白鲢鱼土霉味物质的检测与脱除

The Determination and Deodorizing of Earthy Flavor of Silver Carp

采用微波铺助蒸馏(microwave assistant distillation,MD)结合固相微萃取-气相-质谱联用(SPME-GC-MS)检测白鲢鱼鱼肉中土霉味物质土味素(geosmin,GEO)和2-甲基异莰醇(2-methylisoborneol,MIB)。微波铺助蒸馏的最佳条件是微波功率350 W蒸馏8 min,MIB和GEO的加样回收率分别是53.5%、69.9%,SD在5%以内。在浓度为0.05～5μg/kg时,MIB、GEO的GC-MS峰面积与它们的浓度之间具有良好的线性关系(R2>0.98)。采用MD-SPME-GC-MS法检测了白鲢鱼肌肉中MIB和GEO的浓度,分别是1.83和1.37μg/kg。比较了水洗法、红茶末浸泡法、酸碱法和酵母发酵法脱除鲢鱼肌肉中土霉味物质的效果,碱法效果最好,大部分土霉味物质被脱除,MIB、GEO的残留量分别为0.44和0.46μg/kg。

The microwave assistant distillation （MD） combined with solid phase micro-extract and GC-MS （SPME-GC-MS） was used to determine the earthy compounds of geosmin （GEO） and 2-methylisoborneol （MIB） in silver carp muscle. The optimized conditions of MD were： distillation at 350 W for 8 min, the recovery rate of MIB and GEO were 53.5% and 69.9% respectively, and the SD was less than 5%. In the range of 0.05 - 5 μg/kg of MIB and GEO, there was good linear relationship between their GC-MS chromatogram area and their concentration （ R2 〉 0.98）. MD-SPME-GC-MS was used to detect the MIB and GEO in the silver carp muscle, the result indicated that their concentration were 1.83 and 1.37 μg/kg respectively. Compared the effect of water-washing, marinating in red tea, acid-/alkaliprocess, and fermentation with yeast on the removing of earthy-muddy odor compounds of MIB and GEO, the alkali-process was the most effective one. MIB and GEO retained in surimi was 0.44 and 0.46 p,g/kg, respectively by alkali deodorized method.