Effects of Cooking Methods on Fatty Acid Composition and Volatile Substances in Oven-Roasted Lamb Chops

Roasted lamb chops were prepared by superheated steam roasting (SSR) and direct roasting (DR). To explore the formation mechanism of flavor substances, descriptive sensory analysis (DSA), an electronic nose (E-nose) system, head-space solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), and gas chromatography-olfactometry (GC-O) were employed to analyze the sensory properties, fatty acid composition and volatile compounds of the SSR and DR samples. The DSA and E-nose results consistently revealed variations in aroma profiles between the two samples. The DR sample showed stronger roasted, fatty, and mutton-like aroma (P < 0.05). A total of 44 volatile compounds were identified from both samples. The contents of aldehydes, alcohols, and nitrogen-containing compounds in the DR sample were higher than those in the SSR sample. Totally 35 aroma-active compounds were identified by aroma extract dilution analysis (AEDA) combined with GC-O analysis, among which, decanal, hexanal, octanal, nonanal, (E,Z)-2,6-nonadienal, (E,E)-2,4-decadienal, (E,E)-2,4-nonadienal, 1-octen-3-one, 3-octen-2-one, 2-nonanone, heptanoic acid, 2-methylpyrazine, 3-(methylthio)propanal, benzothiazole, and 2-pentylfuran were the major ones. The types of aroma-active compounds in the two samples were similar, but their flavor dilution (FD) factors were different. Compared with the SSR sample, the content of total fatty acids in the DR sample significantly increased (P < 0.05). The content ratio of polyunsaturated fatty acids to saturated fatty acids (PUFA/SFA) in the DR sample was 40.66%, indicating higher nutritional value. Pearson’s correlation analysis showed that the oxidative degradation of unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, and eicosenoic acid was closely related to the formation of the characteristic flavor in roasted lamb chops.