Core Formula
IFI(c, m) = 1,000 Γ ECβ β(ref) / ECβ β(c)
A compound with an ECβ β ten times lower than the reference (i.e., ten times more potent) scores IFI 10,000. A compound ten times less potent scores 100. The reference compound always scores exactly 1,000.
Seven Sub-Scales
Heat
Receptor: TRPV1
Measures capsaicinoid potency as ECβ β ratio relative to capsaicin. The original Scoville dimension, receptor-normalized. IFI-H 1,000 = capsaicin baseline.
Reference: Capsaicin = IFI H 1,000
Sweet
Receptor: TAS1R2/TAS1R3
Sweetness intensity relative to sucrose perception threshold. Engineering TAS1R2/TAS1R3 heterodimers and downstream GΞ± gustducin cascades lifts IFI-S scores into novel sweetness territory.
Reference: Sucrose (2% solution) = IFI S 1,000
Umami
Receptor: TAS1R1/TAS1R3 + mGluR1
Savory/umami intensity measured against MSG reference. Dual-axis: TAS1R1/TAS1R3 taste receptor and mGluR1 (metabotropic glutamate receptor). Synergy with GMP/IMP ribonucleotides amplifies scores.
Reference: MSG (0.1% solution) = IFI U 1,000
Bitter (Zero)
Receptor: TAS2R38
Inverse bitter index β higher scores mean less bitter perception. TAS2R38 is the dominant bitter receptor in brassica crops; suppression via CRISPR raises IFI-B toward 1,000 (zero bitter). Reported as % bitterness reduction in consumer products.
Reference: Phenylthiocarbamide (PTC) = IFI B 1,000
Kokumi
Receptor: CaSR
Kokumi 'mouthfulness' intensity. CaSR (calcium-sensing receptor) responds to Ξ³-glutamyl peptides, amplifying richness and continuity of flavor. Engineering garlic/onion CaSR pathways into other crops creates novel textural flavors.
Reference: Ξ³-Glu-Val-Gly peptide = IFI K 1,000
Cool Burn
Receptor: TRPM8 + TRPV1
Biphasic thermal sensation: the ratio of TRPM8 (cooling) activation to TRPV1 (heat) activation. An IFI-C ratio of 1.0 means equal cooling and heat. Values > 1 skew cool; values < 0.3 are primarily heat.
Reference: Menthol (TRPM8) + Capsaicin (TRPV1) = IFI C 1,000
Pungent (TRPA1)
Receptor: TRPA1
TRPA1 channel activation via allyl isothiocyanate and related electrophilic compounds. Distinct from TRPV1 heat β produces sharp, nose-clearing pungency characteristic of mustard and wasabi. Engineering mustard pathway genes into novel hosts creates plant-based pungency.
Reference: Allyl isothiocyanate (AITC) = IFI P 1,000
Reference Profile: D.N.R.
Design Null Reference
D.N.R. is our internal reference strain β a Capsicum chinense construct with no IFI-S, IFI-U, IFI-B, IFI-K, IFI-C, or IFI-P engineering. Its IFI-H is β 4,200, placing it above pure capsaicin (IFI-H 1,000) due to Pun1 variant stacking. D.N.R. anchors the heat axis for all comparative measurements.
IFI-H
4,200
IFI-S
β
IFI-U
β
IFI-B
β
IFI-K
β
IFI-C
β
IFI-P
β
Timeline
Scoville Organoleptic Test
Wilbur Scoville's dilution-to-threshold test. Capsaicin = 16,000,000 SHU. Useful, but single-dimensional and human-panel dependent.
HPLC replaces panels
High-performance liquid chromatography quantifies capsaicinoids directly. Scoville units become calculated, not tasted. Precision improves; dimensionality stays at one.
Taste receptor cloning
TAS1R and TAS2R receptor families cloned. The molecular basis of sweet, umami, and bitter taste established. A multi-receptor framework becomes possible.
TRPV1 atomic structure
Capsaicin binding site mapped on TRPV1. ECβ β values can now be calculated from structure alone, enabling receptor-normalized comparison across compounds.
ECβ β normalization proposed
Receptor-specific ECβ β ratios as a unified flavor scale. The seed of IFI: if we normalize by receptor sensitivity, any compound on any receptor can share a common axis.
Iyengar Flavor Index published
IFI-H through IFI-P: seven sub-scales, one formula, full-spectrum flavor quantification. First applied to engineered Capsicum constructs; extended to 8 crop platforms.