components, termed factor(s) X. The ability to reconstitute protein haze upon heating artificial model wine solutions (500 mg/L thaumatin, 12% ethanol, 4 g/L tartaric acid) to which candidate components were added was employed to identify factor(s) X. No protein haze was formed in the absence of additives. The individual or combined addition of caffeic acid, caftaric acid, epicatechin, epigallocatechin-O-gallate, gallic acid, or ferulic acid at typical white wine concentrations did not generate protein haze. However, PVPP fining of commercial wines resulted in a reduction in protein haze, suggesting that phenolic compounds may play a modulating role in haze formation. To elucidate the nature of the unknown factor(s) wine was fractionated and fractions were back-added to model wine and tested for their essentiality. Wine fractions were generated by ultrafiltration, reverse-phase chromatography, and mixed-mode anion-exchange and reverse-phase chromatography. The only purified fraction containing the essential component(s) was free of phenolic compounds, and analysis by mass spectrometry identified sulfate anion as the dominant component. Reconstitution with KHSO4 using either commercially available thaumatin or wine proteins confirmed the role of sulfate in wine protein haze formation. The two main wine proteins, thaumatin-like protein and chitinase, differed in their haze response in model wines containing sulfate. Other common wine anions, acetate, chloride, citrate, phosphate, and tartrate, and wine cations, Fe(2+/3+) and Cu(+/2+), when added at typical white wine concentrations were not found to be essential for protein haze formation.     

Effect of sucrose on functional properties of soy globulins: adsorption and foam characteristics

In this contribution, we have analyzed the effect of sucrose on dynamic interfacial (dynamic surface pressure and surface dilatational properties) and foaming (foam capacity and foam stability) characteristics of soy globulins (7S and 11S). The protein (at 1 x 10(-3), 1 x 10(-2), 0.1, and 1 wt %) and sucrose (at 0, 0.25, 0.5, and 1.0 M) concentrations in aqueous solution and the pH (at 5 and 7), and ionic strength (at 0.05 and 0.5 M) were analyzed as variables. The temperature was maintained constant at 20 degrees C. We have observed the following. (i) The dynamics of adsorption (presence of a lag period, diffusion, and penetration at the air-water interface) of soy globulins depend on the peculiar molecular features of proteins (7S or 11S soy globulin) and the level of association/dissociation of these proteins by varying the pH and ionic strength, as well as the effect of sucrose in the aqueous phase on the unfolding of the protein. The rate of adsorption increases with the protein concentration in solution, at pH 7 compared to pH 5, at high ionic strength, and in the absence of sucrose. (ii) The surface dilatational properties reflect the fact that soy globulin adsorbed films exhibit viscoelastic behavior. The surface dilatational modulus increases at pH 7 compared to pH 5, but decreases with the addition of sucrose into the aqueous phase. (iii) The rate of adsorption and surface dilatational properties (surface dilatational modulus and phase angle) during adsorption at the air-water interface play an important role in the formation of foams generated from aqueous solutions of soy globulins. (iv) The increased interfacial adsorption (at high surface pressures) and the combined effects of interfacial adsorption and interfacial interactions between adsorbed soy globulin molecules (at high surface dilatational modulus) can explain the higher stability of the foam, with few exceptions.     

Sensory and foaming properties of sparkling cider

The effect of yeast strain and aging time on the chemical composition, analytical, and sensory foam properties of sparkling ciders has been studied. The analytical foam parameters (foamability, HM; Bikerman coefficient, sigma; and foam stability time, T(s)) were significantly influenced by aging and yeast strain. The sensory attributes (initial foam, foam area persistence, bubble size, foam collar, and overall foam quality) improved with aging time. Likewise, the yeast strain positively influenced the assessment of initial foam, foam area persistence, number of bubble chains, and overall foam quality. Significant and positive correlations were found between alcoholic proof, dry extract, total and volatile acidities, total phenols and total proteins, and sigma, whereas HM was negatively correlated with specific gravity, alcoholic proof, dry extract, and total proteins.     

Foaming properties of wheat gliadin

We studied gliadin solubility, surface tension and foam behavior, and the presence of different gliadin types in gliadin aqueous solutions and foams as a function of pH. Gliadin has excellent foaming properties only at neutral and alkaline pH. Its solubility is minimal near neutral pH, while almost complete at acidic and alkaline pH. Surface tensions of gliadin solutions are minimal around neutral pH, higher at alkaline pH, and highest at acidic pH, which corresponds well with their respective foaming properties. Foams at acidic and alkaline pH values are enriched in γ-gliadin, while foams at pH 8.0 have a similar distribution of α- and γ-gliadins. Thus, γ-gliadin predominantly contributes to the foaming properties of gliadin. The poor foaming properties of gliadin at pH 2.0 improve in the presence of 0.25 and 1.0% NaCl. It follows that the presence of positively charged amino acid residues hinders the formation of stable foam at acidic pH.     

Investigations on the high molecular weight foaming fractions of espresso coffee

The target of the present work was the chemical, technological, and sensorial characterization of the brown polymers (foaming fractions) of freshly prepared espresso coffee. The total foaming fraction (TFF) was precipitated with ammonium sulfate from the defatted freshly prepared beverage and then subfractionated by adding 2-propanol/water to give an insoluble fraction (foaming fraction A, FFA) and a soluble fraction (foaming fraction B, FFB). The former is almost colorless, has a higher molecular weight and a lower nitrogen content, and contains mostly polysaccharides, whereas the latter has a lower molecular weight and a higher protein/melanoidin content, which results in a darker color. FFB showed greater foaming capability, but FFA contributed to the stability of the foam. FFB was further fractionated with solid-phase extraction and characterized by different analytical methods (size exclusion chromatography, UV, HPLC-DAD, 1H NMR). All of the melanoidin-rich fractions showed antioxidant properties with the 2,2-diphenyl-1-picrylhydrazyl hydrate method.     

Fourier transform infrared spectroscopy and chemometric analysis of white wine polysaccharide extracts

Monovarietal white wines from Maria Gomes and Bical Portuguese Bairrada varieties were prepared according to different maceration and pectic enzyme clarification procedures. The polysaccharide-rich extracts, obtained by wine concentration, dialysis, and lyophilization, were fractionated by graded ethanol precipitation. A wide range of fractions rich in polysaccharides were obtained. Using the spectral region between 1200 and 800 cm(-)(1) of the FTIR spectra of the wine polysaccharide dry extracts, using PCA and CCA chemometric methods, it was possible to discriminate the extracts on the basis of their polysaccharide composition. Moreover, it was possible to identify the wine-making processes involved and their influence on the wine polysaccharides. Furthermore, a calibration model using a PLS1 was proposed for the quantification of mannose in the samples obtained by precipitation with 60% ethanol aqueous solutions. This information will allow an expeditious assessment and monitoring of the polysaccharide composition and modifications that occur during the wine-making processing and evolution.