Tag Archives: #cooking

Pollution From Cooking Remains in Atmosphere For Longer (Food)

Particulate emissions from cooking stay in the atmosphere for longer than previously thought, making a prolonged contribution to poor air quality and human health, according to a new study.

credit: James Sutton/Unsplash

Researchers at the University of Birmingham succeeded in demonstrating how cooking emissions – which account for up to 10 per cent of particulate pollution in the UK – are able to survive in the atmosphere over several days, rather than being broken up and dispersed.

The team collaborated with experts at the University of Bath, the Central Laser Facility and Diamond Light Source to show how these fatty acid molecules react with molecules found naturally in the earth’s atmosphere. During the reaction process, a coating, or crust is formed around the outside of the particle that protects the fatty acid inside from gases such as ozone which would otherwise break up the particles.

This is the first time scientists have been able to recreate the process in a way that enables it to be studied in laboratory conditions by using the powerful X-ray beam at Diamond Light Source to follow the degradation of thin layers of molecules representative of these cooking emissions in minute detail. The results are published in the Royal Society of Chemistry’s Faraday Discussions.

The ability of these particles to remain in the atmosphere has a number of implications for climate change and human health. Because the molecules are interacting so closely with water, this affects the ability of water droplets to form clouds. In turn this may alter the amount of rainfall, and also the amount of sunlight that is either reflected by cloud cover or absorbed by the earth – all of which could contribute to temperature changes.

In addition, as the cooking emission particles form their protective layer they can also incorporate other pollutant particles, including those known to be harmful to health such as carcinogens from diesel engine emissions. These particles can then be transported over much wider areas.

Lead author, Dr Christian Pfrang, of the University of Birmingham’s School of Geography, Earth and Environmental Sciences, said: “These emissions, which come particularly from cooking processes such as deep fat frying, make up a significant proportion of air pollution in cities, in particular of small particles that can be inhaled known as PM2.5 particles. In London it accounts for around 10 per cent of those particles, but in some of the world’s megacities for example in China it can be as much as 22 per cent with recent measurements in Hong Kong indicating a proportion of up to 39%.

“The implications of this should be taken into account in city planning, but we should also look at ways we can better regulate the ways air is filtered – particularly in fast food industries where regulations do not currently cover air quality impacts from cooking extractor emissions for example.”

The research was supported by the Science and Technology Facilities Council (STFC) and the Natural Environment Research Council (NERC).

Reference: Adam Milsom, Adam M. Squires, Ben Woden, Nicholas J. Terrill, Andrew D. Ward and Christian Pfrang (2020). ‘The persistence of a proxy for cooking emissions in megacities: a kinetic study of the ozonolysis of self-assembled films by simultaneous Small & Wide Angle X-ray Scattering (SAXS/WAXS) and Raman microscopy.’ Faraday Discussions. https://pubs.rsc.org/en/Content/ArticleLanding/2020/FD/D0FD00088D#!divAbstract

Provided by University of Birmingham

Fatty Residues On Ancient Pottery Reveal Meat-heavy Diets of Indus Civilization (Archeology)

New lipid residue analyses have revealed a dominance of animal products, such as the meat of animals like pigs, cattle, buffalo, sheep and goat as well as dairy products, used in ancient ceramic vessels from rural and urban settlements of the Indus Civilisation in north-west India, the present-day states of Haryana and Uttar Pradesh.

Lead author Akshyeta Suryanarayan sampling pottery for residue analysis in the field. ©Akshyeta Suryanarayan

The study, published in Journal of Archaeological Science, was led by Dr Akshyeta Suryanarayan, former PhD student at the Department of Archaeology, University of Cambridge and current postdoctoral researcher at CEPAM, UMR7264-CNRS, France.

Dr Suryanarayan said: “The study of lipid residues involves the extraction and identification of fats and oils that have been absorbed into ancient ceramic vessels during their use in the past. Lipids are relatively less prone to degradation and have been discovered in pottery from archaeological contexts around the world. However, they have seen very limited investigation in ancient ceramics from South Asia.”

“This study is the first to investigate absorbed lipid residues in pottery from multiple Indus sites, including the Indus city of Rakhigarhi, as well as other Indus settlements of Farmana and Masudpur I and VII, allowing comparisons to be made across settlements and across time.”

The identification of specific compounds in the lipid extracts enables the detection of different plant or animal products, such as fatty acids, previously used in the vessels. Additionally, isotopic analysis of fatty acids enables the differentiation of different types of animal meat and milk. These analyses enable an understanding of vessel use and what was being cooked in them.

Suryanarayan said: “Our study of lipid residues in Indus pottery shows a dominance of animal products in vessels, such as the meat of non-ruminant animals like pigs, ruminant animals like cattle or buffalo and sheep or goat, as well as dairy products. However, as one of the first studies in the region there are interpretative challenges. Some of the results were quite unexpected, for example, we found a predominance of non-ruminant animal fats, even though the remains of animals like pigs are not found in large quantities in the Indus settlements. It is possible that plant products or mixtures of plant and animal products were also used in vessels, creating ambiguous results.”

“Additionally, despite the high percentages of the remains of domestic ruminant animals found at these sites, there is very limited direct evidence of the use of dairy products in vessels, including in perforated vessels that have been previously suggested to be linked to dairy processing. A recent Scientific Reports study has reported more evidence of dairy products, primarily in bowls in Gujarat. Our results suggest that there may have been regional differences. The analysis of more vessels from different sites would help us explore these potential patterns.”

Senior author Dr Cameron Petrie, University of Cambridge, said: “The products used in vessels across rural and urban Indus sites in northwest India are similar during the Mature Harappan period (c.2600/2500-1900 BC). This suggests that even though urban and rural settlements were distinctive and people living in them used different types of material culture and pottery, they may have shared cooking practices and ways of preparing foodstuffs.”

Complete vessel found during excavation at the Indus site of Lohari Ragho I, Haryana. ©Cameron Petrie

“There is also evidence that rural settlements in northwest India exhibited a continuity in the ways they cooked or prepared foodstuff from the urban (Mature Harappan) to post-urban (Late Harappan) periods, particularly during a phase of climatic instability after 4.2 ka BP (c.2100 BC), which suggests that daily practices continued at small rural sites over cultural and climatic changes,” Petrie said.

This study adds to existing research in the region which suggests the resilience of rural settlements in northwest India during the transformation of the Indus Civilisation, and during a period of increasing aridity.

The results also have major implications for broadening our understanding of the foodways of South Asia, as well as the relationship between pottery and foodstuffs.

Dr Suryanarayan concluded: “Our understanding of the culinary history of South Asia is still very limited but these results demonstrate that the use of lipid residues, combined with other techniques in bioarchaeology, have the potential to open exciting new avenues for understanding the relationship between the environment, foodstuffs, material culture, and ancient society in protohistoric South Asia.”

Reference: Akshyeta Suryanarayan et al, Lipid residues in pottery from the Indus Civilisation in northwest India, Journal of Archaeological Science (2020). DOI: 10.1016/j.jas.2020.105291 http://dx.doi.org/10.1016/j.jas.2020.105291

Provided by University of Cambridge

Researchers Devise New Method To Get The Lead Out (Engineering)

Commercially sold water filters do a good job of making sure any lead from residential water pipes does not make its way into water used for drinking or cooking.

Researchers in the lab of Daniel Giammar, the Walter E. Browne Professor of Environmental Engineering in the McKelvey School of Engineering, have devised a new method that allows them to extract lead from “point-of-use” filters, providing a clearer picture of what’s coming out of the faucet. ©Washington University in St. Louis.

Filters do not do a good job, however, of letting the user know how much lead was captured.

Until now, when a researcher, public works department or an individual wanted to know how much lead was in tap water, there wasn’t a great way to find out. Usually, a scientist would look at a one-liter sample taken from a faucet.

Researchers in the McKelvey School of Engineering at Washington University in St. Louis have devised a new method that allows them to extract the lead from these “point-of-use” filters, providing a clearer picture of what’s coming out of the faucet.

And they can do it in less than an hour.

Their research was published this past summer in the journal Environmental Science: Water Research & Technology.

The problem with just collecting a one-liter sample is that “We don’t know how long it was in contact with that lead pipe or if it just flowed through quickly. Everyone’s water use patterns are different,” said Daniel Giammar, the Walter E. Browne Professor of Environmental Engineering in the Department of Energy, Environmental & Chemical Engineering.

“Collecting a single liter is not a good way of assessing how much lead a resident would be exposed to if not using a filter,” he said. “To do that, you’d need to see all that the person was drinking or using for cooking.”

A better method would be to collect the lead from a filter that had been in use long enough to provide an accurate picture of household water use. Most of the commercial filters for sale at any major retail store will last for about 100 gallons — 40 times the amount of the typical water sample.

The idea to use filters in this way isn’t new, but it hasn’t been done very efficiently, precisely because the filters do such a good job at holding onto the lead.

Giammar said he had probably heard about this method previously, but a light went off after a conversation about indoor air quality. He had been talking to a professor at another institution who was monitoring indoor air quality using a box that sucked in air, collecting contaminants in a tube. The user can then remove the collection tube and send it to a lab to be analyzed.

“I said, ‘Let’s do what you’re doing with air,'” pull water through a filter, collect contaminants and then analyze them. “Then we realized, they already make and sell these filters.”

Liberating the lead

Point-of-use filters are typically made of a block of activated carbon that appears solid, almost like a lump of coal. The water filters through tiny pores in the carbon; the carbon binds to the lead, trapping it before the water flows out of the faucet.

“If you want to take the lead out of the water, you need something that is really good at strongly holding on to it,” which carbon is, Giammar said.

“So we had to hit it with something even stronger to pull that lead off.”

The solution? Acid.

Working with senior Elizabeth Johnson, graduate student Weiyi Pan tried different methods, but ultimately discovered that slowly passing an acidic solution through the filter would liberate 100% of the lead.

The entire process took about two liters of acid and about a half hour.

In the near future, Giammar sees the filters being put to use for research, as opposed to being put in the trash.

“The customer has a filter because they want to remove lead from the water. The water utility or researcher wants to know how much lead is in the home’s water over some average period of time,” Giammar said. Even if the customer doesn’t care, they’ve got this piece of data that usually they’d just throw away.

“We’d rather them send it to their utility service, or to us, and we can use it to get information.”

References: http://dx.doi.org/10.1039/d0ew00496k

Provided by Washington University in St. louis

The Maillard Reaction Is What Gives Grilled Meat Its Flavor (Food)

There’s a reason why bacon doesn’t taste as good microwaved as it does fried, and why chicken doesn’t taste as good boiled as it does roasted. That reason is the Maillard reaction, a phenomenon that takes place when denatured proteins and sugars meet temperatures of around 300-500 degrees Fahrenheit (150-260 degrees Celsius) and combine, making meat turn brown and taste absolutely delicious.

The reaction was named for its discoverer, French chemist Louis-Camille Maillard, who first wrote about its browning effects in 1912. His discovery didn’t gain immediate ground in kitchens, however. It wasn’t until the 1940s that people understood the connection between browning and flavor, and even then, most research was performed on how to avoid the reaction because the flavor changes were considered undesirable.

Eventually, scientists were able to analyze the many thousands of aromatic and flavor compounds the Maillard reaction can produce, not only in grilled meat but in bread, coffee beans, and other foods that get more flavorful as they turn brown. These compounds include pyrazines, which lend a roasted flavor; alkylpyrazines, which impart a nutty quality; and acylpyridines, which have a cracker-like aroma. So at your next barbecue, maybe give a grill-tong salute to chef Maillard for the delicious flavors you’re about to enjoy.

This Is The Healthiest Way To Prepare Broccoli, According To Science (Food)

Ask any unhappy little kid at the dinner table and they’ll tell you: Ya gotta eat your veggies. But you can do even better — scientists found a new way to prepare one common vegetable to boost its benefits to the max. Bring it on, broccoli.

Broccoli has long been a poster child for healthy foods. And that’s no coincidence: Broccoli has been found to slash blood sugar in type II diabetics, fight cancer, and more. The bad news is that not a lot of the stuff that makes broccoli so good for us survives our usual methods of preparing it. The good stuff here being sulforaphane, an antioxidant that helps prevent cancer.

Sulforaphane turns out to be pretty tricky to get at in raw broccoli. It, and compounds like it, exists in the form of glucosinolates, which need an enzyme called myrosinase to break them down. How do you get myrosinase working? Just by doing damage to the broccoli. Unfortunately, preparation methods like boiling and microwaving don’t count. They seriously reduce the levels of glucosinolates in broccoli, thus giving us less sulforaphane. Bummer.

For a study published in January 2018, Chinese researchers dove into ways of cooking broccoli that could possibly maintain its cancer-fighting goodness. They started by examining a common method in China: stir-frying. “Surprisingly, few methods have reported the sulforaphane concentrations in stir-fried broccoli, and to the best of our knowledge, no report has focused on sulforaphane stability in the stir-frying process,” the researchers noted in the study. Luckily, they figured out a method for preparing broccoli that maintains as much of the good stuff as possible.

By trying several methods and measuring the resulting sulforaphane levels, they found a healthier alternative to stir-frying. Ready? The researchers chopped up the broccoli into tiny pieces, let it sit for 90 minutes, then lightly stir-fried it. The broccoli that was left out to let the enzymes do their thing had 2.8 times as much sulforaphane content as the broccoli that was stir-fried right away. Though it increases your meal prep time, it also increases your broccoli’s nutritional power. Is it worth the extra effort? That’s up to you.

Did Our Ancestors Boil Their Food In Hot Springs? (Archeology)

A team led by researchers at MIT and the University of Alcalá in Spain has discovered evidence that hot springs may have existed in Olduvai Gorge around that time, near early human archaeological sites. The proximity of these hydrothermal features raises the possibility that early humans could have used hot springs as a cooking resource, for instance to boil fresh kills, long before humans are thought to have used fire as a controlled source for cooking.

The proximity of hot springs to early settlements have led researchers to wonder if early humans used hot springs as a cooking resource long before fire. Credit: Tom Björklund

In 2016, one of the author, named sistiaga joined an archaeological expedition to Olduvai Gorge, where researchers with the Olduvai Paleoanthropology and Paleoecology Project were collecting sediments from a 3-kilometer-long layer of exposed rock that was deposited around 1.7 million years ago. This geologic layer was striking because its sandy composition was markedly different from the dark clay layer just below, which was deposited 1.8 million years ago.

Ainara Sistiaga taking samples at Olduvai Gorge, a rift valley setting in northern Tanzania where anthropologists have discovered fossils of hominids that existed 1.8 million years ago. Credit: Ainara Sistiaga

It’s thought that around 1.7 million years ago, East Africa underwent a gradual aridification, moving from a wetter, tree-populated climate to dryer, grassier terrain. Sistiaga brought back sandy rocks collected from the Olduvai Gorge layer and began to analyze them in Summons lab for signs of certain lipids that can contain residue of leaf waxes, offering clues to the kind of vegetation present at the time.

Within the sediments she brought back, Sistiaga came across lipids that looked completely different from the plant-derived lipids she knew. She took the data to Summons, who realized that they were a close match with lipids produced not by plants, but by specific groups of bacteria that he and his colleagues had reported on, in a completely different context, nearly 20 years ago.

The lipids that Sistiaga extracted from sediments deposited 1.7 million years ago in Tanzania were the same lipids that are produced by a modern bacteria that Summons and his colleagues previously studied in the United States, in the hot springs of Yellowstone National Park.

One specific bacterium, Thermocrinis ruber, is a hyperthermophilic organism that will only thrive in very hot waters (around 80°C), such as those found in the outflow channels of boiling hot springs.

That is, it appears that heat-loving bacteria similar to those Summons had worked on more than 20 years ago in Yellowstone may also have lived in Olduvai Gorge 1.7 million years ago. By extension, the team proposes, high-temperature features such as hot springs and hydrothermal waters could also have been present.

The region where the team collected the sediments is adjacent to sites of early human habitation featuring stone tools, along with animal bones. It is possible, then, that nearby hot springs may have enabled hominins to cook food such as meat and certain tough tubers and roots.

Exactly how early humans may have cooked with hot springs is still an open question. They could have butchered animals and dipped the meat in hot springs to make them more palatable. In a similar way, they could have boiled roots and tubers, much like cooking raw potatoes, to make them more easily digestible. Animals could have also met their demise while falling into the hydrothermal waters, where early humans could have fished them out as a precooked meal.

While there is currently no sure-fire way to establish whether early humans indeed used hot springs to cook, the team plans to look for similar lipids, and signs of hydrothermal reservoirs, in other layers and locations throughout Olduvai Gorge, as well as near other sites in the world where human settlements have been found.

References: Ainara Sistiaga, Fatima Husain, David Uribelarrea, David M. Martín-Perea, Troy Ferland, Katherine H. Freeman, Fernando Diez-Martín, Enrique Baquedano, Audax Mabulla, Manuel Domínguez-Rodrigo, and Roger E. Summons, “Microbial biomarkers reveal a hydrothermally active landscape at Olduvai Gorge at the dawn of the Acheulean, 1.7 Ma”, PNAS, 2020 doi: https://doi.org/10.1073/pnas.2004532117 link: https://www.pnas.org/content/early/2020/09/14/2004532117