Determination of Total and A1-Type β-Casein in Milk and Milk-Derived Ingredients by Liquid Chromatography-Mass Spectrometry Using Characteristic Tryptic Peptides.

Background: Gastrointestinal digestion of A1-type β-casein is conducive to β-casomorphin-7 with potential adverse digestive health effects. Monitoring of A1-type β-casein concentration in milk and milk-derived ingredients used in the formulation of A2-type nutritional products with associated health claims is important from a quality standpoint.

Objective: New analytical methods were developed and validated for total and A1-type β-casein in milk and milk-derived ingredients.

Early Enteral Administration of a Complex Lipid Emulsion Supplement Prevents Postnatal Deficits in Docosahexaenoic and Arachidonic Acids and Increases Tissue Accretion of Lipophilic Nutrients in Preterm Piglets.

Background: Preterm delivery and current nutrition strategies result in deficiencies of critical long-chain fatty acids (FAs) and lipophilic nutrients, increasing the risk of preterm morbidities. We sought to determine the efficacy of preventing postnatal deficits in FAs and lipophilic nutrients using an enteral concentrated lipid supplement in preterm piglets.

Methods: Preterm piglets were fed a baseline diet devoid of arachidonic acid (AA) and docosahexaenoic acid (DHA) and randomized to enteral supplementation as follows: (1) Intralipid (IL), (2) complex lipid supplement 1 (CLS1) with an AA:DHA ratio of 0.

Determination of Nitrite in Milk- and Soy-Based Nutritional Ingredients by Derivatization with 2,3-Diaminonaphthalene and Fluorescence Spectrometry.

Nitrite (NO2-) is an inorganic anion that can be found in various powdered milk- and soy-based nutritional ingredients as an incidental contaminant. Reliable determination of NO2- in nutritional ingredients is of paramount importance to ensure the safety of finished products. The derivatization reaction of NO2- with 2,3-diaminonaphthalene with the formation of fluorescent 2,3-naphtotriazole has been adapted to milk- and soy-based nutritional ingredients.

The development and validation of a high-throughput LC-MS/MS method for the analysis of endogenous β-hydroxy-β-methylbutyrate in human plasma.

A high-throughput, sensitive, and rugged liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the rapid quantitation of β-hydroxy-β-methylbutyrate (HMB) in human plasma has been developed and validated for routine use. The method uses 100 μL of plasma sample and employs protein precipitation with 0.1% formic acid in methanol for the extraction of HMB from plasma.

Determination of emerging nitrogenous economic adulterants in milk proteins by high-performance liquid chromatography/compact mass spectrometry.

Rationale: Milk-derived ingredients are widely used around the world in the manufacturing of nutritional products. They are prone to economically motivated adulteration with nitrogenous compounds such as melamine and its analogs in order to increase the nitrogen content of these ingredients. The need to rapidly screen milk-derived ingredients to detect adulteration is of paramount public health concern.

Analysis of Glyphosate and Aminomethylphosphonic Acid in Nutritional Ingredients and Milk by Derivatization with Fluorenylmethyloxycarbonyl Chloride and Liquid Chromatography-Mass Spectrometry.

A straightforward analytical method based on derivatization with fluorenylmethyloxycarbonyl chloride and liquid chromatography-mass spectrometry has been developed for the analysis of residues of glyphosate and aminomethylphosphonic acid (AMPA) in a suite of nutritional ingredients derived from soybean, corn, and sugar beet and also in cow's milk and human breast milk. Accuracy and intermediate precision were 91-116% and <10% RSD, respectively, in soy protein isolate. Limits of quantitation were 0.

Direct Analysis of Leucine and Its Metabolites β-Hydroxy-β-methylbutyric Acid, α-Ketoisocaproic Acid, and α-Hydroxyisocaproic Acid in Human Breast Milk by Liquid Chromatography-Mass Spectrometry.

A direct, quantitative, and confirmatory method based on stable isotope dilution liquid chromatography-mass spectrometry was developed and validated for the analysis of leucine and metabolites β-hydroxy-β-methylbutyric acid (HMB), α-ketoisocaproic acid (KIC), and α-hydroxyisocaproic acid (HICA) in human breast milk. Chromatographic resolution was achieved between isobaric leucine and isoleucine. Accuracy and intermediate precision were 89-117% and <10% relative standard deviation (RSD) across three validation runs.

Investigation of the presence of β-hydroxy-β-methylbutyric acid and α-hydroxyisocaproic acid in bovine whole milk and fermented dairy products by a validated liquid chromatography-mass spectrometry method.

A simple, rugged, quantitative, and confirmatory method based on liquid chromatography-mass spectrometry was developed and comprehensively validated for the analysis of the leucine metabolites β-hydroxy-β-methylbutyric acid (HMB) and α-hydroxyisocaproic acid (HICA) in bovine whole milk and yogurt. Mean accuracy (90-110% for HMB and 85-115% for HICA) and total precision (<10% RSD in most cases, except for <20% RSD for HMB at the limit of quantitation) at four concentration levels across three validation runs have been determined. Limits of quantitation for HMB and HICA in whole milk were 20 and 5 μg/L, respectively.

Liquid chromatography-mass spectrometry method for the quantitative determination of residues of selected veterinary hormones in powdered ingredients derived from bovine milk.

A rugged, quantitative liquid chromatography-tandem mass spectrometry method with modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation for 17 selected veterinary hormones in six different powdered ingredients derived from bovine milk was developed and comprehensively validated. A universal post-extraction spiked matrix-matching approach based on whole milk powder has been successfully implemented. Three validation runs based on four levels of pre-extraction spiked quality control (QC) samples have been conducted.

Characterization of three berry standard reference materials for nutrients.

The National Institute of Standards and Technology (NIST) has been working with the National Institutes of Health Office of Dietary Supplements to produce Standard Reference Materials (SRMs) of interest to analysts of dietary supplements. Some of these SRMs are traditional foods including SRM 3281 Cranberry (Fruit), SRM 3282 Low-Calorie Cranberry Juice Cocktail, and SRM 3287 Blueberry (Fruit), which have been characterized for nine nutritional elements and sugars. The blueberries have also been characterized for proximates, two water-soluble vitamins, and amino acids.

Analysis of organic acids in fruit juices by liquid chromatography-mass spectrometry: an enhanced tool for authenticity testing.

Organic acid analysis plays a fundamental role in the testing of authenticity of fruit juices. Analytical methods used routinely for organic acids suffer from poor reproducibility, often give false positives/negatives for tartaric acid, and do not offer the possibility of analyte confirmation. There are conflicting reports in the literature on the presence/absence of tartaric acid in pomegranate juice, a potential indicator of adulteration with grape juice.

Comparison of analytical methods to determine sodium content of low-sodium foods.

U.S. nutrition labeling regulations require the declaration of sodium content on food products.

Formation of acrylamide from lipids.

Heating amino acids with dietary oils or animal fats at elevated temperatures produced various amounts of acrylamide. The amount of acrylamide formation corresponded to the degree of unsaturation of the oils and animal fats. The decreasing order of acrylamide formation from dietary oils or animal fats with asparagine was sardine oil (642 microg/g asparagine) > cod liver oil (435.

Correlation of acrylamide generation in thermally processed model systems of asparagine and glucose with color formation, amounts of pyrazines formed, and antioxidative properties of extracts.

The relations between the formation of acrylamide and color, pyrazines, or antioxidants in an asparagine/d-glucose browning model system under various conditions were investigated. The highest level of acrylamide was produced in the asparagine/glucose (1:3) system heated at 170 degrees C for 30 min (2629 microg/g asparagine). Color intensity increased with temperature and heating time.