焙烤对宁夏滩羊羊脂水分分布和关键性香气成分的影响

以宁夏盐池滩羊肉羊脂作为研究对象，运用低场-核磁共振技术研究烤制过程中羊脂水分分布及迁移规律。采用顶空固相微萃取提取不同烤制过程中羊脂挥发性成分，并结合气相色谱-质谱、电子鼻进行分析。结果表明：羊脂L*随着烤制时间的延长而下降，a*、b*随烤制时间的延长呈上升趋势。羊脂烤制过程中弱结合水的相对含量呈增加趋势，而不易流动水相对含量呈下降趋势。T23随烤制时间的延长呈明显减小趋势，说明随烤制进行水分子与大分子物质结合更紧密。在10?个烤羊脂样品中共检出78?种挥发性成分，其中醛类12?种、醇类11?种、酮类9?种、烯烃类4?种、酸类10?种、酯类12?种、杂环类12?种、其他物质8?种。己醛、壬醛、1-辛烯-3-醇、3-羟基-2-丁酮、7-甲基-3-亚甲基-1,6-辛二烯和甲苯普遍含量较高。酯类物质主要存在于羊脂烤制初期，而杂环类化合物，特别是吡嗪类化合物主要存在于烤制后期。电子鼻数据的主成分分析结果表明，烤制过程对羊脂中的氮氧化物、芳香族化合物、有机硫化合物、醇类有显著影响，对烷烃、氢化物和氨类化合物影响不大。

Effect of Roasting on Moisture Migration and Key Aroma Compounds of Mutton Tallow

Moisture distribution and migration in the tallow of Tan sheep from Yanchi, Ningxia roasted for different periods were analyzed by low field-nuclear magnetic resonance (LF-NMR). Head space solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and an electronic nose (E-Nose) were used to analyze the volatile components of mutton tallow. The results showed that the L* value of mutton tallow decreased, and the a* and b* values increased with roasting time. The percentage of weakly bound water showed an increasing trend, and the percentage of immobile water showed a decreasing trend. The relaxation time T23 showed a significantly decreasing trend with roasting time, indicating tighter binding of water molecules to macromolecular substances. A total of 78 volatile compounds were detected in 10 samples, including 12 aldehydes, 11 alcohols, 9 ketones, 4 alkanes, 10 acids, 12 esters, 12 heterocyclic compounds and 8 other compounds, with hexanal, nonanal, 1-octene-3-ol, 3-hydroxy-2-butanone, 7-methyl-3-methylene-1,6-octadiene and toluene being the major ones. Esters were found mainly in the early stage of roasting, while heterocyclic compounds, especially pyrazine compounds, mainly in the late stage. Principal component analysis performed on E-nose data showed that different roasting periods had significant effects on the contents of nitrogen oxides, benzenes, organic sulfur compounds and alcohols in mutton tallow, but little effect on alkanes, hydrides and ammonia compounds.