Fatty acid composition of intramuscular fat and odour-active compounds of lamb commercialized in northern Spain

Abstract

Muscle fatty acid composition and odour-active compounds released during cooking were characterized in lamb chops (Longissimus thoracis et lumborum, n = 48) collected at retail level in northern Spain. Lamb samples were classified in two groups according to their 10 t/11 t-18:1 ratio: ≤1 (10 t-non-shifted, n = 21) and >1 (10 t-shifted, n = 27). Higher n-3 polyunsaturated fatty acid, vaccenic (11 t-18:1) and rumenic acid (9c,11 t-18:2), and iso-branched chain fatty acid contents were found in non-shifted lamb samples while n-6 polyunsaturated fatty acid, internal methyl-branched chain fatty acid, and 10 t-18:1 contents were greater in shifted samples. Regardless the fatty acid profile differences between lamb sample groups, odour-active compound profile was very similar and mostly affected by the cooking conditions. Overall, the main odour-active compounds of cooked lamb were described as "green", "meaty", "roasted", and "fatty" being methyl pyrazine, methional, dimethyl pyrazine, and dimethyl trisulphide the main odour-active compounds. Aldehydes and alcohols were the most abundant volatiles in all samples, and they were mostly originated from the oxidation of unsaturated fatty acids during cooking.

Keywords: Lipid oxidation; Polyunsaturated fatty acids; Sheep; Survey; Volatile compounds.