肌肽对抗坏血酸-半胱氨酸模式反应形成香味化合物的影响

以固相微萃取-气相色谱-质谱联用(SPME-GC-MS)技术对抗坏血酸与半胱氨酸(ASA-Cys)的模式反应产物进行鉴定,研究了肌肽对模式反应形成香味化合物的影响。呋喃、吡嗪、噻吩、噻唑、噻吩并噻吩及脂环硫化物在内的47个香味化合物被鉴定出来,其中,含硫化合物如脂环硫化物、噻吩、噻吩并噻吩是最主要的香味成分。肌肽加入到模式体系中,一方面使一些含硫化合物的产量显著降低,甚至消失;另一方面却促进了几个含氮化合物如甲基吡嗪,乙基吡嗪,2,6-二甲基吡嗪及其它烷基吡嗪的生成。这表明在模式反应中,肌肽抑制了Cys的热降解,同时暗示了肌肽作为氮源在热降解时很可能生成了NH3,NH3与H2S和ASA降解产物发生竞争反应形成含氮化合物如烷基吡嗪,从而导致含硫化合物的产量降低。

Effect of carnosine on aroma compounds generation from Maillard reaction of ascorbic acid and cysteine

The identification of aroma compounds,formed from the model reactions of ascorbic acid and cysteine at pH 8.00 and(140±2)℃ for 2h,was performed using a solid-phase microextraction-gas chromatography-mass spectrometry(SPME-GC-MS) technique.The effect of carnosine on aroma compounds was investigated.Forty-seven aroma compounds were identified and showed that sulfur-containing compounds such as alicyclic S compounds,thiophenes and thienothiophenes were the most abundant compounds.Other compounds identified were furans,thiazoles and pyrazines.The addition of carnosine into the reaction mixture in general caused a reduction or disappearance in content of some sulfur-containing compounds.On the other hand,it facilitated the generation of several nitrogen-containing volatiles such as methylpyrazine,ethylpyrazine,2,6-dimethylpyrazine and other alkyl pyrazines.The results suggested that carnosine inhibited the thermal degradation of Cys to some extent.Furthermore,carnosine acted as a nitrogenous source to facilitate the formation of nitrogen-containing compounds,possibly by degradation to form ammonia.