This is an old debate that people can't set straight. Anecdotal evidence says that dark roasts coffee give you more caffeine in the cup. Is this true though? Chemistry says that the amount of caffeine is constant, regardless of the roast levels. If anything, caffeine will likely burn at higher roasting temperatures. At the same time people notice a considerable difference between the jitters you get from a light and a dark roast.
It turns out they are both right and wrong. Dark roasts will make a more caffeinated beverage, but not because they contain more caffeine. Read on to find out.
Does Dark Roast Coffee Really Have More Caffeine?
When it comes to coffee, there’s something everyone’s talking about and nobody is talking about: caffeine. For people who drink and enjoy coffee, caffeine is on the mind and a wonderful tasting cup is a big bonus. For the folks who work in the coffee industry, we tend to want to think we’re in the deliciousness business and a part of a beautiful value chain, not that we’re administering legal drugs in liquid form. Of course, great coffee can be both things, but as is so often true about the common and ubiquitous, very little is known about the science of caffeine consumption, and there are many misconceptions around it.
Juliet Han has been pulling double-duty as the head roaster at Blue Bottle while also continuing her studies at Peralta Colleges in Oakland with a focus on science, and naturally she researches coffee whenever she can. In her just-published research paper Correlation Between Caffeine and Roast Levels Using HPLC she took on the question, “Does dark roast have more caffeine than light roast?” This is one of the most common misconceptions around coffee, and while it is something that’s been studied in the past, Han’s 15 years of varied industry experience give her a practical lens to see the question through.
Han started by considering the question and pulling it apart: Does dark roast have more caffeine than light roast? As with most questions about coffee, it depends. Even if you assume the brewing is performed consistently, when you say “more caffeine,” you’re talking about more… in what? In the cup? In the beans? In the grounds? How are you measuring the coffee? Each answer yields a different approach to the question, different scientific variables, and ultimately, different conclusions.
In her research lab, among the various tools and instruments, Han had access to an HPLC (high pressure liquid chromatography) machine, which is a common scientific tool that takes a sample and analyses it for what components are in there and in what quantities. The details of her methodology and data are in the research paper, but let’s summarize what she learned and why it matters, categorized by how we might frame the caffeine/roast question.
By the bean
One way to think about this question is: Do caffeine levels change inside the beans during roasting? On this, the science is clear: caffeine is very stable through the roasting process. You’d have to roast it past turning it into charcoal before caffeine would chemically change, beyond even the darkest of dark roasts you could find. Point is, even though the individual beans go through physical and chemical changes while it’s roasted, the amount of caffeine a bean starts with is generally the amount it ends up with. If you’re talking about individual beans, the caffeine level is the same whether it is light or dark roasted.
Of course, while this may be interesting as a bit of trivia, it’s not that relevant to our day to day coffee lives, unless you’re a coffeebeanophage, which means “person who eats whole bean coffee” and is also a word I just made up.
By the cup and weighing the grounds
Han wanted to take the variables of brewing out of the picture, so she brewed the coffee by “decoction,” which means brewing coffee by actually boiling the coffee in water. She brewed the living hell outta the coffee, extracting pretty much all the coffee that’s soluble. Boiling it for 15 minutes (as she did) is a lot, and the coffee surely tasted gross and bitter.
Coffee nerds like to weigh the coffee grounds we brew. Mass is a constant, and scoops or tablespoons give you a variable that’s imprecise and inaccurate. (Sorry, scoop lovers.) Different coffees can have very different physical characteristics, so it’s a bit misguided to think that there’s a magic brewing recipe that works all the time.
What Juliet found was that when she weighed the coffee grounds and based her calculations on that, the darker roast did in fact yield more caffeine than the lighter roast.
By the cup and by the scoop
But what if you just can’t put down that spoon or scoop? Not everyone has or wants a scale, and however imprecise scoops and spoons may be, it’s still the most common way most home coffee brewers measure their grounds. Measuring this way introduces the density of the coffee grounds into the calculations, and Han also did the calculations to see what the results were if someone used tablespoons or scoops.
I’ve gotta tell you, I love Han’s research paper. There’s a lot to love about it, but what I love most is that it inspires so many more questions and possibilities for future research.
According to this research, dark roast does in fact yield more caffeine than light roast. This is consistently what Han found across experiments, and it makes sense, though not for the reasons one might think. A darker roasted coffee is less dense, so by the bean, it has lower mass than a light roasted coffee. All other things being equal, if you grind and weigh out a certain number of grams of coffee, there are more beans involved when using dark roast. It’s no different than if we ate a pound of fresh grapes versus a pound of dried raisins—far more sugar is consumed in the dried, condensed raisin equation.
So it’s not necessarily that “dark roast has more caffeine”—caffeine is stable across roasts—but rather, dark roast is less dense. Since the caffeine is so stable, the difference mostly boils down to density.
What I think it’s interesting to note is that when you look at Han’s data, the caffeine difference between the lightest and darkest coffees was around 9% when you measured by the scoop, but about 32% when she measured by weight. That’s a big margin! While it’s the density difference between the dark and light roast coffee that gives us the difference in caffeine content, the fact that a scoop of dark roast has less mass than a scoop of light roast actually reduces the net caffeine difference in the scoops-and-spoons scenario. So while darker roast does have more caffeine, that difference is more pronounced when you measure by weight than if you’re scooping.
32% is a fairly meaningful difference. It means that 16 ounces of Han’s light roast brew would have about as much caffeine as 12 ounces of the dark roast. But when you’re thinking about how this applies to your coffee consumption, keep in mind that Juliet Han is a scientist professionally controlling her variables. Once you leave the lab and get out into the world of coffee shops and home coffeemakers (not to mention different coffees and roasters and brewing waters and brewing variables), you’re faced with the unfathomable number of factors that affect caffeine content beyond just roast level.
All in all, it appears that dark roasted coffee has more caffeine, but not for the reasons you think. That is a great bit of trivia to pull out the next time somebody brings this up at a party. “You know, dark roasted coffee has more caffeine, but not for the reasons you think!”
I can’t wait to see what other research Han and other coffee-knowledgeable scientists come up with next. Go science!
Finally, someone did some solid research on cold brew coffee.
Until this research, the "bloggers' wisdom" was that cold brew coffee has less acidity and because of that was gentle on sensitive stomachs. The work of Fuller and Rao busted this myth by showing that the ph is the same in cold and hot brew.
Anecdotally, cold brew indeed is gentler on the stomach, but that doesn't have to do with the acidity of coffee. Coffee is not acidic enough to cause pain. The pain is caused by other compounds in coffee, among which is caffeine, as pointed out by one of the cited blogs. (read critiqued blogs)
The research also showed that the total titratable acids content was higher in hot brew, which is why cold brew tastes milder.
One of the interesting things that surprised me was the antioxidant properties of the two. Previous research showed that the amount of Chlorogenic Acid decreases as the brewing temperature increases. Fuller and Rao's work uncovered other antioxidants in hot brewed coffee. Their findings showed that, in fact, hot brewed coffee contains more antioxidant than cold brew.
My point is, I read the article and I couldn't make draw a definitive conclusion. Which one is better for my health?
To be honest, I'll probably stick to my espresso...
Cold brew coffee vs. hot brew: does brewing temperature influence health benefits?
Cold brew coffee has recently become a go-to option at coffee shops, due in part to marketing campaigns that note its smoother, less bitter taste. Not to mention that in the summer, this is a popular option when coffee lovers need their daily coffee but want to avoid the excess heat. Unlike coffee brewed relatively quickly at hot temperatures, cold brew is brewed slowly at low temperatures, with the coffee steeping longer within the water. Various health claims have been made about cold brew coffee, some by coffee enthusiasts and others by popular coffee companies, but not much is known about cold brew, and not enough information is out there yet to verify these claims.
Researchers at Thomas Jefferson University in Philadelphia, PA, wanted to collect some information about cold and hot brew coffees, to see if any of the claims made by bloggers, magazines, coffee companies, among others, may actually be true. They wanted to know how the acidity and antioxidant activity of cold brew coffee compared to that of traditionally brewed hot coffee. Antioxidants are compounds found naturally in fruits and vegetables, that prevent a process known as oxidation. Oxidation would commonly produce compounds called free radicals, which can trigger damage to cells in the body. For this study, the researchers used a variety of pre-ground light roast coffees from Brazil, Ethiopia (Ardi and Yirgz), Colombia, Myanmar, and Mexico, all purchased from a commercial vendor.
They freshly brewed coffee for each experiment, using the same coffee to water ratio in both cold and hot brewed coffees. For cold brew, they simply added 35 grams of coffee to 350 mL of filtered water in a mason jar and brewed for 7 hours at room temperature before filtering through a paper coffee filter. For hot brew, they boiled the water, then added the same ratio of coffee grounds to water to a French press carafe and brewed for 6 minutes before filtering through the same type of paper coffee filter.
With hot brew coffee, the researchers measured the pH with a standard pH meter, and found values ranging from 4.85 (Ethiopian coffees) to 5.10 (Brazilian coffee). To determine the amount of acids in each coffee, they titrated (slowly mixed) the hot brew coffee with sodium hydroxide to pH 6 and pH 8. The amount of acids in coffee could influence the level of bitterness tasted. With this method, the Colombian coffee was found to have the highest amount of acidic compounds at both pH values, while Brazil and Myanmar coffees had the lowest.
Antioxidants were counted using an instrument called a UV-Vis spectrometer. With their method, they compared the coffee sample containing antioxidants of an unknown concentration to standards with known concentrations. The Ethiopian hot brew coffee had the most antioxidant activity, while the lowest again belonged to the Brazilian coffee.
When the researchers switched to the cold brew coffee, pH ranged from 4.96 (Ethiopian) to 5.13 (Myanmar), which was quite comparable to the hot coffee. Colombia again had the highest concentration of total titratable acids at pH 6, but the Brazilian coffee had the highest at pH 8. Of these, Ethiopian-Ardi had the highest antioxidants, and Myanmar and Ethiopian- Yirgz had the lowest.
Overall, the water temperature had a strong influence on acidity and antioxidant activity. pH for both cold and hot brew were very similar. The researchers found that while hot coffee had more acidity by the titration method than cold brew, the hot coffee also had higher antioxidant activity. While this study showed that hot brewed coffee was more acidic, the researchers suggest that these acidic compounds might be responsible for the higher antioxidant levels. For all the coffee lovers out there: more work needs to be done to assess the health benefits of drinking hot coffee compared to cold brew coffee. Scientists don’t yet know the health effects of coffee when brewed at different temperatures or times, or how the antioxidant level in cold brew influences any of the protective benefits previously known to be associated with hot brew. In the meantime, whether you enjoy your coffee brewed hot or cold, enjoy the flavor and extra boost of energy that it gives!
Next time you badly need a coffee, don't drink it, just think about and that's going to be enough. Smell the coffee and your experience will be even more intense. That's a scientific study, if you think this is a joke.
For millions of us, the day begins with at least one cup of coffee to jump-start our brains into productivity. We think clearer, move faster, and interact with coworkers (also drinking coffee) like we’re meant to work together – at least for a little while.
What if we could benefit from some of those effects by simply experiencing cues that make us think of coffee? That’s the topic of a new study, the latest in the ongoing scientific fascination with our favorite legal drug.
"People often encounter coffee-related cues, or think about coffee, without actually ingesting it," said lead author Sam Maglio, an associate professor at the University of Toronto’s Rotman School of Management. "We wanted to see if there was an association between coffee and arousal such that if we simply exposed people to coffee-related cues, their physiological arousal would increase, as it would if they had actually drank coffee."
The “arousal” in this case is a well-studied dynamic in which specific brain areas are activated by exposure to stimuli. Drinking coffee delivers a dose of caffeine that chemically arouses the brain into a state of alertness, but we also know that non-chemical cues, anything from certain colors to sounds to smells, can trigger shades of the effect.
To test the arousal potential of coffee without actually drinking it, the researchers conducted four experiments in which they exposed people from both western and eastern cultures to coffee and tea-related cues that would make them think of the substance without ingesting it.
The researchers were specifically interested in an effect known in psychology as “mental construal,” the degree to which we think in more or less concrete and specific terms. In an alert state of mind, the brain grasps whatever problems we’re facing more concretely – we get to the details that matter the most faster, allowing us to focus on solutions.
Across the experiments, the researchers say they found evidence that priming people with coffee cues—exposing them to images and other stimuli that conjured thoughts about coffee—did increase their mental construal, and also made them perceive time as shorter. An hour seemed to zip by faster with coffee on the mind.
The effects didn’t hold up as well for people from eastern cultures, in which the devotion to coffee isn’t as strong as in the west.
These results line up well with those from another recent study finding that simply smelling coffee increases alertness and sharpens thinking. In that study, a group of students taking the math section of the Graduate Management Admissions Test (GMAT) were exposed to coffee aroma. Compared to test-takers who didn’t smell coffee, the coffee group ended up with significantly higher test scores. They also reported greater expectations of doing well on the test while taking it, suggesting that the coffee aroma was triggering an ongoing uplifting effect throughout the test session.
All of these triggered effects likely tie back to the chemical effect of drinking coffee – our brains are “conditioned” to respond to coffee in certain ways (think of Pavlov’s famous dogs), so even brief exposure to coffee cues triggers the chemical-response pattern. These cues can’t deliver nearly the same level of effect as drinking coffee, but it seems we can experience flavors of it.
One useful takeaway from these studies could be to experiment with different ways of benefiting from coffee during the day without drinking it after the morning cup. Keeping coffee beans handy to sniff for a quick alertness boost, for example. Since we know that drinking caffeinated coffee later in the day can disrupt sleep, getting some of its benefits without continuously drinking it sounds like an idea worth trying.
The latest study was published in the journal Consciousness and Cognition.
I love coffee, it has to taste good. I love espresso, people think I am snob, but I'm not. I like to drink good coffee, fine-cuisine desserts that are not overly sweet, a glass of good wine, and overall, I prefer quality to quantity. However, I totally got this funny story, and I'm sure you'll love it too.
Decaffeinated against my will
I love coffee.
Nothing fancy, just a good dark roast with no room for cream. Ever since college, I have had a cup of coffee in reach.
It is my treat, my writing fuel, my liquid security blanket.
The only time I’ve given up coffee was while pregnant and when nursing my babies. I remember clearly the last time I nursed my last baby. Once done, I laid her gently in her crib, went straight into the kitchen and put the coffeemaker back on the counter.
That was 17 years and roughly 37,000 cups of coffee ago.
My friends and family no longer ask if I want a cup of coffee. They just hand it to me. Maryann Angelo, the wonderful owner of Barista Blues, hands me a carafe instead of a cup when I eat there.
Do I get headaches?
Do my hands shake?
Do I have manic periods where I can’t type as fast as my brain is thinking?
I know this bad, which is why I rejoice when studies come out lauding the health effects of coffee. It’s rich in antioxidants. It fights depression. It’s been shown to reduce the risk of diabetes, Alzheimer's and dementia.
These findings help me fend off the fact that one day some doctor is going to tell me to cut back. Not even the most liberal study would recommend the daily amounts of coffee I imbibe.
Sure enough, a few weeks after I turned 46, I was in a doctor’s office, holding a magazine, while a specialist asked me the “caffeine” questions.
“Do you drink energy drinks?"
My face when pink.
Now the magazine was over my face.
“How many cups a day?”
I’m not sure exactly.
Let’s just say my husband and I brew 12 cups of coffee in the morning and split the pot down the middle. And some days I drink one more cup before dinner.
When I lowered the magazine the doctor’s mouth was a thin line. She told me I needed to cut back my intake.
How far back?
To my credit, I didn’t cuss. The doctor did suggest I reduce my intake slowly, to avoid headaches. I moped all the way home, wondering if I had to switch to (gasp) herbal tea.
How am I supposed to write the great American novel on herbal tea?
My non-coffee-drinking son was the first human to cross my path after the bad news. I told him about the coffee problem.
“So, why don’t you just drink decaf?”
Decaf? I don’t put cream and sugar in my coffee because I want it to smell and taste like coffee. Decaf doesn’t smell and taste like coffee.
Later, I moped around the Internet looking at decaf coffees. I found other coffee snobs who had to get off the juice. These were my people, folks whose pain I felt. They wrote exhaustive reviews on decaf coffees, giving me a couple of recommendations, one of which I bought begrudgingly.
My plan was to reduce the good stuff and use the fake stuff for emergencies. I was not excited about this plan, which is why I had yet to brew the decaf, despite suffering a few emergencies.
That Friday, I went to visit family for a couple of days. I tried to be good about sticking to two cups of coffee a day. When I returned, my husband was nursing a cup of coffee and a headache. He wondered if he was getting sick.
I went into the kitchen and saw he had brewed my decaf by mistake. He wasn’t sick, just under-caffeinated. Before telling him so, I had to ask.
Did the coffee taste good?
No, it has nothing to do with pot, THC, or CBD. However, this interesting scientific study discovered that coffee affects our ability to produce endocannabinoids. This is probably how we get the caffeine boost. This would also explain why many stress-related disorders are more prevalent while drinking coffee. No, I will not give up the stuff, if you ask me. I'll just chill more.
Coffee’s Effect On The Endocannibinoid System
BUSTED! You saw “endocannabinoid” in the headline and you just came running. We’re telling your parents, Holden Caulfield. But while we’re totally ratting you out, we can also explain to your folks that new research finds a link between coffee consumption and a drop in the number of neurotransmitters in the endocannabinoid system, the opposite effect of those “tomato plants” you are growing in your closet that you told your mom are for the science fair.
Published in Journal of Internal Medicine, the study is the work of lead author Marilyn Cornelis, an assistant professor of preventive medicine at Northwestern University Feinberg School of Medicine. According to Science Alert, Cornelis et al took 47 coffee drinkers and had them quit consuming coffee for a 30-day time period. These 47 participants would then drink four cups a day for 30 days, followed by eight cups daily for another 30 days. At each stage of testing, researchers would take blood samples from the participants to measure and analyze “changes in biochemistry that result from consuming food and drink.”
The resulting profile revealed 115 metabolites were impacted by the consumption of coffee. A total of 82 of those chemicals were already known, and could be mapped to 33 metabolic pathways, a number of which were completely new relationships.
One of these noted effects was to the endocannabinoid system. According to the article, the endocannabinoid system affects everything from cognition to sleep to appetite. Consuming cannabis increases the number of endocannabinoid neurotransmitters, and in times of stress, the human body “tends to decrease its production of endocannabinoids.” This study found that coffee consumption had an effect similar to that of stress.
It may not be the coffee consumption per se causing the stress, but the drastic changes in consumption asked of the study’s participants. “The increased coffee consumption over the two-month span of the trial may have created enough stress to trigger a decrease in metabolites in this system,” Cornelis states. “It could be our bodies’ adaptation to try to get stress levels back to equilibrium.”
The study also found a link between drinking coffee and the metabolic pathway keeping steroid levels in check, which could have an effect on “everything from growth to sexual characteristics.”
Thus far, the study only goes to show that there is a link between drinking coffee and the endocannabinoid system; the exact interaction has yet to be established. The next step, according to Cornelis is to “delve deeper and study how these changes affect the body.”
So whenever your parents find the espresso machine hiding under your bed, let them know you need it to regulate your endocannabinoid levels. You’ve been eating a lot of tomatoes.
Alcohol is bad for you. Coffee is bad for you. Apparently NOT!
If you want to live a long life, you have to ditch alcohol and coffee. We heard that many times, and we ignored it or not. New research shows that if you want to live into your 90s you should not give up on coffee and alcohol.
Well, the research shows that people who have two alcohol servings per day and two cups of coffee get to live more. In all fairness, we don't know if alcohol and coffee are the cause, or the fact that we better genes help us drink more of the stuff. Anyway, the research is interesting...
Cheers! And hell yes – a new study has found that consuming moderate amounts of both caffeine and alcohol may help you live into your 90s.
After you’ve finished jumping up in down in celebration, and then running to the store to buy wine and coffee, here’s some more information:
According to researchers at the UC Irvine Institute for Memory Impairments and Neurological Disorders, drinking two servings of alcohol daily decreased chances of premature death by 18 percent, while drinking two cups of coffee each day decreased premature death by 10 percent.
The study, called the 90+ Study, has looked at information from over 1,600 nonagenarians since 2013 in order to determine what may contribute to longevity and long-term health. All of the participants (called “the oldest old”) see a doctor twice a year, answer questions about their lifestyle and health, and undergo a number of physical and neurological tests. And this latest finding is freaking amazing.
“I have no explanation for it, but I do firmly believe that modest drinking improves longevity,” Dr. Claudia Kawas, one of the study’s lead researcher, said at a recent scientific conference.
And that’s fine with us – we don’t really care why it’s true.
If you can even believe it, this wasn’t even the only good news to come out of the 90+ study so far. Researchers also found that people who were moderately overweight in their 70s were much more likely to live into their 90s than those who weighed less.
The study has also found that while a little extra padding can help you enjoy a long life, regular exercise is also key to sticking around on earth. So is having a regular hobby to keep you mentally sharp and healthy. Specifically exercising for 15 to 45 minutes each day reduced the risk of early death by 11 percent, while those who spent 2 hours on a hobby daily had 21 percent reduced risk of early death.
In other words: if wake up and drink coffee, spend some time doing something you love, make sure to go on a walk, eat a cookie, and have some wine with dinner, you can basically live forever.
One thing to note: all of these findings involve the word moderate. Heavy drinkers didn’t fare well, and neither did drinking tons of coffee. And while a few extra pounds makes your heartier in your 70s, being obese wasn’t connected with a longer life.
Of course, not all of the findings are great. One of the tidbits discovered by researchers is that living into your 90s might not be the greatest thing ever, because over 40 percent of those who get past 89 suffer from some form of dementia, while almost 80 percent are living with a disability (and the numbers are even higher for women).
And another little warning: while drinking caffeine and alcohol in moderate amounts may be a-okay, drinking caffeine and alcohol together might not be the best thing in the world. Why? Coffee can mask the depressant aspects of alcohol, making people more alert as they drink and perhaps allowing them to drink more than they would. Also, it’s a myth that coffee helps sober you up if you’ve been drinking. So, maybe space out your morning and evening mind-altering beverages.
Finally – the 90+ study is looking for more participants. If you know someone who might be interested, they can call 949.768.3635.