Open AccessEvaluation of Beef Steak Exudate Differing in Quality Grade and Post-Mortem Aging Time
Author(s) -
K. R. Wall,
C. R. Kerth,
Zena M Hicks,
D. H. Tucker
Publication year - 2019
Publication title -
meat and muscle biology
Language(s) - English
Resource type - Journals
ISSN - 2575-985X
DOI - 10.22175/mmb.10803
Subject(s) - exudate , absorbance , dilution , chemistry , loin , chromatography , food science , zoology , botany , biology , physics , thermodynamics
ObjectivesEvaluate absorbance and metabolite differences of beef exudate from raw beef steaks differing in quality grade and post-mortem aging time.Materials and MethodsUSDA Select (SE; n = 18) and USDA Choice (CH; n = 18) beef strip loins were aged for 7d, cut into 2.54 cm thick steaks, and randomly assigned a post-mortem aging duration of either 10 or 20d post-mortem (n = 72 total). Steaks were individually packaged on d7 and frozen on the assigned day at –20°C until time for analysis. Steaks were thawed for 24h at 4°C before 2 mL of exudate was collected from each bag on removal of the steak. The exudate was frozen at –80°C until further analysis. For analysis of absorbance, 0.5 mL of thawed exudate was diluted with 4.5 mL ultra-pure water and centrifuged. Then, 200 μL of the dilution was pipetted in triplicated onto a 96 well plate. Absorbance was read at a range of 350–700nm wavelengths. A dilution of 1:20 beef exudate: ultra-pure water was filtered and used for metabolite analysis. Using a HILIC column, 5 μL were injected into an organic mobile phase gradient and analyzed using an Agilent 6545 LC/MS-QTOF in positive mode. Data were analyzed using a two-factorial design with quality grade and post-mortem day of aging as fixed effects with an α of 0.05. Loin was included as a random effect. Least squares means, correlations, and principal component analysis were used to discriminate data.ResultsCH exudate had greater (P 0.05) were detected at all other wavelengths analyzed between quality grade. Post-mortem aging had no effect (P > 0.05) on wavelength absorbance. Of the total metabolites present (n = 33) in the samples, no differences (P > 0.05) were observed among fixed effects. Only three metabolites exhibited a twofold change in expression, observed as a downregulation from SE to CH exudate. With age, nearly two-thirds of the metabolites (n = 19) tended to increase in intensity. Tritriacontyl octacosanoate was unique to SE exudates.ConclusionBeef exudate tends to be influenced by quality grade more than post-mortem aging duration. Accordingly, exudate samples from raw steaks may be classified by quality grade no matter the duration of aging time.