Identifying trace elements in food is important in order to monitor the toxic metal elements in our daily food consumption. How is X-ray fluorescence used for this?
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What are Trace Elements?
Trace elements or metal elements are minerals found in trace levels in biological tissues. Some are confirmed to be nutritionally important, while the remaining are deemed non-essential.
While trace elements generally operate as catalysts in metabolic enzymes, certain metallic ions, such as iron and copper, contribute to energy metabolism's oxidation-reduction processes. Iron, as a component of myoglobin and hemoglobin, is also critical for oxygen delivery.
All trace elements are poisonous if taken in significant quantities over an extended period of time. The gap between harmful and optimum intakes of critical trace elements to satisfy physiological requirements is significant for certain elements but considerably less for others.
Several Trace Elements Found in Our Daily Food
Heme iron is found in poultry, meats, and fish and is much more readily absorbed than inorganic iron or nonheme iron, which occurs naturally in both plant and animal sources. Diet composition statistics give no indication of how well the body absorbs iron from a particular food.
Zinc sources in food have shifted dramatically since the beginning of the millennium. Until the mid-1930s, individuals acquired almost similar quantities of zinc from plants and animals meals, but after 1960, over 70% of zinc in the food supply has come from animal foods. Zinc derived from animal sources seems to be more readily absorbed than zinc derived from plants.
Fluoride is an intimately connected part of the food chain. Researchers in the journal Critical Reviews in Food Science and Nutrition state that the fluoride concentration of dry cereals is highly dependent on the fluoride content in water used to prepare them. Additionally, they stated that infant diets contain significant quantities of fluoride. Fluoride is also absorbed inadvertently via two primary sources: mechanically boned beef products and fluoride toothpaste.
Copper is an important component that is found in a broad variety of foods and beverages. Copper is found in oysters and other crustaceans, whole grains, potatoes, beans, nuts, and protein sources (kidneys, liver). Copper is also found in dark leafy green vegetables, dried fruits including cocoa, prunes, black pepper, and yeast.
Chromium is a trace element that is necessary for optimal glucose metabolism. The liver as well as other protein sources, whole grains, brewer's yeast, and nuts are the best sources of chromium. Acidic meals accelerate the leach of chrome from stainless steel kitchenware. With processing, the quantity of chromium in foodstuffs tends to decrease. In general, chromium consumption is around 50% of the recommended amount.
Trace Element Harmful Effect and Ways to Detect Them
Heavy metals are very dangerous pollutants in the food chain because they are not biodegradable and have a lengthy biological life, which means they may accumulate in the human body. The growing pollution of the environment in which food is cultivated is one of the primary reasons for monitoring hazardous element levels in food.
These metals may enter the food chain through a variety of metabolic processes, where they are eventually digested, biomagnified, and endanger human health. Heavy metals are significant food pollutants, and the issue is becoming more severe on a worldwide scale as a result of lax regulation, polluted soil, and tainted fertilizer.
Sea fishing is a critical industry, however, industrial pollution of heavy metals such as lead and nickel has necessitated the examination of staple seafood such as tuna and, more specifically, shellfish for heavy metals pollution using technologies such as XRF.
XRF (X-Ray Fluorescence) Detects Trace Minerals in Food
The food sector is continually on the search for ways to enhance the quality and safety of its goods. To safeguard food trademarks against counterfeit and adulteration, the food industry must adopt sophisticated analytical procedures such as XRF analysis.
Due to the fact that XRF spectrometry is a comparison method, it needs a set of calibrators to accomplish quantitative measurements, which may be challenging in the business due to the broad variety of sample types.
As a result, a current study in the journal Applied Spectroscopy focuses on the use of XRF in conjunction with sample preparation for carbonization. The solid sample in pellet form is suited for PIXE or XRF analysis because thick targets are often easier and quicker to create than thin targets and provide lower contamination and material loss during analysis.
Advantage of Using XRF and Future Development for Detecting Trace Elements
Recently, X-ray fluorescence or XRF methods have become more popular in the fields of agriculture and food research. Its features include simple noninvasive analysis, sample preparation, multiple element measurements, and high spatial resolutions within a single sample.
Modern technology, such as sensors, scan systems, and beamline capability advancements, among others, will considerably improve the future use of X-ray fluorescence methods.
Combining XRF with additional predictive methods such as data analytics or chemometrics would significantly increase its performance. These further advancements open up fascinating new possibilities for the use of X-ray fluorescence in the fields of food and agricultural research.
References and Further Reading
Marguí, E., et al. 2014. Total reflection X-ray spectrometry (TXRF) for trace elements assessment in edible clams. Applied Spectroscopy. doi: https://journals.sagepub.com/doi/abs/10.1366/13-07364
Feng, X. 2020. X-ray fluorescence application in food, feed, and agricultural science: a critical review. Critical Reviews in Food Science and Nutrition page 1-11. https://www.researchgate.net/publication/342224179_X-ray_fluorescence_application_in_food_feed_and_agricultural_science_a_critical_review
Siddiquee, M., et al. 2014. Determination of traces of molybdenum and lead in foods by x-ray fluorescence spectrometry. SpringerPlus 3(1):341. https://springerplus.springeropen.com/articles/10.1186/2193-1801-3-341
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