HCA Dosing Bench¶

Version 1 · Disclaimer

Three tabs that do the arithmetic in the precursor system page (§3–§5, §9, §12) and the stock solutions page (§1–§3). Dose goes from a target ethyl-phenol concentration to the precursor mass, the millilitres of stock and a dated, staged schedule, or backwards from planned additions to the expected range against thresholds, the traditional gueuze range, the spike targets and the overshoot ceiling. Stocks is make-up arithmetic for the 50 % ethanol HCA stocks, the green-coffee slurry and the zinc stock, with a copyable label and use-by. Sanity checks the largest single dose against the Harris 2015 growth-lag and MIC figures and counts dosing events against sampling events.

What the bench does not know: the conversion efficiencies are working assumptions (50 % for free acids in active fermentation, 3–5 % for bound chlorogenic; Med), the per-acid split is a guess, and the thresholds are literature typicals. The taste gate at each sampling point is the control. It is a planning aid; 4-EP overshoot is irreversible except by dilution, so err low.

The bench¶

It also runs on its own at /assets/apps/hca-bench/index.html if the frame above is awkward on a phone.

The model¶

Each pathway is two steps, PAD then VPR, and the mass ratio of precursor to ethyl phenol is fixed by the molar masses:

For a target \(T\) (µg/L), batch \(V\) (L), wort baseline \(B\) (mg/L of free acid), efficiency \(e\) and ratio \(r\):

Caffeic via green coffee: one capsule is ~110 mg chlorogenic acid, so 4-EC per capsule per 5 L at 3–5 % bound efficiency is 110 / 2.564 × 0.03–0.05 / 5 = 257–429 µg/L, the "~250–400" the stock page quotes. Capsules are rounded up to halves and never split finer (§12.4).

The schedule follows §12.4: funk-forward contexts put at most 30 % of the p-coumaric budget at Day 0 and split the rest across three sampling points at the cadence set, taste-gated from the second; ferulic is scheduled only if the 4-EG target exceeds what the baseline delivers, and never as a bolus; capsules go whole or half at sampling points. Ester-forward takes the full Day-0 dose and one 5 mg per 5 L top-up at secondary week 2. The donor (§5 case C) and rescue (§9) programmes are fixed and scaled by volume. The bench warns when a scheduled dose falls under the 2 mg per 5 L syringe-resolution floor or when the programme outruns the six-month stock use-by.

What the bench shows that the pages do not say outright¶

Test the wiki's own numbers and a tension appears. Use case A in §5, 20–25 mg p-coumaric per 5 L, predicts 1,500–1,900 µg/L 4-EP at 50 % efficiency, above the §3 spike target of 600–1,000 and near the top of the traditional range; the two agree only at roughly 25–35 % efficiency or with a baseline near zero. The same happens to ferulic: a 2–8 mg/L wort baseline at 45 % would alone give 700–2,800 µg/L 4-EG against a traditional 100–800, which is why the bench treats the baseline figure with suspicion and says so when the wort alone predicts more than the range. The efficiency sliders exist so that the reading you adopt is explicit; the numbers are not hidden.

Stocks¶

Stock make-up follows the stock solutions page exactly: 100 mg into 5.1 mL of ~98 % ethanol then 4.9 mL distilled water for 10 mL at 10 mg/mL (0.51 × volume of ethanol, the rest water); 20 mg/mL dissolves, 40 does not. Use-by six months at 4 °C; the figure the bench gives for warmer storage is a Q10 = 2 rule of thumb (Low), not data. Zinc is 0.1–0.2 mg/L once, from a 1 mg/mL stock made from one 15 mg zinc sulfate tablet in 15 mL.

Sanity¶

Harris et al. 2015: growth lag around 4 mM for ferulic (~780 mg/L) and p-coumaric (~660 mg/L), MIC from 8 mM upward for p-coumaric, 12–14 mM for ferulic, 25–30 mM for caffeic. A 25 mg spike into 25 L is 1 mg/L, 0.006 mM, three orders of magnitude below the lag. Substrate toxicity is not a reason to micro-dose; flux matching, residence-time losses and overshoot control are. The airlock budget counts dosing events that are not co-located with a sampling point, because the 4–6 week sampling lift is already the calibrated oxygen dose.