不同炒制时间对燕麦挥发性风味物质形成的影响

采用顶空固相微萃取-气相色谱-质谱联用技术对不同炒制时间的燕麦挥发性风味物质进行测定分析，初步建立脂肪氧化程度与燕麦风味物质形成的关联性。结果表明：在整个炒制过程中，燕麦中烃类、醛类、醇类物质的含量随炒制时间的增加呈先增加后减少的趋势，而吡嗪类物质含量在炒制25 min后显著增加。聚类分析结果表明，炒制前期(≤15 min)与炒制中后期(≥25 min)的燕麦风味区分明显。相对香气活度值、主成分分析表明，炒制前期的特征风味物质以醛类为主，包括癸醛、(E)-2-壬烯醛、壬醛、苯甲醛等，呈果香、甜香、花香、弱油脂香；而炒制中后期的特征风味物质以吡嗪类、醛类为主，呈焦香味、果香味。炒制初期燕麦中不饱和脂肪酸质量分数由84.41%降至81.72%,炒制中后期脂质氧化产物逐渐增多、氧化程度逐渐加深，茴香胺值从0.73升高到4.49后开始降低，硫代巴比妥酸值从0.023 mg/kg升高到0.039 mg/kg后保持不变，炒制前中期(<35 min)脂肪氧化程度与醛类等重要风味物质的含量呈正相关。

Effect of different frying time on the formation of volatile flavor substances in oats

Headspace solid phase microextraction, gas chromatography-mass spectrometry were used to determine and analyze the volatile flavor compounds of oat at different roasting time, and the correlation between lipid oxidation degree and the formation of oat flavor compounds was preliminarily established. The results showed that the contents of hydrocarbons, aldehydes and alcohols increased first and then decreased with the increase of roasting time, while the contents of pyrazines increased significantly after 25 min of roasting. Cluster analysis showed that the oat flavor in early stage of roasting (≤15 min) and middle and late stage of roasting (≥25 min) was significantly different. Relative aroma activity value and principal component analysis showed that aldehydes were the main characteristic flavor substances in the early stage of roasting, including decaldehydes, (E)-2-nonenal, nonenal, benzaldehyde, etc., showing fruity, sweet, floral and weak oil aroma. The characteristic flavor substances in the middle and late stage of roasting are mainly pyrazines and aldehydes, showing burnt flavor and fruit flavor. The unsaturated fatty acid content of oat decreased from 84.41% to 81.72% in the early stage of roasting, the lipid oxidation products increased gradually and the oxidation degree deepened gradually in the middle and late stage of roasting, the aniside value began to decrease after increasing from 0.73 to 4.49, and the thiobarbituric acid value remained unchanged after increasing from 0.023 mg/kg to 0.039 mg/kg. The degree of fat oxidation was positively correlated with the content of aldehydes and other important flavor substances before and during roasting (< 35 min).