When we founded Purity Coffee in 2015, we were committed to creating coffee with positive health outcomes as our key principle. We spent over a year studying the health benefits of coffee and ways to achieve optimal levels of different compounds. From conscious sourcing of several different cultivars, through roasting and packaging, we focus on health without compromise. We continue to look for the best coffees and research ways to make our coffee even healthier. This was (and is) our commitment to our customers.
As Purity Coffee received constructive and encouraging feedback from our customers, we were inspired to continue studying. Coffee is extremely complex, and various beneficial compounds can be created and destroyed at different roast levels. Therefore, it is imperative that we continue to strategically roast in a health focused manner.
Purity Dark Roast: Following the Science
Why Dark Roast? Why Now?
When choosing to roast for health, inevitably we must decide the compounds on which to focus. How do different roast levels of the same coffee have different compounds? The answer is dependent upon temperature, time, heat application at different critical points, and ending the roast at the right time. This is what we call the roast curve or profile. Our dark roast follows a profile laid out in the scientific literature (please see references) and hits several points that have been proven to be critical. Our coffee’s standards haven’t changed, but the compounds we’re looking for in roasting have expanded.
When Purity Coffee first found the right type of green coffee, we focused on maximizing antioxidant compounds (primarily chlorogenic acids) and minimizing harmful compounds (mainly acrylamide and PAHs). Our research has identified a new roasting profile which adheres to the same standard (please see quality standards here) that we use in our original roast.
There are many ways roasters describe a coffee’s color, and most terms are not precise, but rather suggestive.
Purity’s original coffee is a medium roast, which is a bit darker than the industry’s sample roast level to evaluate (or “cup”) specialty coffee. Purity’s dark roast is darker than medium, and what some might say is a “Full City” roast. It is NOT as dark as what many consider Italian or French roast because our standards will never allow PAH to be created during roasting.
Revisiting Familiar Compounds: Pros/Cons of Dark Roast
When we developed Purity Dark Roast, we lab tested blends of our green coffees roasted to different profiles. After testing them we defined the best blend with the ideal roast curve. When comparing Purity Dark Roast to Purity Original, here are a few points to consider:
Chlorogenic Acids (CGA)
Of all plant constituents, coffee has one of the highest concentrations of chlorogenic acids. Because of the high content of chlorogenic acids, coffee is considered the most important contributor to antioxidant intake in many populations, since people routinely drink it and, in many cases, multiple times a day. The most significant health compounds impacted by roasting are these chlorogenic acids.
- PRO: Dark roast still contains chlorogenic acid lactones and melanoidins, which have antioxidant properties.
- CON: All research indicates that total free chlorogenic acid content decreases as the coffee is roasted to a darker level. This in turn impacts antioxidant activity of those particular polyphenols. If these are the most important health compounds of coffee for you, then stick with original Purity Coffee. Purity Dark Roast still has antioxidant capacity, but total CGA is about half the original.
- PRO: Chlorogenic acids may stimulate gastric fluid secretions in some people, and for these people a darker roast may be a better choice. Generally, throughout the literature, dark roast appears to be an appropriate choice for individuals with digestive issues. The dark roast has less acidity, and may be more beneficial for those who feel that acid bothers them. For more information on dark roast, acidity and the gut refer to (a whole other topic).
Acrylamide and Polycyclic Aromatic Hydrocarbons (PAHS)
It is important to avoid creating, as much as possible, a few compounds from chemical reactions that occur during the roasting process (primarily acrylamide and polycyclic aromatic hydrocarbons [PAHs]).
- PRO: Acrylamide decreases the darker coffee is roasted. Purity Dark Roast has even lower acrylamide than Purity Original.
Acrylamide is formed during a process known as the Maillard browning reaction in coffee and many other foods. Acrylamide was associated with cancer from one study using lab rodents exposed to extremely high concentrations, thousands of times higher than a cup of coffee. Other studies showed no direct evidence of cancer risk, and when the FDA reviewed the literature, it stated that coffee should be exempt from the discussion.
- PRO: Purity Dark Roast coffee does not come close to PAH temperatures. Even at the highest temperature before we take the coffee out of the roaster, it has spent significantly fewer than 15 minutes from 200°C to 230°C.
PAHs are formed from pyrolysis (the chemical decomposition of organic material by application of heat), when coffee is roasted to extremely high temperatures. Roaster temperatures should be lower than 240°C (464°F) for 15 minutes in order to avoid the formation of PAHs. (Vegas, 2019). We believe the US FDA and European Union should place a maximum limit for allowable PAHs in coffee and so we choose to avoid PAHs as much as possible.
These three compounds are only a small part of coffee’s story. The literature has pulled us deeper into many other coffee compounds that impact health.
Key Compounds for Dark Roast
- Chlorogenic Acid Lactones
- Trigonelline, Niacin and N-methylpyridinium
Below is a chart that summarizes key points, which are explained in more detail.
|Summary of Key Findings in Dark Roast Coffee|
|Component||Significance||Effect of Roast||Reference|
|Melanoidins||Melanoidins are what make coffee (and foods) brown when roasted, baked or toasted. Coffee melanoidins may enhance immune stimulating properties, serve as dietary fiber, and may contribute to reducing the risk of colon cancer.||High molecular weight melanoidins are formed as roasting gets darker. Melanoidins have metal chelating properties (antioxidant activity).|
Melanoidins may decrease colon inflammation through improved microbiota balance (prebiotic effect). Dark roasted coffee shows promotion of Bifidobacterium [BB12], a well known probiotic, via melanoidins as the main substrates.
Fogli ano and Morales, 2011.
|Trigonelline & Niacin||Trigonelline is a plant hormone and product of niacin metabolism in the plant. Trigonelline plus nicotinic acid helps regulation of liver enzymes, which is closely related t o the suppression of triglyceride accumulation as well as progression of diabetes.||As coffee is roasted, the content of trigonelline decreases and niacin increases. In the coffee beverage, this niacin is highly bioavailable.|
Niacin (nicotinic acid) is essential for specific oxidation reduction reactions in the body. It has been shown to reduce some neurological disorders, such as dementia.
Farah, 2005 & 2009.
|N-methylpyridinium||Formed during roasting from trigonelline as a non volatile degradation product.||Dark roast has higher N-methylpyridinium.|
Gastric acid secretion lower after consuming dark roast blend coffee compared to the medium roast blend.
N-methylpyridinium rich, dark roasted coffee reduced the bodyweight in pre obese subjects.
CGA and N-methylpyridinium were identified as inducers of Nrf2, considered the master regulator of cell survival.
Potential DNA protective effect.
Pahlke, 2019 and Schipp 2018.
|Chlorogenic Acid Lactones||Antioxidant activity, anti opioid activity, hypoglycemic, and potential effects on brain function independent of the pharmacological effects of caffeine.||Chlorogenic acid lactones (CGL) are created during the coffee roasting process from chlorogenic acids (CGA).|
As with CGA, a fraction of CGL is absorbed in the digestive tract. The remaining amount is metabolized by the gut microbiota and the metabolites (phenolic acids) with antioxidant and anti inflammatory activities can still be absorbed or protect the colon from free radicals.
|Farah, 2005 & 2013.
Díaz Rubio, 2007. Note: A dark roast mixture was used in this study.
|β-carbolines||Roasted coffee is the major known food source of norharman and harman β carbolines. They are MAO inhibitors, being increasingly associated with a beneficial effect in Parkinson disease. Scientists study these compounds with caution, however.||Amounts of harman and norharman levels are very low in green coffee and increase significantly during roasting, but are highly variable. It is indicated that a darker roasted coffee will be higher in harman and norharman β-carbolines.||Casal, 2015.
What they are: Melanoidins are what make coffee (and other foods) brown when roasted, baked or toasted. They are formed during the Maillard reaction, when sugars and amino acids combine at high temperatures and low water activity. They may be considered bioactive compounds (Bekedam, E.K., et. al., 2008). The extent of roasting induced antioxidant formation is directly linked to the extent of melanoidin formation, and the longer we roast, the more intermediate and high molecular weight melanoidins are produced.
Impacts / Actions: Antioxidant activity, metal chelating, antibacterial, prebiotic functionality.
Details and References:
- Coffee melanoidins may act as soluble fiber enhancing immune-stimulating properties and contributing significantly to reducing the risk of colon cancer (Vitaglione, 2012; Moreira, 2015; Fogliano, 2011). This likely happens by decreasing colon inflammation through improved microbiota balance (prebiotic effect) and by increasing the elimination rate of carcinogens through higher colon motility (urge to use the bathroom).
- Coffee melanoidins do not seem to be absorbed in humans, but they can function as an antioxidant dietary fiber with an overall antioxidant capacity via embedded low molecular compounds. Melanoidins can act like a ‘sponge’ for free radicals in the gut (Garsetti, 2000; Folmer, 2017). This improves the reduced/oxidized glutathione balance in the colon. Glutathione is an antioxidant produced in our cells.
- Coffee melanoidins seem to have a protective effect on liver steatosis in obese rats (Vitaglione, 2012), which suggests that the melanoidins in coffee may have an influence on liver fat and functionality. Glutathione may be involved.
- Coffee melanoidins inhibit lipid peroxidation. Increasing evidence shows that oxidized lipids, advanced lipid oxidation end products, and lipid peroxidation play a major role in developing most oxidative stress-related diseases. Lipid peroxidation occurs in all human neurodegenerative diseases, such as Alzheimer’s disease, Parkinson disease and even atherosclerosis (Tagliazucchi, 2010).
- Coffee melanoidins are able to chelate transition metal ions, that is they are able to bind Zn2+, Cu2+, and Fe2+ (Takenaka, 2005; Morales, 2005). Metal-chelating ability is key to inhibiting lipid peroxidation, among other benefits.
- Coffee melanoidins may act to promote the growth of a beneficial colon microbiota, affecting inflammatory pathways in the colon and consequently in the liver (Folmer, 2017). Oddly, antioxidative structures formed in coffee melanoidins are similar to vitamin E. These appear to activate their scavenging properties gradually (Bekedam, 2008).
- Several studies carried out have shown that melanoidins extracted from coffee possess antioxidant activity. The antioxidant activity of melanoidins isolated from different brews was studied, and some showed that the radical scavenging ability of coffee melanoidins was higher in the dark-roasted coffee, others exhibited higher radical scavenging activity, and still others showed radical scavenging ability of coffee melanoidins was not affected by the degree of roasting (Tagliazucchi, 2010).
Chlorogenic Acid Lactones:
What they are: Chlorogenic acid lactones (CGL) are bitter compounds with antioxidant capacity created during the coffee roasting process from dehydration of chlorogenic acids (CGA).The maximum amount of CGL represents approximately 30% of the available original CGA amount (Farah, 2005).
Impacts / Actions: Antioxidant activity, possible anti opioid activity, hypoglycemic, and potential effects on brain function independent of the pharmacological effects of caffeine.
Details and References:
- CGL exhibit opiate receptor binding activity with characteristics like those of opiate antagonists and can reverse morphine-induced analgesia in mice. However, acute pharmacologic effects are unlikely with normal coffee consumption. Like chlorogenic acids, these compounds are partly absorbed (Farah and DePaula, 2019).
- Part of the lactone was converted into caffeoylquinic acids after contact with the alkaline pH of human digestive fluids. Therefore, it is likely that a large proportion of these lactones consumed in the brew return to their respective chlorogenic acid forms during digestion, indirectly increasing the total chlorogenic acids intake (Farah, 2013).
- Chlorogenic acid lactones were shown to exert blood glucose-normalizing effects in rats, and these effects were later observed for the chlorogenic acids themselves (Farah, 2013).
- It has been found in a mouse model that chlorogenic acid affects spontaneous locomotor activity, suggesting that chlorogenic acid or its metabolite could pass the blood-brain barrier. The chlorogenic acid lactones are less polar than their parent compounds and should be more permeable to the blood-brain barrier. One study showed a significant correlation between the levels of chlorogenic acid lactones in coffee and neuron cell survival. This suggests that chlorogenic lactones might contribute to the increased protective effects against H2O2-induced death of neuron cells (Chu, 2009).
Norharman and Harman B-carbolines
What they are: Roasted coffee is the major known food source of norharman and harman β-carbolines. Considered mostly as neuroactive substances with a wide spectrum of reported pharmacological and neuroactive actions, binding to many receptors in the brain, including opiate, and frequently act as inhibitors to regulate neurotransmitters. So far only norharman and harman β-carbolines have been reported in coffee (any reference in this review to β-carbolines refers to only these two). Their health effects are being extensively studied.
Impacts / Actions: Antioxidant activity, possible anti opioid activity, hypoglycemic, antidepressant. Reduced rate of development of Parkinson’s disease (Ascherio, 2004).
Details and References:
- Norharman and harman are potent competitive and reversible monoamine oxidase (MAO) inhibitors, in both rat and humans. The high amounts of these β-carbolines in roasted coffee place them in the top of the suspected list for compounds with probable influence on Parkinson’s disease course (Casal, 2015)
- Amounts of harman and norharman levels are very low in green coffee and increase significantly during roasting, but are highly variable. It is indicated that a darker roasted coffee will be higher in harman and norharman β-carbolines (Gomes, 2006).
- Norharman and harman extracted from coffee brews exhibited inhibitory properties on recombinant human MAO-A and -B isozymes, catalyzing the oxidative deamination of kynuramines (Herraiz, 2006).
- The amounts produced during roasting are variable, but generally speaking, norharman increases during roasting and harman decreases after 240°C (464°F) (Casal, 2015).
Trigonelline and N-methylpyridinium:
What it is: Trigonelline is a plant hormone, one of the more abundant sources of nitrogen in green coffee, and a product of niacin metabolism. Green coffees contain about 1% trigonelline, of which 50-80% is degraded upon roasting, and it breaks down to niacin and nicotinic acid and N-methylpyridinium at higher temperatures, as well as volatiles such as pyridine and pyrazines.
Impacts / Actions: Antioxidant activity, anti-tumorigenic, anticarcinogenic, anticariogenic, antimicrobial, hypoglycemic, hypocholesterolemic.
Details and References:
- Trigonelline at the dark roast level converts to higher niacin levels. In the coffee beverage, this niacin is highly bioavailable (Trugo, 2003). Niacin (nicotinic acid) is essential for specific oxidation–reduction reactions in the body.
- Trigonelline plus chlorogenic acids reduced early glucose and insulin response, which helps prevent type 2 diabetes (Viera, 2019). Trigonelline plus nicotinic acid helps regulation of liver enzymes, which is closely related to the suppression of triglyceride accumulation as well as progression of diabetes.
- Trigonelline acts on up-regulating antioxidant enzyme activities and decreasing lipid peroxidation in the pancreas (Verzelloni, 2010).
Note: Volumes have been written about trigonelline, but for this paper the research purpose was the relationship between dark roasting and trigonelline. Trigonelline is an effective compound in prevention of diabetes and related kidney diseases (Virtanen, 2019). The content of trigonelline decreases continuously throughout roasting, while nicotinic acid and N methylpyridinium increases, with N-methylpyridinium being the major thermal product up to the dark medium roast, similar to the Purity Dark Roast.
What it is: N-methylpyridinium is formed during roasting from trigonelline as a nonmethylpyridinium is formed during roasting from trigonelline as a non–volatile degradation product. While small amounts of trigonelline and nicotinic volatile degradation product. While small amounts of trigonelline and nicotinic acid are present in many foods other than coffee, the ocacid are present in many foods other than coffee, the occurrence of Ncurrence of N–methylpyridinium in our daily diet seems to be restricted to roasted coffee methylpyridinium in our daily diet seems to be restricted to roasted coffee (Viera, 2019).(Viera, 2019).
Impacts / Actions: Antioxidant activity, lower stimulatory effect on gastric acid Antioxidant activity, lower stimulatory effect on gastric acid secretions, possibly assists in weight control, anticarcinogenic (possibly with secretions, possibly assists in weight control, anticarcinogenic (possibly with colon cancer), DNA protective effects.colon cancer), DNA protective effects.
Details and References:
- Gastric acid secretion was less effectively stimulated after administration of a dark roast blend coffee compared to the medium roast blend. The dark roast measured higher concentration of N-methylpyridinium 87 mg/l compared to the medium roast (29 mg/l), but lower trigonelline and CGA (Rubach, 2014).
- A N-methylpyridinium-rich, dark roasted coffee reduced the bodyweight in pre-obese subjects, indicating a significant potential for body weight control by dark roast coffee brews containing high amounts of NMP (Kotyczka, 2011).
- CGA and N-methylpyridinium were identified as inducers of Nrf2, considered the master regulator of oxidative stress. Nrf2 represents one of the main cell defense mechanisms and major regulators of cell survival. N-methylpyridinium represented an even more potent extract in vitro and in vivo than CGA (Boettler, 2011).
- Numerous studies indicate that damage of the genetic material plays a crucial role in a variety of human diseases, in particular in the etiology of cancer. Chronical consumption (8 weeks) of a pure arabica dark-roast coffee blend significantly reduced spontaneous DNA strand breaks in blood cells of healthy volunteers, pointing to a DNA protective effect (Pahlke, 2019) and (Schipp 2018).
- A strong increase of the activity of N-methylpyridinium, which catalyzes the detoxification of numerous genotoxic carcinogens, was observed in the liver. In addition, a pronounced increase of the antioxidant activity of plasma was detected in experiments, indicating that N-methylpyridinium may contribute substantially to the ROS protective properties of coffee (Al-Serori, 2019).
More to Come…
The literature clearly states more research needs to be done in humans on these issues. There are so many studies, that we have the potential either to refine the dark roast to match future literature, or come up with an additional roast based on findings by the researchers.
In particular, because norharman and harman β-carbolines and N methylpyridinium are unique in coffee, these may yield more information in the areas of mental health and gastrointestinal benefits, respectively.
Depression, Cognitive Decline, Alzheimer’s and Parkinson’s Diseases
A vast number of papers have been written on coffee’s impact on the brain and mental health. Coffee can influence cognitive functioning , improve memory and protect the brain’s oxidative system. Some of this is roast level dependent. Purity Coffee will continue to explore how:
- Dark roast coffee extracts are more potent inhibitors of amyloid beta oligomerization (the main component of the amyloid plaques found in the brains of people with Alzheimer’s disease) than light roast coffe e extract. Phenylindane, found in dark roast, is a potent inhibitor of both amyloid beta and tau fibrillization. (Mancini, 2018)
- Parkinson’s disease is the second most common neurodegenerative disorder, affecting 1% of the world population age 65 and older. Regular coffee consumption has been epidemiologically associated with a reduced risk for Parkinson disease, particularly in regard to the caffeine. (Chen, 2019). However, the compounds in dark roast that are shown to be beneficial for Alzheimer’s disease are also being investigated for Parkinson’s. That said, the concern with Parkinson’s points to extremely dark roasted coffee.
- The results indicated that the intake of coffee, similar to caffeine, improved long term memory when tested with object recognition. In addition, chronic coffee and caffeine ingestion reduced the lipid peroxidation of brain membranes and in creased the concentration of reduced glutathione. Chronic coffee ingestion, through the protection of the antioxidant system, may play an important role in preventing age associated decline in cognitive function. (Abreu, 2011).
- The sensory characteristics of dark roast coffee (roast aroma and flavor, burnt aroma and flavor, bitter, and body) might elicit positive high energy feelings for some. Tobacco (flavor) and cocoa (aroma) may also be responsible for positive emotions (content, good, and pleasant). Citrus and acidity seemed to be negative sensory drivers as they induced the feeling of being off balance (Bhumiratana, et. al 2019).
Additional Notes on the Literature
While digging into the peer reviewed articles, we found a few observations and concerns we would like to point out. Purity will continue to keep an eye on the research that addresses these issues:
- Coffee is so complex, that when studying certain compounds, it bears repeating that most beneficial effects of coffee are produced by the combined action of different bioactive compounds that make up a given coffee. This is one reason why scientists seem hesitant to proclaim a certain nutrient as champion. As Mancini (2018) points out, “The neuroprotective effect of coffee consumption is likely due to a combination of factors.” The cocktail of compounds works concurrently to impact positively a range of human health conditions.
- Intermediate and high molecular weight melanoidins do not appear to be digested or taken up in the blood stream at all. There is not much information available on the bioavailability of coffee melanoidin antioxidants, and melanoidins have low digestibility. It is likely that coffee melanoidins will pass the GI tract , and if the antioxidants are not destroyed by gastric conditions, the roasting induced antioxidants should show antioxidant activity. This could provide protection against a wide range of radicals throughout the GI tract, but more research needs to be don e (Bekedam, 2008).
- The roasts used in the Boettler study were very different than what Purity would ever consider using. Their dark roast was done extremely quickly and to too high a temperature. In addition, the conclusion admitted that although there appears to be an impact on the Nrf2 pathway, there actually was no significance statistically. Also, all studies were supported by the same company, so may have had a financial interest stake in its results, i.e. conflict of interest.
- Scientists approach the study of β carbolines in coffee cautiously, due to their strong biological actions on the nervous system and coffee being a rich dietary source. Some propose that these compounds are involved in the pathogenesis of Parkinson’s and further studies are needed. Older studies (Ostergren, 2004) indicate that it is possible norharman may cross the cerebral barrier and accumulate in the cortex. The lowest roast level indicated in the study by Gomes (2006) was about 8°C (46°F) higher (that’s A LOT in coffee roasting) than Purity’s dark roast level. The Gomes study approached PAH levels too high above what Purity has set as its safe standard to avoid PAHs. The Purity Dark Roast β carboline level should be “in moderation” to have the beneficial effects indicated by the literature without going too far.
- Chlorogenic acid should be seen in light of their relative percentage in comparison with CGA. As coffee is roasted darker, CGA decline, but the lag time and temperature of CGL must be considered in terms of overall percent, when considering levels.
- Studies of β-carbolines in coffees are confounded significantly due to the common issues of studying coffee (cultivar, soil and inputs, growing conditions, processing methods, drying methods, storage time, roast level, etc.), but seem to have even wider swings of results than other compounds. The coffee brew method and water-to-coffee ratio is a major confounder, too (Rodrigues, 2019).
- There is still so much research to be done on roast level and coffee compounds, which is confounded by the vastness of coffee cultivars, farming practices, processing techniques, roasting machines and brew methods, that anything written here will need to be revised annually. Overwhelmingly, though, the literature points to coffee being good for health, and dark roast being helpful to (or easier on) the digestive tract.
- Everyone has a unique biome within, and people will have different responses to a given coffee.
What We Are Excited About
As more people choose to buy coffee for health, we are eager to learn more about coffee’s possibilities. Outside of the decisions we’ve made, there are so many things at play that we still don’t know, and scientists continue to provide insights. Here are our top 3 take aways:
- None of the research stated that they had used specialty grade (higher quality), certified organic coffee. We assume, then, that the coffee was likely commercial grade and conventionally grown. We can only imagine what results might be with a healthier coffee.
- The literature shows how there are dozens of choices Purity can make in roasting that positively impacts health. These findings support our vision to further develop coffees for different conditions. This gives more choice for consumers based on their health concerns.
- Purity works with producers who are committed to innovative farming techniques. These yield coffees that are among the healthiest we have ever tested, and they happen to also roast beautifully for taste. As we decide on coffees and roast levels, we can bring more health to the cups of our customers.
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- Al-Serori H., Setayesh T., Ferk F., Mišík M., Waldherr M., Nersesyan A. and Knasmüller S. (2019)DNA Protective Properties of Coffee: From Cells to Humans. Coffee: Consumption and Health Implications. A. Farah Ed., Ch.4, Royal Society of Chemistry
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