Macrowine 2021
IVES 9 IVES Conference Series 9 Some applications come from a method to concentrate proteins

Some applications come from a method to concentrate proteins

Abstract

All techniques usually used to assay proteins was not reliable in vegetable extract due to interferences with the components included in extracts like polyphenols, tanins, pectines, aromatics compounds. Absorbance at 280nm, Kjeldhal assay, Biuret and Lowry methods, Acid Bicinchonique technique and Bradford assay give the results depending on the composition of extract, on the presence or not of detergent and on the raw material (Marchal, 1995). Another difficulty in these extracts for the quantification of proteins comes from the large amount of water included in vegetable and the low concentration of proteins. Thus in red wines, proteins are usually not taken into account due to their low concentration (typically below 10 mgL-1) and to the presence of anthocyanis and polyphenols. Due to all these defects, alternative test should be developed. The perfect protein assay would exhibit the following characteristics: fast, easy to use, sensitive, accurate, precice and free from interferences. Futhermore this assay should be compatible with all substances commonly found in protein samples and at low concentration. Our purpose in this work is to combine the concentration of proteins by bentonite with separation electrophoretic 1D SDS Page and to examine some applications. First, wines were fined with 100g/hl of bentonite is largely sufficient to adsorbe all proteins (Paetzold and al.,1990). In these conditions, we observed at low concentrations of bentonite (under 20g/hl), the bentonite Electra® adsorbed only β glucanases and chitinases. Second after desorption by Laemmli buffer, proteins were separated by SDS-PAGE and quantified after coloration with Coomassie Blue R-250 by scanning coupled to the image analysis TotalLab software (Sauvage and al., 2010). The gels after destaining were scanned with a transmission scanner at 300 dpi to obtain a digitised image. The software compared the volume (area x intensity of each pixel) of each band to the volume of BSA band (included in standard file). Each band was characterized by the molecular weight and the quantity of proteins expressed in µg equivalent BSA. The sum of each band gave the total pool of proteins included in each sample. The standard deviation measured on 6 same sample on Chardonnay wine was 11%. The response was linear for each band up to 1µg/band. By this method we also got the relative composition of the majority of proteins. Last, but not least, proteins were desorbed from bentonite with buffer to denature proteins or only with a buffer to conserve the native form of proteins (like Tris buffer or NaCl solution). After this experimentation we checked if [1] Marchal R. Ph. Thesis, university of Reims, 1995.

[1] Paetzold M., Dulau L., Dubourdieu D. J.Inter.Sci.Vigne Vin, 1990, 24, 13-28. [2] Pocock K.F., Waters E.J. Aust.J.Grape Wine Res., 4, 136-139. [4] Sauvage F.X., Bach B., Moutounet M., Vernhet A. 2009, 118, 26-34.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Poster

Authors

Francois-Xavier Sauvage*, Patrick Chemardin

*INRA

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

Related articles…

Correlations between sensory characteristics and colloidal content in dry white wines

Must clarification is an important step occurring just after grape extraction in the elaboration of white wine, consisting in a solid-liquid separation. Traditionally, low must turbidity, around 50-150 NTU, is generally reached in white winemaking in order to prevent reductive aromas and facilitating alcoholic fermentation. Alternatively, a higher turbidity (300 NTU or above) can be sought for reasons such as a better expression of grapes identity (terroir), or for getting a must matrix that could supposedly lead to wines having greater ageing potential.

Simultaneous monitoring of dissolved CO2 and collar from Rosé sparkling wine glasses: the impact of yeast macromolecules

Champagne or sparkling wines elaborated through the same traditional method, which consists in two major yeast-fermented steps, typically hold about 10 to 12 g/L of dissolved CO2 after the second fermentation in a closed bottle. Hundreds of molecules and macromolecules originating from grape and yeast cohabit with dissolved CO2; they are essential compounds contributing to many organoleptic characteristics (effervescence, foam, aroma, taste, colour…). Indeed, the second alcoholic fermentation and the maturation on lees (which may last from 12 months up to several years) both induce various quantitative and qualitative changes in the wine through the action of yeast, as listed hereafter: development of aromas during aging on lees, release of nitrogen compounds during autolysis and release of macromolecules (polysaccharides, lipids, nucleic acids) in wine.

Using elicitors in different grape varieties. Effect over their phenolic composition

Phenolic compounds are very important in crop plants and have been the subject of a large number of studies. Three main reasons can be cited for optimizing the level of phenolic compounds in crop plants: their physiological role in plants, their technological significance for food processing, and their nutritional characteristics1 Indeed, an enormous diversity of phenolic antioxidants is found in fruits and vegetables, and their presence and roles can be affected or modified by several pre- and postharvest cultural practices and/or food processing technologies (Ruiz-García et al. 2012, Goldman et al. 1999, Tudela et al. 2002). In winegrapes, the technological importance of phenolic compounds, mainly flavonoids, is well-known.

Quantification of red wine phenolics using ultraviolet-visible, near and mid-infrared spectroscopy combined with chemometrics

The use of multivariate statistics to correlate chemical data to spectral information seems as a valid alternative for the quantification of red wine phenolics. The advantages of these techniques include simplicity and cost effectiveness together with the limited time of analysis required. Although many
publications on this subject are nowadays available in the literature most of them only reported feasibility
studies. In this study 400 samples from thirteen fermentations including five different cultivars plus 150
wine samples from a varying number of vintages were submitted to spectrophotometric and chromatographic phenolic analysis.

On the losses of dissolved CO2 from laser-etched champagne glasses under standard tasting conditions

Under standard champagne tasting conditions, the complex interplay between the level of dissolved CO2 found in champagne, its temperature, the glass shape, and the bubbling rate, definitely impacts champagne tasting by modifying the neuro-physico-chemical mechanisms responsible for aroma release and flavor perception. Based on theoretical principles combining heterogeneous bubble nucleation, ascending bubble dynamics and mass transfer equations, a global model is proposed (depending on various parameters of both the wine and the glass itself), which quantitatively provides the progressive losses of dissolved CO2 from laser-etched champagne glasses.