红外焙炒对菜籽油风味的影响机制Effect mechanism of infrared roasting on the flavor of rapeseed oil

在不同温度（90、110、130、150、170 ℃）下红外焙炒油菜籽，经液压压榨制备菜籽油，通过油脂氧化、硫苷化合物降解反应和美拉德反应研究红外焙炒对菜籽油风味的影响机制，并与传统炒籽（170 ℃）进行比较。结果表明，红外焙炒的菜籽油较传统炒籽的菜籽油风味有显著改善，油脂味和辛辣刺激味较后者更轻，而烤香味相对更浓，同时多环芳烃种类和含量也较少。对冷榨菜籽油（由未经任何处理的油菜籽压榨制得）加热3 h，油脂热降解的标志性化合物（E,E）-2,4-庚二烯醛和（E,E）-2,4-癸二烯醛的含量分别增加3.86倍和6.28倍。随着焙炒温度的升高，红外焙炒处理的脱脂油菜籽中硫苷化合物含量从30.73 mg/kg减少至15.23 mg/kg，游离氨基酸总量从未处理的25.61 mg/100 g减少至15.82 mg/100 g，还原糖含量从7.61 mg/g减少至2.29 mg/g。红外焙炒对菜籽油风味的影响机制主要为不饱和脂肪酸降解成为中短链醛与烯醛类化合物，硫苷化合物降解生成异硫氰酸和腈类化合物，以及美拉德反应生成吡嗪、呋喃类化合物。 The rapeseed was infrared roasted at different temperatures（90，110，130，150，170 ℃）, and hydraulic pressed to prepare rapeseed oil. The effect mechanism of infrared roasting on flavor of rapeseed oil was studied through the oil oxidation, degradation of glucosinolate compounds and Maillard reaction, and compared with the traditional roasting(170 ℃). The results showed that the flavor of rapeseed oil from rapeseed roasted by infrared was significantly improved compared with that from the traditional roasted rapeseed, with a less oily taste and pungent irritating taste, and a relatively stronger roasted aroma, as well as less polycyclic aromatic hydrocarbons in terms of type and content. Heating the cold pressed rapeseed oil prepared by pressing rapeseed without any treatment for 3 h resulted in 3.86 times and 6.28 times increase of (E,E)-2-4-hepadienal and (E,E)-2-4-decadiena, respectively. With the increase of infrared roasting temperature, the contents of glucosinolate compounds, free amino acids and reducing sugar in the defatted rapeseed treated by infrared roasting were reduced from 30.73 mg/kg, 25.61 mg/100 g and 7.61 mg/g to 1523 mg/kg, 15.82 mg/100 g and 2.29 mg/g respectively. The effect mechanism of infrared roasting on the flavor of rapeseed oil was mainly the degradation of unsaturated fatty acids into short and medium chain aldehydes and dilute alkenals, the degradation of glucosinolate compounds to form isothiocyanic acid and nitriles, and Maillard reaction to produce pyrazine and furan compounds.