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Retaining flavor while removing caffeine − a chemist explains the chemistry behind decaf coffee

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theconversation.com – Michael W. Crowder, Professor of Chemistry and Biochemistry, Miami University – 2024-07-23 07:13:15

Several processes can take most of the caffeine out of coffee.
AP Photo/John Minchillo

Michael W. Crowder, Miami University

For many people, the aroma of freshly brewed coffee is the start of a great day. But caffeine can cause headaches and jitters in others. That’s why many people reach for a decaffeinated cup instead.

I’m a chemistry professor who has taught lectures on why chemicals dissolve in some liquids but not in others. The processes of decaffeination offer great real-life examples of these chemistry concepts. Even the best decaffeination method, however, does not remove all of the caffeine – about 7 milligrams of caffeine usually remain in an 8-ounce cup.

Producers decaffeinating their coffee want to remove the caffeine while retaining all – or at least most – of the other chemical aroma and flavor compounds. Decaffeination has a rich history, and now almost all coffee producers use one of three common methods.

All these methods, which are also used to make decaffeinated tea, start with green, or unroasted, coffee beans that have been premoistened. Using roasted coffee beans would result in a coffee with a very different aroma and taste because the decaffeination steps would remove some flavor and odor compounds produced during roasting.

The carbon dioxide method

In the relatively new carbon dioxide method, developed in the early 1970s, producers use high-pressure CO₂ to extract caffeine from moistened coffee beans. They pump the CO₂ into a sealed vessel containing the moistened coffee beans, and the caffeine molecules dissolve in the CO₂.

Once the caffeine-laden CO₂ is separated from the beans, producers pass the CO₂ mixture either through a container of water or over a bed of activated carbon. Activated carbon is carbon that’s been heated up to high temperatures and exposed to steam and oxygen, which creates pores in the carbon. This step filters out the caffeine, and most likely other chemical compounds, some of which affect the flavor of the coffee.

These compounds either bind in the pores of the activated carbon or they stay in the water. Producers dry the decaffeinated beans using heat. Under the heat, any remaining CO₂ evaporates. Producers can then repressurize and reuse the same CO₂.

This method removes 96% to 98% of the caffeine, and the resulting coffee has only minimal CO₂ residue.

This method, which requires expensive equipment for making and handling the CO₂, is extensively used to decaffeinate commercial-grade, or supermarket, coffees.

Swiss water process

The Swiss water method, initially used commercially in the early 1980s, uses hot water to decaffeinate coffee.

Initially, producers soak a batch of green coffee beans in hot water, which extracts both the caffeine and other chemical compounds from the beans.

It’s kind of like what happens when you brew roasted coffee beans – you place dark beans in clear water, and the chemicals that cause the coffee’s dark color leach out of the beans into the water. In a similar way, the hot water pulls the caffeine from not yet decaffeinated beans.

During the soaking, the caffeine concentration is higher in the coffee beans than in the water, so the caffeine moves into the water from the beans. Producers then take the beans out of the water and placed them into fresh water, which has no caffeine in it – so the process repeats, and more caffeine moves out of the beans and into the water. The producers repeat this process, up to 10 times, until there’s hardly any caffeine left in the beans.

The resulting water, which now contains the caffeine and any flavor compounds that dissolved out from the beans, gets passed through activated charcoal filters. These trap caffeine and other similarly sized chemical compounds, such as sugars and organic compounds called polyamines, while allowing most of the other chemical compounds to remain in the filtered water.

Producers then use the filtered water – saturated with flavor but devoid of most of the caffeine – to soak a new batch of coffee beans. This step lets the flavor compounds lost during the soaking process reenter the beans.

YouTube video
This animation shows the steps to the Swiss water process.

The Swiss water process is prized for its chemical-free approach and its ability to preserve most of the coffee’s natural flavor. This method has been shown to remove 94% to 96% of the caffeine.

Solvent-based methods

This traditional and most common approach, first done in the early 1900s, uses organic solvents, which are liquids that dissolve organic chemical compounds such as caffeine. Ethyl acetate and methylene chloride are two common solvents used to extract caffeine from green coffee beans. There are two main solvent-based methods.

In the direct method, producers soak the moist beans directly in the solvent or in a water solution containing the solvent.

The solvent extracts most of the caffeine and other chemical compounds with a similar solubility to caffeine from the coffee beans. The producers then remove the beans from the solvent after about 10 hours and dry them.

In the indirect method, producers soak the beans in hot water for a few hours and then take them out. They then treat the water with solvent to remove caffeine from the water. Methylene chloride, the most common solvent, does not dissolve in the water, so it forms a layer on top of the water. The caffeine dissolves better in methylene chloride than in water, so most of the caffeine stays up in the methylene chloride layer, which producers can separate from the water.

A diagram showing some of the ways to decaffeinate coffee.
A few chemical processes can remove the caffeine from coffee beans.
Andy Brunning/Compound Interest, CC BY-NC

As in the Swiss water method, the producers can reuse the “caffeine-free” water, which may return some of the flavor compounds removed in the first step.

These methods remove about 96% to 97% of the caffeine.

Is decaf coffee safe to drink?

One of the common solvents, ethyl acetate, comes naturally in many foods and beverages. It’s considered a safe chemical for decaffeination by the Food and Drug Administration.

The FDA and the Occupational Safety and Health Administration have deemed methylene chloride unsafe to consume at concentrations above 10 milligrams per kilogram of your body weight. However, the amount of residual methylene chloride found in roasted coffee beans is very small – about 2 to 3 milligrams per kilogram. It’s well under the FDA’s limits.

OSHA and its European counterparts have strict workplace rules to minimize methylene chloride exposure for workers involved in the decaffeination process.

After producers decaffeinate coffee beans using methylene chloride, they steam the beans and dry them. Then the coffee beans are roasted at high temperatures. During the steaming and roasting process, the beans get hot enough that residual methylene chloride evaporates. The roasting step also produces new flavor chemicals from the breakdown of chemicals into other chemical compounds. These give coffee its distinctive flavor.

Plus, most people brew their coffee at between 190 F to 212 F, which is another opportunity for methylene chloride to evaporate.

Retaining aroma and flavor

It’s chemically impossible to dissolve out only the caffeine without also dissolving out other chemical compounds in the beans, so decaffeination inevitably removes some other compounds that contribute to the aroma and flavor of your cup of coffee.

But some techniques, like the Swiss water process and the indirect solvent method, have steps that may reintroduce some of these extracted compounds. These approaches probably can’t return all the extra compounds back to the beans, but they may add some of the flavor compounds back.

Thanks to these processes, you can have that delicious cup of coffee without the caffeine – unless your waiter accidentally switches the pots.The Conversation

Michael W. Crowder, Professor of Chemistry and Biochemistry, Miami University

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Social media before bedtime wreaks havoc on our sleep − a sleep researcher explains why screens alone aren’t the main culprit

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theconversation.com – Brian N. Chin, Assistant Professor of Psychology, Trinity College – 2025-04-08 07:49:00

Social media use before bedtime can be stimulating in ways that screen time alone is not.
Adam Hester/Tetra Images via Getty Images

Brian N. Chin, Trinity College

“Avoid screens before bed” is one of the most common pieces of sleep advice. But what if the real problem isn’t screen time − it’s the way we use social media at night?

Sleep deprivation is one of the most widespread yet overlooked public health issues, especially among young adults and adolescents.

Despite needing eight to 10 hours of sleep, most adolescents fall short, while nearly two-thirds of young adults regularly get less than the recommended seven to nine hours.

Poor sleep isn’t just about feeling tired − it’s linked to worsened mental health, emotion regulation, memory, academic performance and even increased risk for chronic illness and early mortality.

At the same time, social media is nearly universal among young adults, with 84% using at least one platform daily. While research has long focused on screen time as the culprit for poor sleep, growing evidence suggests that how often people check social media − and how emotionally engaged they are − matters even more than how long they spend online.

As a social psychologist and sleep researcher, I study how social behaviors, including social media habits, affect sleep and well-being. Sleep isn’t just an individual behavior; it’s shaped by our social environments and relationships.

And one of the most common yet underestimated factors shaping modern sleep? How we engage with social media before bed.

Emotional investment in social media

Beyond simply measuring time spent on social media, researchers have started looking at how emotionally connected people feel to their social media use.

Some studies suggest that the way people emotionally engage with social media may have a greater impact on sleep quality than the total time they spend online.

In a 2024 study of 830 young adults, my colleagues and I examined how different types of social media engagement predicted sleep problems. We found that frequent social media visits and emotional investment were stronger predictors of poor sleep than total screen time. Additionally, presleep cognitive arousal and social comparison played a key role in linking social media engagement to sleep disruption, suggesting that social media’s effects on sleep extend beyond simple screen exposure.

I believe these findings suggest that cutting screen time alone may not be enough − reducing how often people check social media and how emotionally connected they feel to it may be more effective in promoting healthier sleep habits.

How social media disrupts sleep

If you’ve ever struggled to fall asleep after scrolling through social media, it’s not just the screen keeping you awake. While blue light can delay melatonin production, my team’s research and that of others suggests that the way people interact with social media may play an even bigger role in sleep disruption.

Here are some of the biggest ways social media interferes with your sleep:

  • Presleep arousal: Doomscrolling and emotionally charged content on social media keeps your brain in a state of heightened alertness, making it harder to relax and fall asleep. Whether it’s political debates, distressing news or even exciting personal updates, emotionally stimulating content can trigger increased cognitive and physiological arousal that delays sleep onset.

  • Social comparison: Viewing idealized social media posts before bed can lead to upward social comparison, increasing stress and making it harder to sleep. People tend to compare themselves to highly curated versions of others’ lives − vacations, fitness progress, career milestones − which can lead to feelings of inadequacy and anxiety that disrupt sleep.

  • Habitual checking: Social media use after lights out is a strong predictor of poor sleep, as checking notifications and scrolling before bed can quickly become an automatic habit. Studies have shown that nighttime-specific social media use, especially after lights are out, is linked to shorter sleep duration, later bedtimes and lower sleep quality. This pattern reflects bedtime procrastination, where people delay sleep despite knowing it would be better for their health and well-being.

  • Fear of missing out, or FOMO: The urge to stay connected also keeps many people scrolling long past their intended bedtime, making sleep feel secondary to staying updated. Research shows that higher FOMO levels are linked to more frequent nighttime social media use and poorer sleep quality. The anticipation of new messages, posts or updates can create a sense of social pressure to stay online and reinforce the habit of delaying sleep.

Taken together, these factors make social media more than just a passive distraction − it becomes an active barrier to restful sleep. In other words, that late-night scroll isn’t harmless − it’s quietly rewiring your sleep and well-being.

How to use social media without sleep disruption

You don’t need to quit social media, but restructuring how you engage with it at night could help. Research suggests that small behavioral changes to your bedtime routine can make a significant difference in sleep quality. I suggest trying these practical, evidence-backed strategies for improving your sleep:

  • Give your brain time to wind down: Avoid emotionally charged content 30 to 60 minutes before bed to help your mind relax and prepare for sleep.

  • Create separation between social media and sleep: Set your phone to “Do Not Disturb” or leave it outside the bedroom to avoid the temptation of late-night checking.

  • Reduce mindless scrolling: If you catch yourself endlessly refreshing, take a small, mindful pause and ask yourself: “Do I actually want to be on this app right now?”

A brief moment of awareness can help break the habit loop.The Conversation

Brian N. Chin, Assistant Professor of Psychology, Trinity College

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Providing farmworkers with health insurance is worth it for their employers − new research

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theconversation.com – John Lowrey, Assistant Professor of Supply Chain and Health Sciences, Northeastern University – 2025-04-08 07:48:00

Farmworkers at Del Bosque Farms pick and pack melons on a mobile platform in Firebaugh, Calif., in July 2021.
AP Photo/Terry Chea

John Lowrey, Northeastern University; Timothy Richards, Arizona State University, and Zachariah Rutledge, Michigan State University

Agricultural employers who provide farmworkers with health insurance earn higher profits, even after accounting for the cost of that coverage. In addition, farmworkers who get health insurance through their employers are more productive and earn more money than those who do not.

These are the key findings from our study published in the March 2025 issue of the American Journal of Agricultural Economics.

To conduct this research, we crunched over three decades of data from the Labor Department’s National Agricultural Workers Survey. We focused on California, the nation’s largest producer of fruits, nuts and other labor-intensive agricultural products in the U.S., from 1989 to 2022.

We determined that if 20% more farmworkers got health insurance coverage, they would have earned $23,063 a year in 2022, up from $22,482 if they did not. Their employers, meanwhile, would earn $7,303 in net profits per worker annually in this same scenario, versus $6,598.

Why it matters

Roughly half of California’s agricultural employers are facing labor shortages at a time when the average age of U.S. farmworkers is also rising.

Some of them, including grape producers, are responding by investing more heavily in labor-saving equipment, which helps reduce the need for seasonal manual labor. However, automated harvesting isn’t yet a viable or affordable option for labor-intensive specialty crops such as melons and strawberries.

Despite labor shortages, agricultural employers may be reluctant to increase total compensation for farmworkers. They may also be wary of providing additional benefits such as health insurance for two main reasons.

First, seasonal workers are, by definition, transient, meaning that the employer who provides coverage may not necessarily be the same one who benefits from a healthier worker. Second, it costs an employer money but doesn’t necessarily benefit them in the future if the worker moves on.

Most U.S. farmworkers are immigrants from Mexico or Central America. Roughly 42% are immigrants who are in the U.S. without legal authorization, down from 55% in the early 2000s.

As the share of farmworkers who are unauthorized immigrants has declined, the share who are U.S. citizens – including those born here – has grown and now stands at about 39%.

The low wages farmworkers earn offer little incentive for more U.S. citizens and permanent residents to take these jobs. These jobs might become more attractive if employers offered health care coverage to protect the health of the worker and their household.

Farmworkers who lack legal authorization to be in the U.S. are not eligible for private health insurance policies, and many can’t enroll in Medicaid, a government-run health insurance program that’s primarily for low-income Americans and people with disabilities. Regardless, some employers do take steps to help them gain access to health care services. As of 2025, a large share of farmworkers remain uninsured, including many citizens and immigrants with legal status.

Limited access to health care is an unfortunate reality for farmworkers, whose jobs are physically demanding and dangerous. In addition, farmworkers are paid at or near the minimum wage and are constantly searching for their next employment opportunity. This uncertainty causes high levels of stress, which can contribute to chronic health issues such as hypertension.

What still isn’t known

It is hard to estimate the effect of employer-provided health insurance on workers and employers, since labor market outcomes are a result of highly complex interactions.

For example, wages, productivity and how long someone keeps their job are highly interdependent variables determined by the interaction between what workers seek and what employers offer. And wages do not always reflect a worker’s skills and abilities, as some people are more willing to accept a job with low pay if their compensation includes good benefits such as health insurance.

The Research Brief is a short take about interesting academic work.The Conversation

John Lowrey, Assistant Professor of Supply Chain and Health Sciences, Northeastern University; Timothy Richards, Professor of Agribusiness, Arizona State University, and Zachariah Rutledge, Assistant Professor of Agricultural, Food and Resource Economics, Michigan State University

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Being alone has its benefits − a psychologist flips the script on the ‘loneliness epidemic’

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theconversation.com – Virginia Thomas, Assistant Professor of Psychology, Middlebury – 2025-04-04 07:18:00

Studies show that choosing ‘me time’ is not a recipe for loneliness but can boost your creativity and emotional well-being.
FotoDuets/iStock via Getty Images Plus

Virginia Thomas, Middlebury

Over the past few years, experts have been sounding the alarm over how much time Americans spend alone.

Statistics show that we’re choosing to be solitary for more of our waking hours than ever before, tucked away at home rather than mingling in public. Increasing numbers of us are dining alone and traveling solo, and rates of living alone have nearly doubled in the past 50 years.

These trends coincided with the surgeon general’s 2023 declaration of a loneliness epidemic, leading to recent claims that the U.S. is living in an “anti-social century.”

Loneliness and isolation are indeed social problems that warrant serious attention, especially since chronic states of loneliness are linked with poor outcomes such as depression and a shortened lifespan.

But there is another side to this story, one that deserves a closer look. For some people, the shift toward aloneness represents a desire for what researchers call “positive solitude,” a state that is associated with well-being, not loneliness.

As a psychologist, I’ve spent the past decade researching why people like to be alone – and spending a fair amount of time there myself – so I’m deeply familiar with the joys of solitude. My findings join a host of others that have documented a long list of benefits gained when we choose to spend time by ourselves, ranging from opportunities to recharge our batteries and experience personal growth to making time to connect with our emotions and our creativity.

YouTube video
Being alone can help remind people who they are.

So it makes sense to me why people live alone as soon as their financial circumstances allow, and when asked why they prefer to dine solo, people say simply, “I want more me time.”

It’s also why I’m not surprised that a 2024 national survey found that 56% of Americans considered alone time essential for their mental health. Or that Costco is now selling “solitude sheds” where for around US$2,000 you can buy yourself some peace and quiet.

It’s clear there is a desire, and a market, for solitude right now in American culture. But why does this side of the story often get lost amid the warnings about social isolation?

I suspect it has to do with a collective anxiety about being alone.

The stigma of solitude

This anxiety stems in large part from our culture’s deficit view of solitude. In this type of thinking, the desire to be alone is seen as unnatural and unhealthy, something to be pitied or feared rather than valued or encouraged.

This isn’t just my own observation. A study published in February 2025 found that U.S. news headlines are 10 times more likely to frame being alone negatively than positively. This type of bias shapes people’s beliefs, with studies showing that adults and children alike have clear judgments about when it is – and importantly when it is not – acceptable for their peers to be alone.

This makes sense given that American culture holds up extraversion as the ideal – indeed as the basis for what’s normal. The hallmarks of extraversion include being sociable and assertive, as well as expressing more positive emotions and seeking more stimulation than the opposite personality – the more reserved and risk-averse introverts. Even though not all Americans are extraverts, most of us have been conditioned to cultivate that trait, and those who do reap social and professional rewards. In this cultural milieu, preferring to be alone carries stigma.

But the desire for solitude is not pathological, and it’s not just for introverts. Nor does it automatically spell social isolation and a lonely life. In fact, the data doesn’t fully support current fears of a loneliness epidemic, something scholars and journalists have recently acknowledged.

In other words, although Americans are indeed spending more time alone than previous generations did, it’s not clear that we are actually getting lonelier. And despite our fears for the eldest members of our society, research shows that older adults are happier in solitude than the loneliness narrative would lead us to believe.

YouTube video
It’s all a balancing act – along with solitude, you need to socialize.

Social media disrupts our solitude

However, solitude’s benefits don’t automatically appear whenever we take a break from the social world. They arrive when we are truly alone – when we intentionally carve out the time and space to connect with ourselves – not when we are alone on our devices.

My research has found that solitude’s positive effects on well-being are far less likely to materialize if the majority of our alone time is spent staring at our screens, especially when we’re passively scrolling social media.

This is where I believe the collective anxiety is well placed, especially the focus on young adults who are increasingly forgoing face-to-face social interaction in favor of a virtual life – and who may face significant distress as a result.

Social media is by definition social. It’s in the name. We cannot be truly alone when we’re on it. What’s more, it’s not the type of nourishing “me time” I suspect many people are longing for.

True solitude turns attention inward. It’s a time to slow down and reflect. A time to do as we please, not to please anyone else. A time to be emotionally available to ourselves, rather than to others. When we spend our solitude in these ways, the benefits accrue: We feel rested and rejuvenated, we gain clarity and emotional balance, we feel freer and more connected to ourselves.

But if we’re addicted to being busy, it can be hard to slow down. If we’re used to looking at a screen, it can be scary to look inside. And if we don’t have the skills to validate being alone as a normal and healthy human need, then we waste our alone time feeling guilty, weird or selfish.

The importance of reframing solitude

Americans choosing to spend more time alone is indeed a challenge to the cultural script, and the stigmatization of solitude can be difficult to change. Nevertheless, a small but growing body of research indicates that it is possible, and effective, to reframe the way we think about solitude.

For example, viewing solitude as a beneficial experience rather than a lonely one has been shown to help alleviate negative feelings about being alone, even for the participants who were severely lonely. People who perceive their time alone as “full” rather than “empty” are more likely to experience their alone time as meaningful, using it for growth-oriented purposes such as self-reflection or spiritual connection.

Even something as simple as a linguistic shift – replacing “isolation” with “me time” – causes people to view their alone time more positively and likely affects how their friends and family view it as well.

It is true that if we don’t have a community of close relationships to return to after being alone, solitude can lead to social isolation. But it’s also true that too much social interaction is taxing, and such overload negatively affects the quality of our relationships. The country’s recent gravitational pull toward more alone time may partially reflect a desire for more balance in a life that is too busy, too scheduled and, yes, too social.

Just as connection with others is essential for our well-being, so is connection with ourselves.The Conversation

Virginia Thomas, Assistant Professor of Psychology, Middlebury

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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