AOACSPIFANMethods-2017Awards

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210 G olay & M oulin : J ournal of AOAC I nternational V ol . 99, N o . 1, 2016

INFANT FORMULA AND ADULT NUTRITIONALS

Determination of Labeled Fatty Acids Content in Milk Products, Infant Formula, and Adult/Pediatric Nutritional Formula by Capillary Gas Chromatography: Collaborative Study, Final Action 2012.13 P ierre -A lain G olay and J ulie M oulin Nestlé Research Center, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland Collaborators: M. Alewijn; U. Braun; L.F. Choo; H. Cruijsen; P. Delmonte; J. Fontecha; S. Holroyd; G. Hostetler; F. Lacoste; C. Lehmann; L. Nagelholt; S. Phillips; T. Ritvanen; A. Rizzo; O. Shimelis; C. Srigley; D. Sullivan and P. Trossat

A collaborative study was conducted on AOAC First Action Method 2012.13 “Determination of Labeled Fatty Acids Content in Milk Products and Infant Formula by Capillary Gas Chromatography,” which is based on an initial International Organization for Standardization (ISO)–International Dairy Federation (IDF) New Work Item that has been moved forward to ISO 16958:2015 | IDF 231:2015 in November 2015. It was decided to merge the two activities after the agreement signed between ISO and AOAC in June 2012 to develop common standards and to avoid duplicate work. The collaborative study was performed after having provided highly satisfactory single-laboratory validation results [Golay, P.A., & Dong, Y. (2015) J. AOAC Int. 98, 1679–1696] that exceeded the performance criteria defined in AOAC Standard Method Performance Requirement (SMPR ® ) 2012.011 (September 29, 2012) on 12 products selected by the AOAC Stakeholder Panel on Infant Formula (SPIFAN). After a qualification period of 1 month, 18 laboratories participated in the fatty acids analysis of 12 different samples in duplicate. Six samples were selected to meet AOAC SPIFAN requirements (i.e., infant formula and adult nutritionals in powder and liquid formats), and the other Six samples were selected to meet ISO-IDF requirements (i.e., dairy products such as milk powder, liquid milk, cream, butter, infant formula with milk, and cheese). The fatty acids were analyzed directly in all samples without preliminary fat extraction, except in one Received May 29, 2015. Accepted by AK July 31, 2015. The method was approved by the AOAC Official Methods Board as Final Action. See “Standards News,” (2014) Inside Laboratory Management , November/December issue. The AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) invites method users to provide feedback on the Final Action methods. Feedback from method users will help verify that the methods are fit for purpose and are critical to gaining global recognition and acceptance of the methods. Comments can be sent directly to the corresponding author. Appendixes are available on the J. AOAC Int . website, http://aoac .publisher.ingentaconnect.com/content/aoac/jaoac Corresponding author’s e-mail: pierre-alain.golay@rdls.nestle.com DOI: 10.5740/jaoacint.15-0140

sample (cheese). Powdered samples were analyzed after dissolution (i.e., reconstitution) in water, whereas liquid samples (or extracted fat) were analyzed directly. After addition of the internal standards solution [C11:0 fatty acid methyl ester (FAME) and C13:0 triacylglycerols (TAG)] to the samples, fatty acids attached to lipids were transformed into FAMEs by direct transesterification using methanolic sodium methoxide. FAMEs were separated using highly polar capillary GLC and were identified by comparison with the retention times of pure analytical standards. Quantification of fatty acids was done relative to C11:0 FAME as internal standard and to instrument response factors (determined separately using calibration standards mixture). The performance of the method (i.e., transesterification) was monitored in all samples using the second internal standard, C13:0 TAG. RSD R values were summarized separately for labeled fatty acids in SPIFAN materials and ISO-IDF materials due to different expression of results. This method was applied to representative dairy, infant formula, and adult/pediatric nutritional products and demonstrated global acceptable reproducibility precision for all fatty acids analyzed (i.e., 46 individuals and/or groups) for these categories of products. I t is well known that fatty acids play an important role in human nutrition at all periods of life. Some fatty acids are considered more desirable than others (i.e., essential fatty acids), and some, like the saturated fatty acids (SFAs) and the industrial trans fatty acids (TFAs), need to be decreased and limited in foods due to their potential contributions to cardiovascular diseases. Fatty acids are naturally present in oils and fats used as raw materials but in different concentrations. As a consequence, they are also present in manufactured food products for which strict nutritional recommendations and/or regulation are sometimes given according to the target population. To support the labeling of fatty acids, the food industry (as well as governmental laboratories) needs reliable and horizontal methods for analyzing the whole fatty acids spectrum, including TFAs. To address this need, amethod involving direct preparation of fatty acid methyl esters (FAMEs) using a high-resolution