Ricinoleic acid

Methanol, acetonitrile, formic acid, and ammonium formate were all of HPLC grade (HiPerSolv Chromanorm) and purchased from VWR International Ltd. Analytical standards of chloramphenicol, oleic acid, ricinoleic acid, and 18:1 lysophosphatidylethanolamine (Lyso PE) were purchased from Sigma Aldrich, and water was purified using a Milli-Q system (Millipore).
High-quality pasteurized milk was produced according to Italian Ministerial Decree No. 185 (D. M. 185/91, 1991) , which establishes the general requirements for raw milk intended for the production of high-quality pasteurized milk: raw milk must have a fat content of at least 3.5% and a protein content of 32 g/L. Concerning pasteurization, a typical example of effective applied time-temperature operative conditions is 77°C for 15 s. High-quality pasteurized milk samples were collected from batches that arrived daily, after milking and pasteurization, in our laboratory (1 sample per day was collected for each of the working days). Milk samples were supplied by a single trusted dairy, located between Cremona and Parma provinces, Italy. To increase the variability of the model, the sampling period lasted 6 wk, and the sample collection for validation was executed 4 mo later, to increase the variability and the seasonality of the set and the correspondent robustness of the study.

Palm oil ester (POE) was prepared in our laboratory through enzymatic alcoholysis of palm oil with oleyl alcohol using Lipozyme RM IM as the catalyst 21) . Quercetin (purity ＞90％) and ricinoleic acid (RC) were purchased from Sigma-Aldrich (Germany) . Tween 80 (polyoxyethylene sorbitan monooleate) was purchased from Merck (Germany) . Pure soy bean lecithin was purchased from Lipoid GmbH (Ludwigshafen, Germany) . Glycerol was purchased from JT Baker (Philipsburg, NJ, USA) . Water was deionized using a Milli-Q filtration system, EMD Millipore (Billerica, MA, USA) .