2025-03-122025-03-122025-03-11Piao, D. (2025). Modified Krzywicki’s equations to quantify myoglobin forms on meat surfaces. Meat and Muscle Biology. https://doi.org/10.22175/mmb.18338https://hdl.handle.net/20.500.14446/345863Krzywicki’s equations to determine myoglobin forms on meat surfaces allow quantification without creating myoglobin form standards. However, Krzywicki’s equations can result in unrealistic estimations of the percentage numbers of the myoglobin forms. In this study, we revisited Krzywicki’s individual equations of [Oxy]%, [Deoxy]%, and [Met]% based on tissue optics and reexamined the practice of deriving [Oxy]% indirectly using [Deoxy]%, and [Met]%. In addition, the use of baseline correction at 730 nm in myoglobin quantification equations was also evaluated. The modified Krzywicki’s equations were tested on 44 loins (longissimus lumborum, n = 22; psoas major, n = 14; semitendinosus muscles, n=8). Testing on colorimeter measurements indicated that Krzywicki’s equation for directly estimating [Oxy]% could be sensitive to the baseline reference projected for 730 nm. A new algorithm converting the spectral reflec- tance to spectral absorption outperformed that which converts the spectral reflectance to reflex attenuance, in implementing Krzywicki’s equations. The modified Krzywicki’s equations performed better, with or without including 730 nm, in spe- cifically resolving a more realistic increase of the [Met]% during the retail display. For example, the new algorithm applied to psoas major muscles revealed a pronounced rapid increase of the [Met]% as the chroma reduced to ∼30, compared to a steady increase of the [Met]% in longissimus lumborum muscles at similar numbers of chroma. The results suggest that modified Krzywicki’s equations provide a more realistic estimation of the percentage numbers of myoglobin forms on steak surfaces than the original equations.application/pdfThis material has been previously published. In the Oklahoma State University Library's institutional repository this version is made available through the open access principles and the terms of agreement/consent between the author(s) and the publisher. The permission policy on the use, reproduction or distribution of the material falls under fair use for educational, scholarship, and research purposes. Contact Digital Resources and Discovery Services at lib-dls@okstate.edu or 405-744-9161 for further information.10.22175/mmb.18338Articlemyoglobinmyoglobin formsoxymyoglobindeoxymyoglobinmetmyoglobinKrzywickicolorimeterspectral reflectancediffuse reflectance2575-985X