Protein Calc — sequence-derived nitrogen factors

57 commodities · 136 verified proteins · a nitrogen-to-protein factor (k) computed from real amino acid sequences, not 1931 convention.

"The nitrogen-to-protein factor is a guess from 1931 — for pea, rice and beef trim it overstates protein by 10-15%, and the fix is public sequence data, arithmetic, and a script."

Sequence k vs conventional factor

CommodityClassConv kSeq k BiasCovTier

Bias = how much the conventional factor overstates protein vs the sequence-derived k. Red = overstates, green = understates. Coverage = share of protein accounted for by verified sequences (the remainder is assumed to resemble the mixture — see --sensitivity for the quantified bound).

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True-protein calculator

Enter your lab numbers (% w/w). True protein = (total N − NPN) × k, where k is the sequence-derived factor for the selected commodity.