The extent to which modification of Warner-Bratzler shear force (WBSF) dete
rminations, relating to storage and preparation of the meat, aperture of th
e V-shaped cutting blade and shearing velocity, improve the relationship wi
th sensory tenderness perception of pork was studied. Additionally four on-
line methods: pH1, FOP1 (light scattering), PQM1 (conductivity) and DDLT (D
ouble Density Light Transmission), were evaluated for their ability to pred
ict tenderness. Sensory tenderness evaluation was conducted on 120 frozen (
at -18 degrees C for several months) samples of m. longissimus thoracis et
lumborum. After overnight thawing, the meat was grilled to an internal temp
erature of 74 degrees C and scored on an eight-point scale, from extremely
tough to extremely tender. The standard WBSF procedure (protocol A) consist
ed of heating fresh meat samples (stored for 48 h at 4 degrees C post slaug
hter) at 75 degrees C for 50 min, cooling in cold tap water for 40 min, tak
ing cylindrical cores parallel to the fibre direction, and shearing at a ve
locity of 200 mm/min with a blade aperture of 60 degrees. For the predictio
n of sensory tenderness, the WBSF standard procedure (protocol A) showed th
e lowest variance (R-2 = 15%) and the highest standard error of the estimat
e (SEE = 0.97 N) compared to the other WBSF protocols. A decrease in sheari
ng velocity, from 200 to 100 mm/min and, a replacement of the cutting blade
with an aperture of 60 degrees by one with an aperture of 30 degrees led t
o improvements of R-2 (respectively, 19% vs. 13% and 47% vs. 23%) and SEE (
respectively, 0.93 N vs. 0.97 N and 0.80 N vs. 0.97 N) and thus were better
predictors of tenderness. A blade aperture of 30 degrees instead of 60 deg
rees also led to considerably lower WBSF values (22.1 N vs. 30.0 N). Freezi
ng, frozen storage and thawing of the meat, prior to WBSF measurement, resu
lted in higher shear force values (32.7 N vs. 28.7 N) and a better predicti
on of tenderness, R-2 (25% vs. 15%) and SEE (0.94 N vs. 1.00 N). Furthermor
e, preparing the frozen stored meat for WBSF determination in the same way
as for the sensory evaluation, namely grilling instead of boiling, led to h
igher WBSF values (35.5 N vs. 32.7 N) and a further improvement in the pred
iction of tenderness (R-2 = 31% vs. 25% and SEE = 0.90 N vs. 0.94 N). From
the on-line instruments: pH, FOP and PQM, pH was best in predicting tendern
ess. Linear regression with tenderness as dependent variable and the on-lin
e techniques as independent variables revealed the following R-2: 16, 8, 8
and 10% and SEE: 0.96, 1.01, 1.01 and 1.00 N for, respectively, pH1, FOP1,
PQM1 and DDLT. Thus, the classical instruments and the DDLT technique, whic
h is analogous to the CGM (Capteur Gras/Maigre), an officially accepted car
cass grading apparatus in France and Belgium, are not good predictors of te
nderness. (C) 1999 Elsevier Science Ltd. All rights reserved.