Dry-ageing impacts on meat quality, oxidative stability, and release of free amino acids in striploins from dairy crossbred yearling and 2-year-old steers

This study determined the impacts of dry-ageing on meat quality, oxidative stability, and release of free amino acids (FAAs) in striploins from dairy-crossbred yearlings and 2-year-old steers (n = 12 each group) over 21 days of in-bag dry-ageing. Dry-ageing increased weight losses, with higher % drying rates in yearling meat during dry-ageing, likely due to the smaller loin size and lower intramuscular fat content (P < 0.05). Yearling meat showed greater (P < 0.05) decreases in moisture content, but both meats reached similar moisture levels by day 21. pH values increased with dry-ageing with variations at different ageing times. Dry-ageing reduced a*, b*, and chroma while increasing L* and hue angles on day 21 (P < 0.05), likely due to dehydration and lipid oxidation (higher TBARS, P < 0.05) after 14 days, especially in yearling meat. The decreased levels (P < 0.05) of some monounsaturated fatty acids and conjugated linoleic acid cis-9, trans-11 were likely linked with lipid oxidation. Total levels of FAAs and essential amino acids increased significantly, especially within the first 7 days, with distinct patterns between the two meats. Dry-aged yearling meat contained more FAAs associated with sweat taste (e.g., glutamine and glycine) and fewer FAAs associated with bitter taste (e.g., phenylalanine and tyrosine). Carnosine levels varied and significantly increased after 21 days. Dry-ageing demonstrated distinct effects on dehydration, lipid oxidation, and release of FAAs in meat from yearlings compared with 2-year-old steers, which can be tailored to develop high-quality beef products with unique flavours.