AOAC 133rd Annual Meeting - Final Program

Scientific Sessions | Wednesday

3:45 PM Insights into Novel Technologies for Studying the Impact of Fibers on the Activity and Composition of the Gut Microbiota Frédéric Moens, ProDigest The gut microbiota is of key importance for human health and several diseases are correlated with an alteration of its compo- sition and functionality (i.e. dysbiosis). Consequently, there is a great interest in identifying prebiotics (e.g., dietary fibers), that could modulate the microbiota and its metabolism in order to bring about a positive health effect. Human intervention trials are the golden standard to validate functional properties of food products. Yet, most studies on gut microbiota are based on the analysis of faecal samples and the representativeness of these samples for the microbial processes occurring along the colon may be questioned. A complemen- tary option is represented by well-designed in vitro simulation technologies. The Simulator of the Human Intestinal Microbial Ecosystem (SHIME ® ) has already been shown to be a useful model for nutrition studies in terms of analysis of the colon micro- biota composition and activity. The SHIME ® is a scientifically validated platform representing the physiology and microbiology of the human gastrointestinal tract. Furthermore, recent advances in in vitro modeling also allow combining the study of bacte- ria-host interactions, such as mucosal adhesion (M-SHIME ® ) and interaction with the immune system, with the continuous model, thereby further increasing both the scientific output and commer- cial relevance. SYMPOSIUM: Utilization of Enzymes for Analytical Analyses—Breakthroughs and Important Cautions 3:00 PM – 4:30 PM Plaza F Chairs: Barry McCleary, Megazyme David Plank, WRSS Food and Nutrition Insights 3:00 PM Determination of Total Folates Utilizing a Tri-enzyme Microbiological Method and Michaelis-Menten Kinetics Lisa Povolny, WRSS Food & Nutrition Insights Determination of Total Folates (Vitamin B9) is important for nutri- tion labeling of foods. Folates play a critical role in normal cell growth, cell division, homocysteine levels, megaloblastic anemia and neural tube defects. Although a variety of HPLC-MS meth- odologies have been recently developed for analysis of food matrices which have been fortified with folic acid, these methods struggle with food matrices which contain significant amounts of other naturally occurring folate vitamers. Vitamer intercon- version and vitamer yield variability create inaccuracies in the quantifications by these chromatographic methods. For complex matrices containing significant amounts of naturally occurring

folate vitamers, the gold standard microbiological methods remain the best approach for quantification. However, these older turbidity methods are vulnerable to single point analyses of the resulting bacterial growth curves. We have utilized classic Michaelis-Menten enzyme kinetics to model bacterial growth as an enzyme catalyzed reaction which allows a more accurate and reproducible determination of total folate. This presentation will focus on how adherence to the first-order enzyme kinetic principles of substrate to bacteria ratios gives unique insights into the proper working range of the microbiological methods and eliminates the vulnerability of these methods to bacterial growth curve shifting. 3:15 PM Challenges in the Measurement of FOS in Baby Formulations Sean Austin, Nestec Ltd-Nestlé Research Center, Paulina Sawicka, Robert Gordon University, Aberdeen, Véronique Spichtig, Denis Cuany, Nestlé Research, Lausanne, Peter Sanders, Veronica Ernste-Nota4, Eurofins Carbohydrate Competence Centre, The Netherlands, Kommer Brunt, Rotating Disc BV, The Netherlands Non-digestible oligosaccharides are often added to infant formula or adult nutritional products as sources of fiber and/ or for their prebiotic activity. One of the most popular oligosac- charides used in such products are the fructooligosaccharides (FOS) of the inulin family. The most common methods for analysis of FOS use a hydrolysis step to break the oligosaccharides in to their monomeric units (fructose and glucose) and analyze the released monosaccharides. The hydrolysis of the analyte and of potentially interfering substances is performed using enzymes, since they have much greater specificity compared to acid hydrolysis, and after release, the monosaccharides are not further degraded. However, if the enzymes are used under the wrong conditions, or if the enzymes contain unexpected side activities, the analytical results may not be as expected. In this talk we’ll take a look at some of the work that was performed during the development of methods for FOS analysis, and some of the surprises that we discovered along the way. 3:30 PM Measurement of Lactose in Lactose-Free Products Ruth Ivory, David Mangan, Megazyme The industrial production of “lactose free” milk is typically achieved through the use of β -galactosidase to hydrolyze the lactose present. This process not only generates glucose and galactose at approximately 40 g/L concentration but also a range of lactose analogues that are produced through transgly- cosylation reactions during the desired lactose hydrolysis. These lactose analogues, with allolactose (1,6- β -D-galactosyl-glu- cose) notably present as the most prominent member, can often reach total concentrations of ~0.05 g/L. Given that the final concentration of lactose can in some cases be <0.01 g/L, accu- rate measurement of this analyte is particularly challenging. Traditional enzymatic lactose determination procedures involve use of β -galactosidase to hydrolyze the residual lactose with

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