Determination of Lactose in Lactose-Free and Low-Lactose Milk, Milk Products, and Products Containing Dairy Ingredients by the LactoSens®R Amperometry Method: Final Action 2020.01.

BACKGROUND: The LactoSens®R method was previously shown to have acceptable accuracy and repeatability precision as required by AOAC Standard Method Performance Requirements (SMPR®) 2018.009 for determination of lactose in low-lactose or lactose-free milk, milk products, and products containing dairy ingredients and was awarded Official Method of AnalysisSM (OMA) First Action status in 2020. OBJECTIVE: The method was subjected to a multilaboratory validation (MLV) study to evaluate the reproducibility precision of the method. METHODS: Fourteen validation materials were provided to 15 laboratories in seven countries as blind duplicates. The materials ranged from 0 to 173 mg/100 g lactose. Each laboratory analyzed the blind duplicates according to OMA 2020.01. The data were analyzed for repeatability and reproducibility precision. RESULTS: RSDr values varied from 2.81 to 8.76%, and RSDR values varied from 4.25 to 12.5%. When sorted by category and concentration range, these results met the repeatability and reproducibility criteria required by SMPR 2018.009. CONCLUSIONS: The data generated in the MLV support the adoption of OMA 2020.01 as Final Action status. HIGHLIGHTS: The LactoSensR method, as described by OMA 2020.01, provides an accurate and precise determination of lactose in a variety of low-lactose and lactose-free milk, milk products, and products containing dairy ingredients in minutes.

Determination of Lactose in Lactose-Free and Low-Lactose Milk, Milk Products, and Products Containing Dairy Ingredients by the LactoSens®R Amperometry Method: First Action 2020.01.

BACKGROUND: The AOAC Stakeholder Panel on Strategic Food Analytical Methods approved Standard Method Performance Requirements (SMPR®) 2018.009 for lactose in low-lactose or lactose-free milk, milk products, and products containing dairy ingredients. The LactoSens®R Method is a biosensor assay kit developed for the determination of lactose in a variety of lactose-free or low-lactose milk, dairy, and infant formula products produced with yeast-neutral lactases. OBJECTIVE: In response to a call for methods, the LactoSensR method was validated in a single laboratory study with comparison to SMPR 2018.009. METHOD: The LactoSensR method was evaluated for calibration, interference, repeatability, recovery, and robustness. In a method comparison study samples naturally containing low levels of lactose were evaluated using LactoSensR and an accredited high-performance anion-exchange chromatography with pulsed amperometric detection. RESULTS: Calibration with lactose standard solutions was shown to be linear and the method was shown to be free of interference from a variety of sugars, vitamins, alcohols, flavorings, and other compounds. Matrix studies, including 85 spiked materials, 55 products naturally containing lactose, and 13 reference materials, resulted in RSDr of 0-10.5% at 8-100 mg lactose/100 g and 0.2-5.4% at >100 mg lactose/100 g for milk and dairy products and 1.0-6.8% for infant formula, in compliance with SMPR 2018.009 with few exceptions. Recovery was 85.0-110.3% at 8-100 mg lactose/100 g and 85.6-109.7% at >100 mg lactose/100 g for milk and dairy products and 91.1-97.0% for infant formula, also meeting the performance requirements with few exceptions. The method was shown to be robust to changes in ambient temperature, sample temperature, and sample volume. CONCLUSIONS: The LactoSensR method compares favorably with the requirements of SMPR 2018.009 and should be adopted as a First Action AOAC Official MethodSM. HIGHLIGHTS: The LactoSensR method is a fast, easy-to-use method that meets the requirements of SMPR 2018.009.

Gluten in Rice Flour and Baked Rice Products by G12 Sandwich ELISA: First Action 2014.03.

The Protein and Enzymes Technical Committee of American Association of Cereal Chemists initiated a collaborative study to confirm whether the G12 antibody-based sandwich ELISA test kit is able to detect gluten in the lower mg/kg (ppm) level. Twenty laboratories investigated 24 heat-treated and non-heat-treated blind-coded samples with incurred gluten levels up to 100 mg/kg. The method has been validated for testing foods to conform to the defined Codex thresholds for gluten in gluten-free products at less than 20 mg gluten/kg. The collaborative study showed that low levels of gluten could be detected by G12 Sandwich ELISA with reproducibility RSDR of 32% and repeatability RSDr of 16%. Incurred samples showed a recovery between 62 and 135%. It is recommended that the method be accepted by AOAC as Official First Action.

Characterization of G12 sandwich ELISA, a next-generation immunoassay for gluten toxicity.

In this work, a monoclonal antibody called G12, raised against the most immunotoxic peptide to celiac disease patients, was used to develop a sandwich ELISA. Preliminary results on cross-reactivities, recoveries, and extraction methods of the new assay are presented. The assay calibration was performed using material from the Prolamin Working Group. The antibody's specificity was determined by crossreactivity studies on different grains, nuts, oils, and starches. Recovery of the assay was determined by spiking experiments on common food matrixes, as well as on problematic matrixes. Furthermore, sample extraction methods using ethanol, cocktail solution, and a proprietary buffer have been compared.