Extract from a common kitchen spice could be key to greener, more efficient fuel cells

Turmeric, a spice found in most kitchens, has an extract that could lead to safer, more efficient fuel cells.

Researchers at the Clemson Nanomaterials Institute (CNI) and their collaborators from the Sri Sathya Sai Institute of Higher Learning (SSSIHL) in India discovered a novel way to combine curcumin -- the substance in turmeric -- and gold nanoparticles to create an electrode that requires 100 times less energy to efficiently convert ethanol into electricity.

While the research team must do more testing, the discovery brings replacing hydrogen as a fuel cell feedstock one step closer.

"Of all the catalysts for alcohol oxidation in alkaline medium, the one we prepared is the best so far," said Apparao Rao, CNI's founding director and the R. A. Bowen Professor of Physics in the College of Science's.

Fuel cells generate electricity through a chemical reaction instead of combustion. They are used to power vehicles, buildings, portable electronic devices and backup power systems.

Hydrogen fuel cells are highly efficient and do not produce greenhouse gases. While hydrogen is the most common chemical element in the universe, it must be derived from substances such as natural gas and fossil fuels because it occurs naturally on Earth only in compound form with other elements in liquids, gases or solids. The necessary extraction adds to hydrogen fuel cells' cost and environmental impact.

In addition, hydrogen used in fuel cells is a compressed gas, creating challenges for storage and transportation. Ethanol, an alcohol made from corn or other agricultural-based feeds, is safer and easier to transport than hydrogen because it is a liquid.

"To make it a commercial product where we can fill our tanks with ethanol, the electrodes have to be highly efficient," said Lakshman Ventrapragada, a former student of Rao's who worked as a research assistant at the CNI and is an alumnus of SSSIHL. "At the same time, we don't want very expensive electrodes or synthetic polymeric substrates that are not eco-friendly because that defeats the whole purpose. We wanted to look at something green for the fuel cell generation process and making the fuel cell itself."

The researchers focused on the fuel cell's anode, where the ethanol or other feed source is oxidized.

Fuel cells widely use platinum as a catalyst. But platinum suffers from poisoning because of reaction intermediates such as carbon monoxide, Ventrapragada said. It is also costly.

The researchers used gold as a catalyst. Instead of using conducting polymers, metal-organic frameworks, or other complex materials to deposit the gold on the surface of the electrode, the researchers used curcumin because of its structural uniqueness. Curcumin is used to decorate the gold nanoparticles to stabilize them, forming a porous network around the nanoparticles. Researchers deposited the curcumin gold nanoparticle on the surface of the electrode at a 100 times lower electric current than in previous studies.

Without the curcumin coating, the gold nanoparticles agglomerate, cutting down on the surface area exposed to the chemical reaction, Ventrapragada said.

"Without this curcumin coating, the performance is poor," Rao said. "We need this coating to stabilize and create a porous environment around the nanoparticles, and then they do a super job with alcohol oxidation.

"There's a big push in the industry for alcohol oxidation. This discovery is an excellent enabler for that. The next step is to scale the process up and work with an industrial collaborator who can actually make the fuel cells and build stacks of fuel cells for the real application," he continued.

But the research could have broader implications than improved fuel cells. The electrode's unique properties could lend itself to future applications in sensors, supercapacitors and more, Ventrapragada said.

In collaboration with the SSSIHL research team, Rao's team is testing the electrode as a sensor that could help identify changes in the level of dopamine. Dopamine has been implicated in disorders such as Parkinson's disease and attention deficit hyperactivity disorder. When members of the research team tested urine samples obtained from healthy volunteers, they could measure dopamine to the approved clinical range with this electrode using a cost-effective method compared to standard ones used today, Rao said.

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Where does the special scent of thyme and oregano come from?

Thyme and oregano are not only popular herbs for cooking, but also valuable medicinal plants. Their essential oils contain thymol and carvacrol which impart the typical flavors and are medically important. A team from Martin Luther University Halle-Wittenberg (MLU) and Purdue University in the USA has now fully identified how the plants produce these two substances. The results could simplify the breeding process and improve the pharmaceutical value of thyme and oregano. The study appears in the journal Proceedings of the National Academy of Sciences.

Thymol, which is mainly extracted from thyme, has secretolytic, antibacterial and antispasmodic properties. The plant is therefore often used in tea for colds, cough syrups and as an herbal remedy for bronchitis. In contrast, oregano contains particularly high levels of carvacrol, which has similar properties. Its smell is often associated with pizza sauce and other Mediterranean dishes. Both substances are chemically closely related and are produced by thyme and oregano in multi-stage processes. "It's like a production line in a factory: Every step needs to be coordinated and the desired product only emerges when the steps are carried out in the right order," explains Professor Jörg Degenhardt from the Institute of Pharmacy at MLU. Instead of machines, specific biomolecules -- enzymes -- carry out this work in special glands on the surface of the leaves.

Together with researchers from Purdue University in the USA, the team in Halle decoded the individual production steps, thereby solving a decades-old mystery. "For a long time it was assumed that p-Cymene was an intermediate product of thymol and carvacrol synthesis. However, it was chemically not feasible for thymol or carvacrol to ultimately be produced from this substance," says Degenhardt. In fact, normal production of the two substances does not produce any p-Cymene at all, but rather an extremely unstable intermediate product. "This is only present for a few moments in the plant cells, which is why observing it is so difficult. However, it represents the hitherto missing step in the synthesis of the two substances," says Degenhardt. The processes start out the same for both thymol and carvacrol; only in step four do different enzymes that produce the respective substances come into play. In a fifth step, thymol and carvacrol can be further converted to thymohydroquinone and thymoquinone, which have anti-inflammatory and anti-tumour effects.

The researchers were also able to use these new findings to genetically reprogramme a species of tobacco, the model plant N. benthamiana, to produce thymol. "Even though this only happened in small quantities, it meant that we were able to fully understand the synthesis pathways and the associated enzymes," summarises Degenhardt.

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Spicy breast milk?

Breast milk is the first food that babies consume. Various studies have suggested that the "taste experience" in early childhood influences eating behavior in adults. Unlike standardized infant formula, natural milk does not taste and smell the same every day. The differences are largely due to the maternal diet.

No one-to-one transfer

However, the taste and aroma of food consumed by the mother are not transferred one-to-one to her milk. Research has already shown that odor and taste active substances from garlic or coffee partly enter the mother's milk as an odor active metabolic product, while flavors from fish oil or nursing tea were of little to no significance in this respect.

The extent to which pungent substances from chili, ginger, or pepper are found in breast milk has been even less researched than aroma and taste substances. For this reason, a scientific team led by TUM has now investigated whether these substances are transferred from food to breast milk and if so, which ones.

Piperine detectable after just one hour

Through extensive mass spectrometric analyses, the team has shown that already one hour after consumption of a standardized curry dish, piperine is detectable in breast milk for several hours. "The observed maximum concentrations of 14 to 57 micrograms per liter were about 70- to 350-fold below the taste perception threshold of an adult," says Professor Corinna Dawid, who heads the Chair of Food Chemistry and Molecular Sensory Science at TUM commissarial for Professor Thomas Hofmann.

Roman Lang, who was initially involved in the study as a scientist at TUM and later at the Leibniz Institute for Food Systems Biology (LSB) adds, "It seems rather unlikely to us that the infants consciously perceive the sharpness. Nevertheless, it is conceivable that regular, low-threshold activation of the "pungent receptor" TRPV1 could help to increase tolerance for such substances later on."

Pungents from ginger or chili as well as the secondary plant compound curcumin, which is also abundant in curry, did not enter milk, according to the research. "We were particularly surprised by the latter, since piperine is supposed to significantly increase the bioavailability of curcumin according to the results of other studies," reports Roman Lang, who heads the Biosystems Chemistry & Human Metabolism research group at the LSB.

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Adding a blend of spices to a meal may help lower inflammation

Adding an array of spices to your meal is a surefire way to make it more tasty, but new Penn State research suggests it may increase its health benefits, as well.

In a randomized, controlled feeding study, the researchers found that when participants ate a meal high in fat and carbohydrates with six grams of a spice blend added, the participants had lower inflammation markers compared to when they ate a meal with less or no spices.

"If spices are palatable to you, they might be a way to make a high-fat or high-carb meal more healthful," said Connie Rogers, associate professor of nutritional sciences. "We can't say from this study if it was one spice in particular, but this specific blend seemed to be beneficial."

The researchers used a blend of basil, bay leaf, black pepper, cinnamon, coriander, cumin, ginger, oregano, parsley, red pepper, rosemary, thyme and turmeric for the study, which was recently published in the Journal of Nutrition.

According to Rogers, previous research has linked a variety of different spices, like ginger and tumeric, with anti-inflammatory properties. Additionally, chronic inflammation has previously been associated with poor health outcomes like cancer, cardiovascular disease, and overweight and obesity, which affects approximately 72 percent of the U.S. population.

In more recent years, researchers have found that inflammation can spike after a person eats a meal high in fat or sugar. While it is not clear whether these short bursts -- called acute inflammation -- can cause chronic inflammation, Rogers said it's suspected they play a factor, especially in people with overweight or obesity.

"Ultimately the gold standard would be to get people eating more healthfully and to lose weight and exercise, but those behavioral changes are difficult and take time," Rogers said. "So in the interim, we wanted to explore whether a combination of spices that people are already familiar with and could fit in a single meal could have a positive effect."

For the study, the researchers recruited 12 men between the ages of 40 and 65, with overweight or obesity, and at least one risk factor for cardiovascular disease. Rogers said the sample was chosen because people in these demographics tend to be at a higher risk for developing poorer health outcomes.

In random order, each participant ate three versions of a meal high in saturated fat and carbohydrates on three separate days: one with no spices, one with two grams of the spice blend, and one with six grams of the spice blend. The researchers drew blood samples before and then after each meal hourly for four hours to measure inflammatory markers.

"Additionally, we cultured the white blood cells and stimulated them to get the cells to respond to an inflammatory stimulus, similar to what would happen while your body is fighting an infection," Rogers said. "We think that's important because it's representative of what would happen in the body. Cells would encounter a pathogen and produce inflammatory cytokines."

After analyzing the data, the researchers found that inflammatory cytokines were reduced following the meal containing six grams of spices compared to the meal containing two grams of spices or no spices. Rogers said six grams roughly translates to between one teaspoon to one tablespoon, depending on how the spices are dehydrated.

While the researchers can't be sure which spice or spices are contributing to the effect, or the precise mechanism in which the effect is created, Rogers said the results suggest that the spices have anti-inflammatory properties that help offset inflammation caused by the high-carb and high-fat meal.

Additionally, Rogers said that a second study using the same subjects, conducted by Penn State researchers Penny Kris-Etherton and Kristina Petersen, found that six grams of spices resulted in a smaller post-meal reduction of "flow mediated dilation" in the blood vessels -- a measure of blood vessel flexibility and marker of blood vessel health.

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