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Team TFS
Team TFS
sample preparation fat content determination methodLike many others, I too have been following the ongoing story on the relationship between dietary fats and increased risk of cardiovascular disease not only from a personal standpoint but also from a chemist's perspective trying to find sample preparation solutions for challenging food matrices like extracting fat from processed foods like chocolate before analysis (link to downloadable PDF on method). In previous decades, the connection between dietary fats and increased risk of cardiovascular (link to peer-reviewed study) has been extensively studied and because of these studies, limiting saturated-fat consumption has been a long-standing dietary mantra for the past 30 years. But, recent meta-analyses of nearly two dozen studies, suggests that we may have picked the wrong culprit to reduce from our diets for decades. Processed carbohydrates, which many Americans eat today in place of fat, may increase the risk of obesity, diabetes, and heart disease more than fat does—a finding that has serious implications for new U.S. dietary guidelines expected this year.

The proposed dietary recommendation jointly issued and updated every 5 years by the U.S. government will not only lower the amount of saturated fats from the current 7.9% to approximately 6% to allow for consumption of foods naturally containing solid fats (e.g. dairy, meats, poultry, eggs, or solid fats added to processed foods), but also recommend individuals to reduce consumption of refined carbohydrates and added sugar and replace them with healthy sources of carbohydrates (e.g., whole grains, legumes, vegetables, and fruits), and healthy sources of fats (e.g., non-hydrogenated vegetable oils that are high unsaturated fats, and nuts/seeds).

A statement made by David Ludwig, director of the obesity program at Children’s Hospital Boston, in a Scientific American article titled, Carbs against Cardio: More Evidence that Refined Carbohydrates, not Fats, Threaten the Heart, that I recently read caught my attention. Consider this: "If you reduce saturated fat and replace it with high glycemic-index carbohydrates, you may not only not get benefits—you might actually harm yourself,” Ludwig argues. The next time you eat a piece of buttered toast, he says, consider that “butter is actually the more healthful component.”

To increase awareness of the consumer, the U.S. FDA’s Nutrition Labeling and Education Act of 1990 (NLEA) requires that all nutrient content claims be verified and nutrient labels are required to declare the amount of fat, calories, cholesterol, carbohydrates, and dietary fiber in every serving of packaged food. This poses an analytical challenge to the food and beverage industry due to the diverse types of samples that need to be analyzed.

Fats and carbohydrates are important food components affecting taste and nutrition. The determination of the types and concentrations of fats and carbohydrates in foods is integral for energy evaluation, nutritional labeling, quality control, and for identifying possible adulteration. I would like to highlight two application notes that look at the topics of total unbound fat in various snack foods, and analysis of simple carbohydrates in beverages.

Application Update 195, Fast Determination of Total Unbound Fat in Snack Foods Using Accelerated Solvent Extraction and the ..., describes the use of a Thermo Scientific Dionex ASE 350 Accelerated Solvent Extractor system to extract fat from different snack foods. The accelerated solvent extraction (ASE) technique is now widely used for food applications in place of Soxhlet, sonication or other labor intensive and solvent extensive techniques. This application demonstrates a fast and simple gravimetric determination of total unbound fat in snack foods using the ASE technique combined with drying using the Rocket Evaporator. Several different snack foods were studied ranging from reduced fat baked crackers to cheese flavored snacks and the fats levels measured ranged from 12.2 to 35.6% fat wt/wt. The results were comparable to the reported label content showing that the accelerated solvent extraction results are accurate for total fat analysis.

Technical Note 135, Determination of Monosaccharides and Disaccharides in Beverages by capillary HPAE-PAD, describes the use of the Thermo Scientific Dionex CarboPac PA20 capillary ion chromatography column on a Thermo Scientific Dionex ICS-4000 Capillary High-Pressure Ion Chromatography (HPIC) system to separate glucose, fructose, and sucrose. This application combines the advantages of a Reagent-Free IC (RFIC) system to accurately deliver precise concentrations of eluent and a capillary format ion chromatography technique to determine sugars in diluted beverages. This study demonstrates mono- and disaccharides determinations in diluted beverage samples by High Performance Anion Exchange Pulsed Amperometric Detection (HPAE-PAD) (link to downloadable white paper) at capillary flow rates on the Dionex ICS-4000 HPIC Integrated system. The eluent was electrolytically generated inline thereby delivering the eluent precisely and accurately while minimizing carbonate contamination and eliminating errors associated with manual preparation. Monosaccharides and dissacharides ratios and concentration are often used to characterize the beverage quality, authenticity and assist in defining the plant source of the added sugar. Fruit juices have naturally occurring fructose, glucose, and sucrose in different proportions characteristic of the fruit. Cane and beet sugar are 100% sucrose but high fructose corn syrups (HFCs) are 45/55 or 58/42 glucose/fructose. In these experiments, glucose, fructose, and sucrose were separated in several different products ranging from apple cider to ready to drink teas. Some products were found to contain HFCs while other did not.

By the way, the stunning image accompanying this blog post is of fat and cholesterol cells.


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