Long-Chain n-3 PUFA Content and n-6/n-3 PUFA Ratio in Mammal, Poultry, and Fish Muscles Largely Explain Differential Protein and Lipid Oxidation Profiles Following In Vitro Gastrointestinal Digestion.

Scope: Muscle food characteristics (fatty acid profile, heme-Fe, intrinsic antioxidants) that relate to the formation of (patho)physiological oxidation products during gastrointestinal digestion are investigated.

Methods And Results: Muscles (n = 33) from 18 mammal, poultry, and fish species, of which some are mixed with lard to standardize their fatty acid profile, are digested in vitro. Lipid oxidation is assessed by thiobarbituric reactive substances (TBARS), n-3 PUFA derivative 4-hydroxy-2-hexenal and propanal, n-6 PUFA derivative 4-hydroxy-2-nonenal and hexanal, and protein oxidation by carbonylation. Digests of n-3 PUFA-rich fish demonstrated the highest n-3 PUFA oxidation, whereas digests of various poultry and rabbit muscles showed highest n-6 PUFA oxidation, which correlated significantly with the n-6/n-3 PUFA ratio. Without lard addition, lipid oxidation is significantly higher in chicken and pork loin digests versus beef and deer digests, whereas the opposite occurred when these muscles are mixed with lard. Protein carbonylation correlates significantly with levels of TBARS and the sum of hydroxy-alkenals in digests. The n-6/n-3 PUFA ratio correlates well with the 4-hydroxy-2-nonenal/4-hydroxy-2-hexenal ratio in digests.

Conclusions: Muscular fatty acid profiles largely explain type and extent of lipid and protein oxidation during gastrointestinal digestion. Red meat only stimulates oxidation when digested with specific fat sources.