Wineries looking for optimizing analysis solutions to determine Phenolic Potential.

Many wineries use the 'Glories Index' as the primary analysis to quantify the phenolic potential of their grapes.

This is the case with ‘Cape Mentelle Winery’ in Australia, which monitors the phenolic potential of all their Cabernet and other red varieties during the ripening process to determine the optimal harvest time and achieve the best quality in their future wines.

The Glories Index is a widely used metric in viticulture and enology to assess grape ripeness and phenolic maturity, particularly for red grape varieties. It measures the levels of anthocyanins (responsible for color) and tannins (key to structure and aging potential) in grape skins. The index helps winemakers decide the optimal time for harvest.

Results provided by the method

• Sample pretreated at pH 1: Total potential in anthocyanins.
• Sample pretreat at pH 3.2: Total potential in extractable anthocyanins in the pH of the wine.
• EA%: Anthocyanins extractability.
• RPT: Total polyphenolic richness of the grapes.
• MP%: Seed maturity, representative of the contribution of seed tannins.

A higher ratio (>0.8) suggests advanced phenolic maturity, with good extractability of pigments
and tannins.

A lower ratio (<0.5) suggests the grapes may still be underripe, leading to less efficient extraction during winemaking.

Practical applications in winemaking

1. Harvest Decision-Making:

The Glories Index helps winemakers determine the best harvest time for achieving the desired tannin and color balance in wines.

It complements traditional ripeness measures like sugar content (°Brix), titratable acidity (TA), and pH.

2. Tailored Winemaking:

Grapes with high extractable anthocyanins may require gentler maceration techniques to avoid excessive tannins.

Lower extractability might prompt adjustments, such as extended maceration or specific fermentation techniques, to optimize phenolic extraction.

3. Predicting Wine Style:

High anthocyanin and tannin levels are ideal for structured, age-worthy wines.

Lower levels suit lighter, fresher wine styles.

4. Vineyard Management Feedback:

If the index indicates phenolic immaturity, viticultural adjustments (e.g., thinning, canopy management) can be implemented in future seasons.

The Glories method need two different sample pretreatment as mentioned in the bibliography.(1, 2)

A unique sample will be divided in two to quantify all the phenolic compounds.The sample will be adjusted to pH 1 and pH 3.2 separately.

After 4 hours of maceration and pretreatment:

• Sample 1 (pH 1) will be run in BioSystems Analyser with Anthocyanins kit to get your Total Potential Anthocyanins.

• Sample 1 (pH 3.2) will be run in BioSystems Analyser with Anthocyanins kit to get your Extractable Anthocyanins.

The results of the BioSystems method, that includes the slope correction are comparable to those obtained by the Glories method with the original extra steps and dilutions after the pretreatment.

For introducing this new technique in your Y15 or SPICA analyser, please contact your Application Support.

For quantify RPT % through IPT analysis at 280nm you can work with a Spectrophotometer or ask to BioSystems about SPICA analyser.