Threshold detection (ISO 13301:2018)

Goal

Determine a panelist's detection threshold for a specific stimulus, following the 3-AFC (3-Alternative Forced Choice) procedure defined by ISO 13301:2018 and ASTM E679-19.

This is the quantitative test that, with ≥3 measurements in the last 6 months, qualifies a panelist at the selected level in the ISO 8586:2023 classification. The expert level is not reached through thresholds alone: it also requires a passed basic taste test within the last 6 months (see Panel training).

What 3-AFC is

At each concentration level:

• 3 samples are presented to the panelist.
• 2 are the plain presentation medium (water or the chosen base), without the stimulus.
• 1 contains the stimulus at the level's concentration.
• The panelist identifies which one contains the stimulus. The test finds the concentration at which they can consistently tell it apart from the control.

The BET is computed with the levels sorted by concentration (whatever order they were answered in): it's the geometric mean between the last missed level and the next one, the first of the final run of hits (ASTM E679-19). If the panelist gets every level right, the BET is the lowest level divided by √2; if they miss the highest one, it's the highest level multiplied by √2.

Concentration levels

AreaCacao prepares a series with increasing concentrations. You can configure between 4 and 8 levels (the minimum is 4; more than 8 causes sensory fatigue and is not allowed).

Available compounds

The stimulus can be any of these compounds, each with its reference substance:

The name you'll see in the compound picker is the one in the first column:

Presentation medium

You choose the base the stimulus is presented in, depending on how close you want to stay to the real product:

• Mineral water — the cleanest base, ideal for measuring pure sensitivity.
• Chocolate base (real matrix) — the stimulus in a chocolate matrix, for thresholds that are realistic for your product.
• Neutral base (cocoa butter + sugar) — a middle ground without cocoa's own notes.

Before you start

• Prepare the stimulus solutions per ISO 13301, at each level's concentration and in the chosen medium.
• Small cups, mineral water as a palate cleanser, an odor-free environment.

Steps

How to read the result

The leader sets a maximum BET to pass. The lower the BET, the more sensitive the panelist (they detect the stimulus at lower concentrations):

• BET at or below the maximum → the test is marked Passed for that compound.
• BET above the maximum → the test is marked Not passed. It may be due to personal sensitivity, noise in the tasting, or the test itself. Repeat it later. Even so, every threshold test measured in the last 6 months counts toward the ISO 8586 level, passed or not: the panelist becomes selected (or expert) once they accumulate ≥3; a single test is not enough.
• Threshold not reached → if the panelist misses the highest level, the BET is estimated above the range (highest level × √2, calculation type all-wrong) and the test isn't passed. In that case it's worth extending the series toward higher concentrations and repeating.

Where you see the results

Results are only computed when you close the tasting. While it isn't closed, you'll see the notice "Results are calculated automatically when you close the tasting."

Once the tasting is closed, the detail shows the Calibration results table with one row per panelist and these columns:

Why it matters

• It confirms that your panel has quantified sensitivity, not just "experience."
• It's the piece that qualifies the selected level and, together with a passed basic taste test in the last 6 months, the expert level, which lets you sign dossiers backed by ISO 8586 methodology.