2:00 pm - 3:00 pm
4-10C Agriculture/Forestry Centre, University of Alberta, Edmonton AB
Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Katie Pedgerachny. This seminar is open to the general public to attend.
Zoom Link: https://ualberta-ca.zoom.us/j/96103787981
MSc with Dr. Heather Bruce.
Thesis Topic: Relationships between Canadian beef grade and intramuscular collagen characteristics in bovine m. longissimus lumborum
Abstract:
Consumers’ decisions to purchase beef are determined by various factors, including meat appearance and anticipated and experienced eating satisfaction. While there are different contributions of each intramuscular component to meat quality, intramuscular connective tissue (IMCT) impacts beef tenderness as “background toughness.” IMCT is primarily composed of the protein collagen, which increases in crosslink complexity as animals age. Youthful animals primarily have immature divalent collagen crosslinks and Ehrlich Chromogen which are temperature labile. However, as animals age, the divalent crosslinks transition into the mature trivalent crosslink, pyridinoline, which provides increased stability to the collagen structure throughout muscle. This results in declining collagen heat solubility as well as increased Slice Shear Force (SSF) of cooked meat. For consumers, this is undesirable for beef, as it requires extended cooking periods to allow the collagen to degrade and gelatinize. Current research has reported the impacts of pyridinoline and Ehrlich Chromogen on beef toughness; however, the effects of divalent collagen crosslinks are less understood.
The objective of this study was to evaluate the relationship between beef quality grade, toughness as determined by SSF, and collagen characteristics, specifically collagen solubility and collagen divalent and trivalent crosslink quantification. Longissimus lumborum m. steak samples were randomly collected from beef carcasses (Canada AA, n= 101; Canada AAA, n= 500) and aged for 14 d. After, cooked tenderness was measured using SSF and samples were categorized into tender (SSF=0-19.9 kg), intermediate (SSF=20.0-39.9 kg), and tough (SSF>40.0 kg) subcategories. Collagen heat solubility was measured on a frozen uncooked portion from each sample, and categorized as high or low collagen solubility, and related to collagen divalent and trivalent crosslinks which were quantified utilizing a novel technique.
Results showed that muscles from Canada AA carcasses had greater soluble collagen, greater mean slice shear force, and less insoluble collagen than muscles from Canada AAA carcasses. However, there were no differences due to collagen solubility or tenderness category. Ehrlich Chromogen, pyridinoline, lysinonorleucine, hydroxylysinonorleucine, 5,5’-dihydroxylysinonorleucine, and deoxypyridinoline concentrations were unaffected by and unrelated to, respectively, quality grade and collagen solubility percentage. As the longissimus lumborum muscle used in this study is a tender cut of meat located in the loin area resulting in reduced connective tissue, future research should focus on differing locations of muscle and characterization of divalent crosslinks variation with animal age to identify the relationship between collagen crosslink type and beef toughness.
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