Abstract:Here organic and non-organic Holstein raw milk and ultra-high temperature（UHT）milk from three Chinese dairy companies were collected，and gas chromatography was used to detect the composition of fatty acids（FAs）.Principal component analysis（PCA）and descriptive statistics were conducted，and soft independent modeling of class analogies（SIMCA）was established.As a result，PCA showed that raw milk and UHT milk were both clustered according to the organic and non-organic feeding patterns，indicating that FAs fingerprints between organic and non-organic milk were different.However，the clustering positions of organic and non-organic raw milk from different dairy companies were not consistent，implying that the feeding pattern and feeding standards of different dairy farms were distinct；while the clustering positions and trend of the organic and non-organic UHT milk from different dairy companies were consistent，which may be contributed to the mixture of multiple farm's raw milk in ultra big bulk tank and the standardized procedure during UHT milk production.The independent samples t-test showed that most single fatty acid had significant or extremely significant difference between organic and non-organic milk，but there was no remarkable difference in overall FAs mean in the paired t-test；in other words，traditional statistics could not distinguish the complex overall differences of FAs in organic and nonorganic milk.Generally，the content of α-linolenic acid（C18∶3n3）and linoleic acid（C18∶2n6c）in organic milk was markedly higher than that in non-organic milk，while the content of C16∶0 and C16∶1 was higher in non-or－ganic milk.The ratio of key FAs between organic and non-organic milk in the three dairy companies were different，which further suggested that feeding pattern or feed formula varied among different dairy companies.The accuracy rates of SIMCA internal and external validation for organic and non-organic UHT milk authentication were 100% and 90.5%，respectively，and FAs fingerprint modeling was feasible to distinguish between organic and non-organic UHT milk.