Fermented coffee's fruity aromas demystified

 Specialty coffees are gaining traction in coffeehouses around the world -- and now a fermented version could bring a fruity taste to your morning cup of joe. This new kind of beverage has a raspberry-like taste and aroma, but what causes these sensations has been a mystery. Today, scientists report six compounds that contribute to the fermented coffee experience. The work could help increase production of the drink and make it more readily available for everyone to enjoy.

The researchers will present their results at the spring meeting of the American Chemical Society (ACS).

"There are now flavors that people are creating that no one would have ever associated with coffee in the past," says Chahan Yeretzian, Ph.D., the project's principal investigator. "The flavors in fermented coffee, for example, are often more akin to fruit juices."

This unusual type of beverage provides a unique flavor experience for consumers, and the growing demand for it means that fermented coffee beans can fetch a high price, potentially benefiting farmers. And the process by which the beans are prepared requires much less water than traditional methods, making it a more environmentally friendly alternative to a standard cup of coffee.

But despite this drink's growing popularity, the compounds that cause its distinctive flavor were unknown. And with fermented coffee becoming more popular in competitive events, some people have been concerned that the lack of knowledge about fermented coffee may make it difficult to distinguish between the genuine product and regular joe that has been illicitly adulterated. So, Yeretzian and colleagues from the Coffee Excellence Center at Zurich University of Applied Sciences sought to identify the compounds that are responsible for these new and exciting flavors. And because flavor and smell are intimately linked, studying the beverages' scents could help the team gain a better understanding of how fermented coffee's complex flavor is created.

To single out the compounds unique to fermented coffee's aromas, researchers took arabica beans and divided them into three groups. One was prepared using a wash process, which is likely how your average afternoon pick-me-up brew is made. Here, a gelatinous substance known as mucilage is stripped from the coffee bean, which is washed with water before being dried. The researchers prepared the second group using the pulped natural process -- another common approach -- in which the skin is removed from the bean, but the mucilage is left intact. Finally, the team fermented beans in the third group using carbonic maceration, a process often used in winemaking. This method was first introduced to the specialty coffee world in 2015, when the winning contestant in the World Barista Championship used it to prepare their entry. With this process, whole coffee fruits are fermented in stainless steel tanks and infused with carbon dioxide to lower the pH of the fermentation. Unlike the other brews, the coffee made with fermented beans was described as smelling intense, like raspberries with a hint of rose.

Next, the researchers brewed coffee using each type of bean and analyzed the samples with gas chromatography (GC) sniffing, also called GC olfactometry. First, the GC instrument separated individual components in the air above each sample. Then, as the compounds left the instrument, they went to a mass spectrometer for identification, and to someone sitting at the outlet to describe what they smelled.

"Because the chemical signature doesn't tell us how a compound smells, we have to rely on the human nose to detect the scent as each compound comes out of the chromatography instrument individually," says Yeretzian. This methodology can be tricky because there is a subjective element to it. "We're using people to detect scents, and everybody perceives flavors a little differently," says Samo Smrke, Ph.D., a research associate in the lab who is presenting the results. "But in this case, the panel was very consistent in the smells they described. So, what is traditionally considered a challenge was actually not an issue because the aromas were so clear."

There is one major advantage to GC sniffing. The human nose can sometimes detect scents from compounds that are at such a low concentration, they're unable to be picked up by mass spectrometry. In this case, although six compounds appeared to contribute to the intense fruity flavor and the raspberry scent of the fermented coffee, the team was only able to identify three of them: 2-methylpropanal, 3-methylbutanal and ethyl 3-methylbutanoate.

In the future, the researchers hope to identify the remaining compounds, as well as judge the intensity of different flavors and scents. Additionally, the researchers would like to know more about how these unique compounds form. Potential factors include farming practices, the variety of coffee beans, the microclimate of specific farms and the microbes present during fermentation. "There's still quite a lot of unknowns surrounding this process," says Smrke. A better understanding of the sources of these compounds could help the team standardize production methods, making it easier to produce fermented coffee at larger scales and allowing even more people to enjoy this distinctive flavor.

Obesity treatment could offer dramatic weight loss without surgery or nausea

 Imagine getting the benefits of gastric bypass surgery without going under the knife -- a new class of compounds could do just that. In lab animals, these potential treatments reduce weight dramatically and lower blood glucose. The injectable compounds also avoid the side effects of nausea and vomiting that are common with current weight-loss and diabetes drugs. Now, scientists report that the new treatment not only reduces eating but also boosts calorie burn.

The researchers will present their results today at the spring meeting of the American Chemical Society (ACS). 

"Obesity and diabetes were the pandemic before the COVID-19 pandemic," says Robert Doyle, Ph.D., one of the two principal investigators on the project, along with Christian Roth, M.D. "They are a massive problem, and they are projected to only get worse."

Gastric bypass and related procedures, known collectively as bariatric surgery, offer one solution, often resulting in lasting weight loss and even remission of diabetes. But these operations carry risk, aren't suitable for everyone and aren't accessible for many of the hundreds of millions of people worldwide who are obese or diabetic. As an alternative, Doyle says, they could tackle their metabolic problems with a drug that replicates the long-term benefits of surgery.

Those benefits are linked to a post-bypass-surgery change in the gut's secretion levels of certain hormones -- including glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) -- that signal fullness, curb appetite and normalize blood sugar. Current drugs that aim to replicate this effect primarily activate cellular receptors for GLP-1 in the pancreas and brain. That approach has shown great success in reducing weight and treating type 2 diabetes, drawing a lot of social media postings from celebrities in recent months. But many people can't tolerate the drugs' side effects, says Doyle. "Within a year, 80 to 90% of people who start on these drugs are no longer taking them." Doyle is at Syracuse University and SUNY Upstate Medical University, and Roth is at Seattle Children's Research Institute.

To address that drawback, various researchers have designed other treatments that interact with more than one type of gut hormone receptor. For example, Doyle's group created a peptide that activates two receptors for PYY, as well as the receptor for GLP-1. Dubbed GEP44, this compound caused obese rats to eat up to 80% less than they would typically eat. By the end of one 16-day study, they lost an average of 12% of their weight. That was more than three times the amount lost by rats treated with liraglutide, an injected drug that activates only the GLP-1 receptor and that is approved by the U.S. Food and Drug Administration for treating obesity. In contrast to liraglutide, tests with GEP44 in rats and shrews (a mammal that, unlike rats, is capable of vomiting) revealed no sign of nausea or vomiting, possibly because activating multiple receptors may cancel out the intracellular signaling pathway that drives those symptoms, Doyle says.

In its latest results, his team is now reporting that the weight loss caused by GEP44 can be traced not only to decreased eating, but also to higher energy expenditure, which can take the form of increased movement, heart rate or body temperature.

GEP44 has a half-life in the body of only about an hour, but Doyle's group has just designed a peptide with a much longer half-life. That means it could be injected only once or twice a week instead of multiple times a day. The researchers are now reporting that rats treated with this next-generation compound keep their new, slimmer physique even after treatment ends, which often isn't the case with currently approved drugs, Doyle says.

But weight loss isn't the only benefit of the peptide treatments. They also reduce blood sugar by pulling glucose into muscle tissue, where it can be used as fuel, and by converting certain cells in the pancreas into insulin-producing cells, helping replace those that are damaged by diabetes. And there's yet another benefit: Doyle and Heath Schmidt, Ph.D., of the University of Pennsylvania, recently reported that GEP44 reduces the craving for opioids such as fentanyl in rats. If that also works in humans, Doyle says, it could help addicts quit the illicit drugs or fend off a relapse.

The researchers have filed for patents on their compounds, and they plan to test their peptides in primates. They will also study how the treatments change gene expression and rewire the brain, and what that could mean for these compounds, as well as other types of medication.

"For a long time, we didn't think you could separate weight reduction from nausea and vomiting, because they're linked to the exact same part of the brain," Doyle says. But the researchers have now uncoupled those two pathways -- and that has implications for chemotherapy, which causes similar side effects. "What if we could maintain the benefit of chemotherapy drugs but tell the part of the brain that causes vomiting and nausea to knock it off? Then we could dose patients at a higher level, so they would have a better prognosis, and they would also have a better quality of life while undergoing chemotherapy," he says.

Dissecting the circadian clock in real time

 As our bodies and minds continue to adjust to the recent time change, debates continue around society about whether to make daylight saving time a permanent fixture, eliminate it or stay with the current semi-annual clock adjustment.

As those discussions continue, scientists at the University of California San Diego and their colleagues have made progress in understanding the circadian clock, the 24-hour cycle that synchronizes with light-dark exposure, and how it functions (scientists in circadian and sleep research recommend permanent standard time as the healthiest option when considering light and dark exposure).

Internal biological clocks exist throughout the tree of life, rhythmically influencing daily activities and behavior. Two years ago a multi-institutional team of researchers assembled a circadian clock in a test tube for the first time to probe the components of the clock's rhythms and interactions.

The "In Vitro Clock" helped the researchers analyze how the components of the clock interact in different times of the daily circadian cycle to control gene expression.

A new study led by UC San Diego and UC Merced researchers has expanded on this foundation with the development of a method to study how the circadian clock synchronizes with the environment in real time. As described in the journal Proceedings of the National Academy of Sciences, real-time capability allowed them to explore deeper into the clock's previously unknown internal functions, including how time-setting signals are transmitted from its core -- known as the oscillator -- to the expression of genes that ensure a properly functioning clock.

Postdoctoral Scholar Mingxu Fang and Professor Susan Golden in the School of Biological Sciences, along with their colleagues, studied an aquatic single-celled organism called a cyanobacterium, which features a circadian clock with functions similar to a human's. Their goal was to use the In Vitro Clock to examine what happens when the cyanobacterium's clock resets at the molecular level, similar to how our circadian clocks undergo time zone changes during travel. Instead of collecting samples from in vitro reactions continuously for three to four days under the previous system, their new high-throughput method allowed them to immediately track results.

One of the most important real-time findings centered on the components of the circadian clock that are responsible for relaying the circadian rhythm from the core oscillator to gene expression. The researchers found that the elements that rhythmically modify a regulator to generate circadian gene expression -- catalyzing enzymes called kinases -- also play a crucial role in how the clock functions.

"For the first two decades after its discovery, most of the research has been centered on the core oscillator," said Fang. "We now find that the kinases, previously thought to be just output components, are actually part of the whole clock."

Fang said the discovery is similar to a concept rooted in physics called the observer effect in which the act of observation also influences the observed system. In this case, in order to gain the timing information (the act of observation) kept by the core oscillator, kinases bring disturbance to the core (the observed system).

"Kinases need to ask the core oscillator what time it is by physical interaction and thus they are affecting the core in perceptible ways," said Golden, a professor and director of UC San Diego's Center for Circadian Biology. "This is part of their natural function and now we see they've become part of the machine."

In fact, two kinases are required for a properly functioning circadian clock. Researchers who study circadian biology often refer to the core oscillator as the "gears" of the clock and the two kinases as the "hands" of the clock, both of which are needed to correctly tell time.

"We now know that the hands of the clock are actually part of the time-keeping mechanism," said Golden. "If you don't have both hands they don't set time correctly because one of them is a stabilizer and one a perturber to the resetting signal, and you need both."

Prototype taps into the sensing capabilities of any smartphone to screen for prediabetes Date: March 30, 2023

 According to the U.S. Centers for Disease Control, one out of every three adults in the United States has prediabetes, a condition marked by elevated blood sugar levels that could lead to the development of Type 2 diabetes. The good news is that, if detected early, prediabetes can be reversed through lifestyle changes such as improved diet and exercise. The bad news? Eight out of 10 Americans with prediabetes don't know that they have it, putting them at increased risk of developing diabetes as well as disease complications that include heart disease, kidney failure and vision loss

Current screening methods typically involve a visit to a health care facility for laboratory testing and/or the use of a portable glucometer for at-home testing, meaning access and cost may be barriers to more widespread screening. But researchers at the University of Washington may have found the sweet spot when it comes to increasing early detection of prediabetes. The team developed GlucoScreen, a new system that leverages the capacitive touch sensing capabilities of any smartphone to measure blood glucose levels without the need for a separate reader.

The researchers describe GlucoScreen in a new paper published March 28 in the Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable and Ubiquitous Technologies.

The researchers' results suggest GlucoScreen's accuracy is comparable to that of standard glucometer testing. The team found the system to be accurate at the crucial threshold between a normal blood glucose level, at or below 99 mg/dL, and prediabetes, defined as a blood glucose level between 100 and 125 mg/dL. This approach could make glucose testing less costly and more accessible -- particularly for one-time screening of a large population.

"In conventional screening a person applies a drop of blood to a test strip, where the blood reacts chemically with the enzymes on the strip. A glucometer is used to analyze that reaction and deliver a blood glucose reading," said lead author Anandghan Waghmare, a UW doctoral student in the Paul G. Allen School of Computer Science & Engineering. "We took the same test strip and added inexpensive circuitry that communicates data generated by that reaction to any smartphone through simulated tapping on the screen. GlucoScreen then processes the data and displays the result right on the phone, alerting the person if they are at risk so they know to follow up with their physician."

Specifically, the GlucoScreen test strip samples the amplitude of the electrochemical reaction that occurs when a blood sample mixes with enzymes five times each second.

The strip then transmits the amplitude data to the phone through a series of touches at variable speeds using a technique called "pulse-width modulation." The term "pulse width" refers to the distance between peaks in the signal -- in this case, the length between taps. Each pulse width represents a value along the curve. The greater the distance between taps for a particular value, the higher the amplitude associated with the electrochemical reaction on the strip.

"You communicate with your phone by tapping the screen with your finger," Waghmare said. "That's basically what the strip is doing, only instead of a single tap to produce a single action, it's doing multiple taps at varying speeds. It's comparable to how Morse code transmits information through tapping patterns."

The advantage of this technique is that it does not require complicated electronic components. This minimizes the cost to manufacture the strip and the power required for it to operate compared to more conventional communication methods, like Bluetooth and WiFi. All data processing and computation occurs on the phone, which simplifies the strip and further reduces the cost.

The test strip also doesn't need batteries. It uses photodiodes instead to draw what little power it needs from the phone's flash.

The flash is automatically engaged by the GlucoScreen app, which walks the user through each step of the testing process. First, a user affixes each end of the test strip to the front and back of the phone as directed. Next, they prick their finger with a lancet, as they would in a conventional test, and apply a drop of blood to the biosensor attached to the test strip. After the data is transmitted from the strip to the phone, the app applies machine learning to analyze the data and calculate a blood glucose reading.

That stage of the process is similar to that performed on a commercial glucometer. What sets GlucoScreen apart, in addition to its novel touch technique, is its universality.

"Because we use the built-in capacitive touch screen that's present in every smartphone, our solution can be easily adapted for widespread use. Additionally, our approach does not require low-level access to the capacitive touch data, so you don't have to access the operating system to make GlucoScreen work," said co-author Jason Hoffman, a UW doctoral student in the Allen School. "We've designed it to be 'plug and play.' You don't need to root the phone -- in fact, you don't need to do anything with the phone, other than install the app. Whatever model you have, it will work off the shelf."

The researchers evaluated their approach using a combination of in vitro and clinical testing. Due to the COVID-19 pandemic, they had to delay the latter until 2021 when, on a trip home to India, Waghmare connected with Dr. Shailesh Pitale at Dew Medicare and Trinity Hospital. Upon learning about the UW project, Dr. Pitale agreed to facilitate a clinical study involving 75 consenting patients who were already scheduled to have blood drawn for a laboratory blood glucose test. Using that laboratory test as the ground truth, Waghmare and the team evaluated GlucoScreen's performance against that of a conventional strip and glucometer.

Given how common prediabetes and diabetes are globally, this type of technology has the potential to change clinical care, the researchers said.

"One of the barriers I see in my clinical practice is that many patients can't afford to test themselves, as glucometers and their test strips are too expensive. And, it's usually the people who most need their glucose tested who face the biggest barriers," said co-author Dr. Matthew Thompson, UW professor of both family medicine in the UW School of Medicine and global health. "Given how many of my patients use smartphones now, a system like GlucoScreen could really transform our ability to screen and monitor people with prediabetes and even diabetes."

GlucoScreen is presently a research prototype. Additional user-focused and clinical studies, along with alterations to how test strips are manufactured and packaged, would be required before the system could be made widely available, the team said.

But, the researchers added, the project demonstrates how we have only begun to tap into the potential of smartphones as a health screening tool.

"Now that we've shown we can build electrochemical assays that can work with a smartphone instead of a dedicated reader, you can imagine extending this approach to expand screening for other conditions," said senior author Shwetak Patel, the Washington Research Foundation Entrepreneurship Endowed Professor in Computer Science & Engineering and Electrical & Computer Engineering at the UW.