North American Beef Tenderness Survey 2011-2012: benchmarking tenderness and sample shipping procedures

Fifty-four stores in 30 U.S. cities were sampled from June 2011 through May 2012 to benchmark beef tenderness at retail, as assessed by Warner-Bratzler shear force (WBSF). Top loin (Longissimus dorsi; n = 980) and sirloin (Gluteus medius and Biceps femoris; n = 860) steaks were collected at random (Quality Grade and brand) and shipped via overnight delivery to Colorado State University. From June 2011 through November 2011, North American Beef Tenderness Survey (NABTS) Period 1, samples were shipped fresh and then frozen. Mean WBSF values during Period 1 were 2.9 and 3.5 kg for top loin and sirloin steaks, respectively. Frequencies of steaks classified as tough (WBSF ≥ 4.4 kg) were 8.6% and 17.7% for top loin and sirloin steaks, respectively. When shipped fresh, a disproportionately high frequency (16.9%) of top loin steaks had WBSF ≤ 2.0 kg, representing a deviation from previous works. Two trials were conducted to assess the effect of freezing, retail display, and shipping on WBSF and slice shear force (SSF) of beef top loin steaks. Freezing, retail display, and shipment reduced WBSF by 0.4, 0.3, and 0.0 kg during Trial 1, and by 0.4, 0.3, and 0.1 kg during Trial 2. Slice shear force was lower (P < 0.05) in steaks exposed to shipping conditions during Trial 1; however, this difference was not observed in Trial 2. Shipping decreased the frequency of steaks categorized as tough (SSF ≥ 20.0 kg) from 11.1 to 5.7% and from 30.5 to 28.6%, during Trial 1 and 2, respectively. During Trial 1, WBSF indicated that shipping increased incidence of tough samples from 0.0 to 3.8%, but this trend was reversed during Trial 2 when shipping reduced incidence of tough samples from 13.0 to 5.6%. Coefficients of variation for treatment effects suggested variance remained unchanged (± 2.0%), with respect to shear force values. However, mean values were reduced as a result of shipping conditions. These findings dictated a change in NABTS protocol from December 2011 through May 2012 (Period 2), during which time samples were shipped frozen. Mean WBSF values were 3.4 and 4.0 kg for top loin and sirloin samples, respectively. Frequencies of steaks classified as tough were 14% and 23.5% for top loin and sirloin steaks, respectively. These findings suggest that freezing samples before shipment may influence shear force of steaks collected at the retail level. These data should be considered when evaluating beef tenderness surveys and in the design of future works.