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Updated Wine Color Reagents & Procedures

Spectrophotometric Methods

Inquire for EnoLyzerTM  & ChemWell-for-WineTM updated APPLICATIONS

(The ChemWell tests are described below)

 

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Anthocyanins & Wine PHENOLICS - OVERVIEW:  Phenolics are responsible for wine color, bitterness, and astringency.  Phenolic wine profiles are affected by fermentation and winemaking variables (skin contact, etc), grape variety, ripeness and vineyard variables. Measurement of Total Phenols, Anthocyanin, Color Density & Hue can provide valuable information for optimizing these processes.

 

Unitech's New Phenolics kits for your Spectrophotometer  Contact Unitech to automate these tests on your ChemWell for WineTM autoanalyzer.

1.      Antho UniFlex reagent measures the polyphenolic (i.e. ionizable) anthocyanin and red pigments; Absorbance is converted to Anthocyanin mg/L using a factor imperically derived by correlation to HPLC.

2.       P-PHEN enz –  Unitech Scientific’s new enzymatic Kit is specific for polyphenols in wine, with minimal reactivity to monomeric anthocyanins.  It is based on the enzyme Polyphenol Oxidase and reports Polyphenols mg/L in “Gallic Acid Equivalents”.

3.      PHEN-fc   – Unitech’s traditional (Folin-Ciocalteu) Reagent Kit is the best option for measuring total Phenolics (small & large Anthocyannins, tannins, etc.: Total Phenols mg/L in Gallic Acid equivalents. Refer to kit Directions to correct for interferrences (e.g. structures with phenol groups, such as sugars.)he mg/L Anthocyanin & Polyphenols results from these analyses provide an anchor for ABS assessments for Anthocyanin and wine color.

4.       Phen&Color Reagent Kit standardizes measurement of Wine Color, SO2 Bleaching & Ionization–Absorbance values are corrected for dilution1,2:

o        Wine Color (420, 520, 620nm)    

Yellow/brown wine pigments (tannins and oxidative end products of phenolic breakdown) are measured by ABS420nmRed pigments (free anthocyanins, red oligomeric and polymeric compounds) are measured by ABS520nm

In addition to ChemWell for Wine test procedures for Wine Color, the ChemWell automates Color Intensity, Density and  Hue(%);  From the Sample Screen, run either (or both) of the following Index:

o       Color Density: Yellow + Red  (420 + 520nm)

o       Color Hue: % Yellow/Red   % (420nm/520nm)

  • SO2 Bleaching3 effect on red Wine Color (520nm) - Anthocyanin monomers & polymers

SO2 Reagent is used to measure Polymeric Anthocyanins following sulfite bleaching of smaller Antho pigments (remaining pigments are measured at 520nm)

ACE Reagent is used to measure Total Anthocyanins; acetaldehyde remove any sulfite bleaching influence and total Anthocyanin is measured at 520nm

These measurements permit calculation of co-pigmented and monomeric anthocyanins (from the ChemWell Sample Screen, run either (or both) Index:

o       Co-Pigmented Antho  = Total Antho – Color 520

o       Monomeric Antho = Color 520 - Polymeric Antho

  • Antho Ionizing Reagent shifts wine pigments toward the Red spectrum (520nm ABS) and measures total ionizable anthocyanins

5.   Flavonol 340nm (Reagent in development) ionizes wine pigments, incubates, corrects for dilution; the (340nm ABS) results are proportional to Flavonol (Catechin) content.

 

NOTES: 

1     These tests are similar to Unitech’s original ChemWell Wine Color test protocols, except Wine Dilutions are made directly into the Wells (faster, more accurate and  convenient that using dilution tubes in the Reagent Rack.)

2     Unitech observes more consistent phenolic evaluations using our Color Diluent (as opposed to using DI Water in these “Color” assays (420, 520, 620nm.)  This Color Diluent measures Wine Color at pH 3.3 (wine ABS values change as pH in the wine varies.)  ChemWell ABS values are automatically corrected for turbidity & dilution, then adjusted to 1cm light

3     The 520nm ABS of single and dimeric phenols (e.g. Anthocyanin pigments) decreases in the presence of SO2, due to the formation of anthocyanin-sulfite complexes 

 

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·       Choice Of Kit Sizes (30, 75, 250-Tests)

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P: 562.924.5150     F: 562.809.3140     email info@unitechscientific.com           www.unitechscientific.com