bANT:pTAN
The Bound Anthocyanins to Protein-Precipitable Tannins ratio (bANT:pTAN) is a useful metric for understanding astringency in red wines. Free Anthocyanins increase the polarity of the Tannins they polymerize with, thus decreasing their astringency. Bound Anthocyanins are also more prone to folding, making them good precursors to colloids which incorporate structural and flavor compounds together in the finished wine.
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<0.1: The wine is likely very astringent, linear, and drying. These wines typically come from grapes with high tannin and low pigment. They take time to age unless deliberately oxidized to soften astringency.
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11-0.15: The wine likely has moderate to high astringency. This is a classic ratio that a lot of wines fall under, and a common ratio naturally achieved throughout primary and secondary fermentation.
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16-0.2: The wine likely has low to moderate astringency, bringing forward the flavor and structure integration. Highly concentrated wines with this ratio are sought after today for their simultaneous drinkability and age-ability. Think Cabernet Sauvignon from Napa.
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2-0.25: The wine likely has low astringency, imparting a plush and round mouthfeel. This high ratio has become associated with high-scoring wines.
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>0.25: The wine likely has very low perceived astringency. This ratio is commonly achieved by restraining tannin relative to anthocyanin extraction. We generally want to maximize bound anthocyanins, but over-restraining tannins can depreciate mouthfeel by limiting structure.
Free anthocyanins aren’t the only compounds in wine that modulate tannin astringency, but they are naturally occurring and highly effective. Think of these ratios like archetypes. They are useful for creating generalizations about astringency and wine style but do not encapsulate a wine's complexity or true nature. We have found these ratios to be generally true, but certainly not without exception. For instance, wines with low structure (pTAN) and a ratio of 0.1 tend not to be astringent, and wines with high structure (pTAN) and a ratio of 0.2 tend to be astringent. This is because oxygen also plays a critical role in modulating astringency by increasing tannin polarity and therefore decreasing astringency. The higher the structure, the more Bound Anthocyanin and oxidation are required to incorporate astringency into the mouthfeel. This is why wines from Barolo often need decades to age before consumption, and wines from Napa Valley can be consumed sooner despite often having similar ranges of tannins. Nebbiolo is a low-color varietal and Cabernet Sauvignon is a high-color varietal.
To learn more about the bANT:pTAN ratio and how it applies to winemaking, become a Bound member.
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FAQs
Frequently Asked Questions
Supplies
- We supply 50 mL centrifuge tubes and labels upon request.
Sample
- Sample your wine in a way that is most representative of the entire lot (i.e. practice flushing your sample valve, collecting after movements like pumpovers, stirring your barrel, etc.).
Label
- Label each sample appropriately with your Client ID, Sample Date, and Sample ID. Samples for Phenolics analysis also require a Crush Date, Varietal, and Appellation. The analysis cannot be performed without the applicable information for each sample.
- Mark the sample type. ”Juice” applies to grapes and juice samples before fermentation. ”Must” applies to samples undergoing primary fermentation. ”Wine” applies to samples after fermentation.
- Select “Standard” for our corresponding juice, must, and wine panels, or select “Phenolics” for our phenolics panel. SO2 analysis can be included with the standard panel by selecting “with SO2”. Individual parameters can be added at the bottom of the label. A full list can be found on our ANALYSES page.
Clients are able to submit samples by scheduling a pickup, delivering directly to our lab, or via the mail.
To arrange for pickup, clients must be located near Lompoc, Buellton, Santa Ynez, Goleta, or Santa Barbara and notify us by 11 am for same-day retrieval. Established clients can also use our quick scheduling function by clicking the “LAB CLIENTS” tab on the bottom right hand corner of the screen. Be sure to select the correct date and provide all necessary details including instructions for pickup or requests for sampling supplies. Please contact us for more information.
- We provide same-day results by 7 pm with a guaranteed turnaround within 24 hours of sample receipt.
- Samples that are not analyzed same-daly are refrigerated overnight and analyzed first thing the next morning.
- Results are delivered via email in PDF format and uploaded to your account.
- Our invoices are sent via email and are due upon receipt.
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- You can also opt-in to our invoice autopay feature by clicking “SIGN UP FOR AUTOPAY” on your account page.
To ensure their stability, we ask our clients either freeze or boil their juice / fermenting wine samples before shipment. Please note that boiling or freezing your samples may influence your results and we cannot guarantee their validity. Please contact Bound with any additional questions about sample preparation before shipment. We recommend expedited same-day to one-day shipping with a tracking number included.
Frozen
Samples can be placed in a freezer 24-hours in advance and shipped with an ice pack. Do not over-fill the polypropylene tubes or use glass containers as the frozen liquid will expand and could pose a safety concern. Freezing samples is a better alternative to boiling when analyzing compounds like ethanol, volatile acidity, free sulfur, and phenolics. Label each sample as "FROZEN".
Boiled
We generally do not recommend boiling your samples as it can significantly alter the chemistry of your sample. If necessary, samples can be boiled in their 50 mL polypropylene centrifuge tubes with a loosely fitted cap on top. Polypropylene tubes can be boiled up to 10 minutes, but be sure not to over boil as exposure to high temperatures can change your results. Label each sample as "BOILED".
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