采用改进QuEChERS-气相色谱- 质谱法（GC-MS）技术测定不同脂肪含量牛奶中19种酯类风味物质，研究牛奶中酯类风味物质与脂肪含量的关系。样品中的酯类风味物质经乙腈提取和PSA净化，净化后的样液经滤膜过滤后采用气相色谱-质谱法测定。19种酯类风味物质经DB-FFAP色谱柱分离，单离子监测模式测定，外标法定量。结果表明，19种酯类风味物质在5.0~500.0 μg/L质量浓度范围内具有很好的线性关系，相关系数均高于0.999。通过牛奶样品的加标回收试验，19种酯类风味物质的平均回收率在74.7%~109.2%之间，日内精密度（n=6）在1.9%~8.5%之间，方法检出限和定量限分别为3.5~14.0 μg/kg和10.0~40.0 μg/kg。实际样品检测发现牛奶中检出的δ-葵内酯、γ-十二内酯和δ-十二内酯的含量与脂肪含量正相关，且全脂纯牛奶＞低脂纯牛奶＞脱脂纯牛奶；此外，部分牛奶样品可能添加有香精香料，导致γ-壬内酯和γ-十一内酯的含量明显升高。该方法快速简便、准确度高、重现性好，可满足不同脂肪含量牛奶中19种酯类风味物质的检测要求。

A modified “quick, easy, cheap, effective, rugged and safe” (QuEChERS)-gas chromatography-mass spectrometry (GC-MS) technique was adopted to determine 19 flavor esters in milk samples having different fat contents, and the relationship between flavor esters and fat content was investigated. The flavor esters were extracted with acetonitrile from the samples and purified using prostate specific antigen (PSA). Subsequently, the extract was filtered through a filter membrane and analyzed using GC-MS. The 19 flavor esters were separated using a DB-FFAP chromatographic column. They were then detected in the single ion monitoring (SIM) mode, and their contents were quantified using the external standard calibration method. The results showed good linear relationships for 19 flavor esters within the range of 5.0~500.0 μg/L, with their correlation coefficients (R2) being higher than 0.999. The average recoveries were in the range of 76.0%~109.2%, and the intra-day precision was 1.9%~8.5% (n=6). The limits of detection (LODs) and limits of quantification (LOQs) are 3.5~14.0 μg/kg and 10.0~40.0 μg/kg, respectively. Real-time sample detection revealed the contents of δ-decalactone, γ-dodecalactone, and δ-dodecalactone to be positively correlated with the fat content, and therefore were higher in whole milk followed by low-fat milk and by skimmed milk. In addition, flavors and fragrances may be added in some milk samples, resulting in significant increases in the contents of γ-nonalactone and γ-undelactone. The proposed method is rapid, simple, and accurate, with good reproducibility and can be used to determine 19 flavor esters in milk samples of different fat contents.

广东省重点领域研发计划项目（2022B0202050003）