Food Quality and Sensory Department , Teagasc Food Research Centre , Moorepark, Fermoy , County Cork P61 C996 , Ireland.
Physical Sciences Department , Cork Institute of Technology , Bishopstown, Cork T12 P928 , Ireland.
J Agric Food Chem. 2019 Jan 9;67(1):499-506. doi: 10.1021/acs.jafc.8b05462. Epub 2018 Dec 21.
Accurate quantification of free fatty acids in dairy products is important for both product quality control and legislative purposes. In this study, a novel fatty acid butyl ester method was developed, where extracted free fatty acids are converted to butyl esters prior to gas chromatography with flame ionization detection. The method was comprehensively validated to establish linearity (20-700 mg/L; R > 0.9964), limits of detection (5-8 mg/L), limits of quantification (15-20 mg/L), accuracy (1.6-5.4% relative error), interday precision (4.4-5.3% relative standard deviation), and intraday precision (0.9-5.6% relative standard deviation) for each individual free fatty acid. A total of 17 dairy samples were analyzed, covering diverse sample matrices, fat content, and degrees of lipolysis. The method was compared to direct on-column injection and fatty acid methyl ester methods and overcomes limitations associated with these methods, such as either column-phase absorption or deterioration, accurate quantification of short-chain free fatty acids, and underestimation of polyunsaturated free fatty acid.
准确量化乳制品中的游离脂肪酸对于产品质量控制和立法目的都非常重要。在本研究中，开发了一种新的脂肪酸丁酯方法，其中提取的游离脂肪酸在气相色谱-火焰离子化检测前被转化为丁酯。该方法经过全面验证，以建立线性关系（20-700mg/L；R>0.9964）、检测限（5-8mg/L）、定量限（15-20mg/L）、准确度（1.6-5.4%相对误差）、日间精密度（4.4-5.3%相对标准偏差）和日内精密度（0.9-5.6%相对标准偏差）。共分析了 17 种乳制品样品，涵盖了不同的样品基质、脂肪含量和脂肪分解程度。该方法与直接柱上进样和脂肪酸甲酯方法进行了比较，并克服了这些方法存在的局限性，例如柱相吸收或降解、短链游离脂肪酸的准确定量以及多不饱和游离脂肪酸的低估。
