Review: Subjective pork quality evaluation may not be indicative of instrumental pork quality measurements on a study-to-study basis

Since adoption of National Pork Producers Council (NPPC) subjective pork quality standards almost 20 yr ago, there have been limited investigation of the correlation and relationship between subjective pork quality and instrumental measurement. The objective of this review was to investigate the correlation between subjective evaluation of color and marbling with the instrumental measurement of color and i.m. lipid composition. A database of 454 population or treatment group means from 101 peer-reviewed studies representing 30 affiliations (by corresponding author of publication) was used. This database was used to calculate summary statistics and Pearson correlation coefficients, as well as create prediction equations using simple linear regression and multiple linear regression modeling. Subjective color determined with NPPC (NPPC, 1999) color standards was weakly correlated (r ≤ |0.35|; P < 0.01) with instrumental L*, a*, and b* when measured with a Minolta colorimeter. Marbling evaluated using NPPC (1999) marbling standards was moderately correlated (r = 0.48; P < 0.0001) with i.m. lipid percentage. The results of this review indicate the need for the meat science research community to acknowledge that NPPC color and marbling scores may differ significantly on a study-to-study basis when attempting to standardize with Minolta colorimeter readings and i.m. lipid percentage with various extraction procedures. In conclusion, this review focused on the correlations of subjective pork evaluation with instrumental pork measurements since the creation of the NPPC standards for subjective evaluation. This review emphasizes the need to better understand and interpret methodology when making study-to-study comparisons in regard to evaluation of pork quality.