AOACSPIFANMethods-2017Awards

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1576  H aselberger & J acobs : J ournal of AOAC I nternational V ol . 99, N o . 6, 2016 H ase berger & Jacobs: J urnal of AOAC I nternational V ol. 99, N o . 6, 2016 1

INFANT FORMULA AND ADULT NUTRITIONALS

Determination of Fructans in Infant, Adult, and Pediatric Nutritional Formulas: Single-Laboratory Validation, First Action 2016.06 Philip Haselberger and Wesley A. Jacobs Abbott Nutrition, 3300 Stelzer Rd, Columbus, OH 43219

latter has significant ramifications for methodology capable of determining both types. Because relevant ingredients are all mixtures of varying complexity, methodology based on direct determination of all the fructan forms that are present is of limited utility, especially in complex nutritional formulations. High-temperature GC methods (2, 3) and HPAEC/PAD profiling methods (4, 5) have been reported, but the lack of suitable individual reference standards limits the usefulness of methods attempting direct quantitative determination of the entire fructan profile, as does the potential presence of a complex non-fructan carbohydrate system. In addition, the direct profiling methods are generally limited to species of DP <5–8 (for the methods noted above). In one approach, profiling of test samples is used to tentatively identify the specific fructan ingredient. Subsequent quantitative analysis is then based on determination of one or a few “marker” components using a calibration curve constructed from analysis of actual commodity samples. While this type of strategy can produce accurate results under ideal circumstances, there are significant practical limitations, one of which is the growing diversity of ingredients (and suppliers). It also fails to account for the fact that even lot-to-lot differences in ingredient fructan profile is a potential source of uncertainty as well as the possibility that the final fructan profile in a food product may differ from that in the original ingredient due to changes incurred during processing.As a result of the complexities associated with direct determination, methods generally emphasize a strategy based on determination of the monosaccharides released from fructans by enzymatic hydrolysis and subsequent calculation of fructan content using appropriate correction factors. Methods basedonpost hydrolysis analysisofmonosaccharides may rely on determination of both glucose and fructose or fructose only. Both AOAC 997.08 (6) and AOAC 999.03 (7) determine glucose and fructose. In such methods the only correction factor required is for water added during hydrolysis: C fructan = k W (C G,f + C F,f ) (1) where C fructan = fructan concentration ; C G,f = concentration of glucose from fr ct ; C F,f = concentration of fructose from fructan. k w = correction factor for water = 0.9 + 0.1 DP avg where DP avg = average DP of fructan. The presence of reducing sugars negatively impacts AOAC method 999.03 (7). Because the reducing end of the molecule of F m forms is converted to a sugar alcohol, it will not react with the PAHBAH reagent ( p -hydroxybenzoic acid hydrazide) used

Received June 16, 2016. Accepted by SG July 1, 2016. This method was approved by the AOAC Expert Review Panel for SPIFAN Nutrient Methods as First Action. The Expert Review Panel for SPIFAN Nutrient Methods invites method users to provide feedback on the First Action methods. Feedback from method users will help verify that the methods are fit-for-purpose and are critical for gaining global recognition and acceptance of the methods. Comments can be sent directly to the corresponding author or methodfeedback@aoac.org. Corresponding author’s e-mail: philip.haselberger@abbott.com DOI: 10.5740/jaoacint.16-0190 of a chain of n fructose molecules with a terminal glucose molecule). Oligofructose and materials that are a mix of intact inulin and oligofructose contain both GF n and F m type molecules (F m meaning an oligosaccharide composed of a chain of m fructose molecules only). GF n structures are non- reducing while F m structures are, and the reducing nature of the A method for fructan analysis designed to comply with AOAC Standard Method Performance Requirements (SMPR ® ) 2014.002 is described. It is closely related to existing methods for fructan analysis, including AOAC 997.08 and 999.03, as well as a method previously published by Cuany et al. This new method achieves LOQ of 0.03% fructan on a ready-to-feed (RTF) basis with mean recoveries ranging from 93 to 108% in the presence of up to 9% sucrose (even at the 0.03% level of fructan). Repeatability ranged from 1.09 to 3.67%. Intermediate precision ranged from 2.46 to 6.79%. Sample preparation for quantitative analysis is simplified compared to some of the existing methodologies. The method incorporates a qualitative profile analysis to determine fructan size category. This allows assignment of appropriate correction factors without independent knowledge of fructan type. A s defined in AOAC SMPR 2014.002 (1), fructan is a general term that encompasses fructooligosaccharides, oligofructose, and inulin. These are all referred to as inulin-type fructans, despite the fact that ingredient sources relevant to this category may not necessarily be derived from inulin. These carbohydrates act as dietary fiber with prebiotic benefits and range in size from a degree of polymerization (DP) of 2 to 100. Fructans of this type are represented by two general structural forms (Figure 1). Fructooligosaccharides and intact inulin materials are comprised almost exclusively of GF n type molecules (i.e., an oligosaccharide composed