Quantitative Mass-Balance Determination of Kavalactone Transfer, Partitioning, and Chemotype Behavior in American-Grown Kava (Piper methysticum) Beverages

Kava beverages are consumed as aqueous suspensions, yet potency is conventionally estimated from solvent extraction of raw root rather than measured in the beverage itself; mainland American-grown kava remains largely uncharacterized. Fresh-frozen roots of three American-grown Piper methysticum cultivars (Kali-Hiwa, Kali-ISA, Kali-Rogu) were prepared by a standardized short warm-water extraction (SWWE), with identity confirmed as authentic P. methysticum by HPTLC; one characterized lot per cultivar was extracted in process triplicate. Total beverage kavalactones were quantified using a validated difference estimator (KL₀ − KLm, input minus residue) and compared against direct HPLC analysis of recovered dehydrated beverages, giving a mean absolute relative difference of 2.8% (SD 2.2%; 95% CI 1.2–4.4%; n = 10). SWWE extracted an average 85.1% of total kavalactones, producing 188⁠–⁠452 mg per 125 mL serving. Delivery was estimated to be predominantly particle-associated (78.7% Kali-ISA, 97.2% Kali-Hiwa, 85.3% Kali-Rogu). Bulk beverage chemotypes matched each cultivar’s canonical profile within measurement resolution, whereas Kali-Hiwa and Kali-Rogu each expressed a distinct dihydrokavain- and kavain-enriched non-particulate chemotype (Kali-Rogu p = 0.005; Kali-Hiwa p = 0.375, provisional); Kali-ISA alone remained consistent across phases. Mass balance provides a beverage-state basis for quantifying realized kavalactone delivery in intact suspensions, supporting per-serving labeling and batch comparability; partition estimates are model-derived and exploratory.