Traditional Greek yoghurt is prepared following a traditional recipe, directly inside the final container, without applying any standardisation or homogenisation of milk, resulting in the formation of a thin layer at the surface of the yoghurt. This top layer, also called skin, or in Greek known as \"petsa\", is rich in fat and provides the traditional Greek yoghurt with special organoleptic characteristics that make it significantly different from any other yoghurt types [1]. As traditional Greek yoghurt's skin is not homogenous, a modified lipid extraction technique, based on liquid-liquid extraction (based on methyl tert-butyl ether) was developed in order to achieve reliable lipid extraction. After solvent evaporation, the extracts were resuspended in a generic lipidomics solvent system and analysed using RP-UHPLC-TOFMS, in both positive and negative ionisation modes, employing a generic and well-established lipidomics protocol [2]. Chemometric analysis and lipid identification were performed using MS-Dial [3] and related lipids investigation software. To the best of the authors' knowledge, a thorough lipidomic profiling of the characteristic yoghurt's skin has not yet been performed. Results indicate a highly diverse lipid profile, worthy of further investigation, especially as it is derived from non-homogenized milk. Figure 35: Automated 3D printed flow system for the transesterification of triacylglycerylycerols in edible oils. **Acknowledgments:** We acknowledge support of this work by the project \"Foodomics-GR--National Research Infrastructure for the Comprehensive Characterization of Foods\" (MIS 5029057) which is implemented under the Action \"Reinforcement of the Research and Innovation Infrastructure\", funded by the Operational Programme \"Competitiveness, Entrepreneurship and Innovation\" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund). ## References  
* (1) Serafeimidou, A.; Zlatanos, S.; Laskaridis, K.; Sagredos, A. Chemical characteristics, fatty acid composition and conjugated linoleic acid (CLA) content of traditional Greek yogurts. _Food Chem._**2012**, _134_, 1839-1846. * (2) Vorkas, P.A. ; Abellona, U.M.R. ; Li, J.V. Metabolic Profiling. In _Methods in Molecular Biology Theodoridis_; Gika, H.G., Wilson, I., Eds. ; Humana Press: New York, NY, USA, 2018; p. 1738. * (3) Tsugawa, H.; Ikeda, K.; Takahashi, M.; Satoh, A.; Mori, Y.; Uchino, H.; Okahashi, N.; Yamada, Y.; Tada, I.; Bonini, P.; et al. A lipidome atlas in MS-DIAL **4**. _Nat. Biotechnol._**2020**, _38_, 1159-1163. * (4)_17.21. The Determination of Acrylamide in Baby Foods as an Exemplary Case Study for the Role of Metrology in Food Safety_
* (5)**C. Alexopoulos 1,*, A. Georgopoulou 2, P. Giannikopoulou 1, E. Kakoulides 1, E. Skotidaki 1, E. Stathoudaki 1 and V. Schoina 1**
* (6) EXHM/GCSL-EIM, Chemical Metrology Service, General Chemical State Laboratory, 16 A. Tsocha Street, 11521 Athens, Greece
* (7) Division of Food and Alcohol, General Chemical State Laboratory, 16 A. Tsocha Street, 11521 Athens, Greece
* (8) Correspondence: metrology.gcsl@aade.gr  
Metrology institutes constitute the pinnacle of the traceability chain for measurements. Their role is to provide reference procedures and materials that are characterised by the highest accuracy coupled to the lowest possible uncertainty, providing a link to the SI. In the field of food safety, such methods and materials are of vital importance, considering the requirements for monitoring processing contaminants in food at lower concentration levels. For the past two decades, acrylamide has drawn considerable attention due to its toxicity and its presence in food undergoing heat processing [1]. Stringent performance requirements for its determination in matrices such as baby foods have been recently introduced in the European legislation [2].