The Latest in Coffee Science: Observations from the 2021 ASIC Conference

The 2021 Association for Science and Information on Coffee (ASIC) biennial conference concluded in Montpellier, France, on July 1, and I’m feeling pretty lucky to have been able to attend, albeit remotely.

The Association’s 28th symposium was available to guests in video format due to the ongoing coronavirus pandemic — opening up a plethora of valuable information shared by some of the world’s leading scholars, academics, and professional researchers with interests surrounding coffee. 

When I attended in person in Portland, Oregon, in 2018, and took such copious notes that DCN had to split some 3,000 words into two separate articles (part 1 and part 2).

---

Related Reading

• SCA Launching Green Coffee Summit with August Event
• Colombian Researchers Discover Aggressive New Variants of Coffee Leaf Rust
• What Researchers Learned from the Remarkable Stenophylla Tasting

---

I’ll confess that this time around my attention to details was compromised by a severe case of Zoom fatigue plus time zone differences that forced me to attempt to grasp densely packed charts, technical information and heady lectures beginning at 4 a.m. local time. 

I have not yet  made my way through all of the scientific posters associated with the presentations, and I was unable to catch every last moment of the program due to simulcast schedule conflicts.

Given those caveats, I humbly present the following hodgepodge of casual observations and takeaways from the event. The subject of each seminar is listed in bold; the presenters are listed in italics; and my observations follow.:

Subject: Will it keep me awake? Common coffee / caffeine intake habits and sleep in real life situations

Presented by: Dr. Hans-Peter Landolt (Institute of Pharmacology and Toxicology – University of Zurich, Zurich, Switzerland)

My observations: Dr. Landolt reported on the effects of caffeine on sleep-deprived individuals and observed that:

• Caffeine had a small effect on a subjective “sleepiness scale” beginning at around 10 hours without sleep, and dramatically increasing effectiveness at around 24 hours continuing until about 40 sleepless hours, when the placebo and caffeine sleepiness realigned.
• Regular high caffeine intake (3+ beverages per day) does not seem to interfere with the restorative quality of sleep (1700+ participants reporting).

Global change: Adapting coffee pest and disease management

Prof. Karen A. Garrett and Aaron I. Plex Sulá (Plant pathology department – University of Florida, Gainesville, USA)

Garrett and Sulá noted that croplands with high interconnectivity should be aware of the interactions of multiple-disease relationships and their potential interactions. Regions of concern include Western El Salvador and Honduras, Andean Colombia and Ecuador, Southeast Brazil, Côte d’Ivoire, Uganda, Rwanda, Burundi, Sumatra, Southwest India and Southeast China.

A new (sensory and consumer) Coffee Brewing Control Chart

Jean-Xavier Guinard (UC Davis Coffee Center, University of California, Davis, California, USA)

Professor Guinard presented a newly designed “brewing control chart” based on consumer preference across metrics of TDS and Extraction percentage that newly includes certain flavor profiles such as citrus, bitter, sweet and others. More than 25 attributes were rated along various extraction profiles, and consumer preference landed in distinct groups:

• Consumer 1: low TDS & Extraction – prefer sweet simple coffees
• Consumer 2a: high TDS, low Extraction – prefer bright fruity coffees (presumed to be specialty consumers)
• Consumer 2b: moderate TDS, high extraction – prefer bitter, full, black-tea-like coffees

The conclusion was made that consumer preference does not alight with the current Coffee Brewing Control Chart, and dismisses the one-size-fits-all approach to “ideal” brewing.

The role of ethyl esters in green coffee: flavor or off-flavor precursors?

Valentina Lonzarich (Aromalab – llycaffè spa, Trieste, Italy)

Lonzarich noted that ethyl ester formation can occur under many fermentation conditions, as well as under elevated moisture and temperature levels during shipping and storage. These esters are present in high concentration in “stinkers.”

Lonzarich concluded that ethyl ester concentration is insufficient to distinguish between intentional practice versus “incorrect” processing.

Lonzarich proposed an objective criterium for “over-fermented off-flavor and deeply fruity flavor” to be a threshold of some ethyl esters in green coffee beans, including certain esters at a target of zero (such as is currently used in other food products like virgin olive oil).

The molecular code of coffee aroma and taste

Prof. Imre Blank (Coffee Excellence Center – ZHAW, Zürich, Switzerland)

Professor Blank produced a wonderfully complicated biochemical analysis of certain bitter compounds in roasted coffee and how they influence preference and cup scores.

This included four “highly predictive chemical compounds” that were associated with high cup scores. It was noted that these compounds didn’t have specific flavor attributes associated with them, but rather that they are “flavor modifiers.”

Blank explained that diacetyl, the chemical compound most often associated with a positive “buttery” taste in coffee, naturally occurs during two stages of roasting:         

• Early in the roast it develops from sucrose shell structure
• Later in the roast it is produced by reassembly of sugar fractions

Coffee bean particle motion: implications for heat transfer during roasting

Mark Al-Shemmeri (Jacobs Douwe Egberts, Banbury, United Kingdom)

Al-Shemmeri produced a fascinating graph of bean movement in a fluid-bed roasting environment, including velocity and trajectory, while noting various implications of a dense “bean-bed” versus the more fluid “freeboard” of lofted beans.

He observed, anecdotally, the importance of the green coffee’s density as a factor in performance, but did not take it into account in his analysis.

A single polyploidization event at the origin of the tetraploid genome of Coffea arabica is responsible for extremely low genetic variation in wild & cultivated germplasm

Michele Morgante (Istituto di Genomica Applicata, Udine, Italy)

Morgante proposed that arabica’s spontaneous “birth” was a one-time event — a single progeny from a single inter-species mingling of canephora and eugenioides, dated approximately 20,000 years ago. The event would have been responsible for the entire arabica population; ergo, it could also account for arabica’s lack of genetic diversity today.

A new method for measuring early time scale coffee extraction kinetics in a well-stirred batch reactor

Matthew Maille (Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK)

Maille’s association with Keurig Dr Pepper led him to examine the importance of extraction in the very early seconds of brewing, a timeframe that has received very little scientific focus:

• In a submerged, dynamic, dilute brewing environment, malic acid was seen to extract to more than half of its final concentration within the first 5-10 seconds.
• This extraction was shockingly not dependent on the size of the grind particles.
• Interestingly, it appeared from the data that caffeine was more sluggish in extraction (though still significant in the first 10-20 seconds) and that there was a delay of roughly 5 seconds before any caffeine was seen present in the brew.

Is the incidence of fungal diseases on Arabica coffee in it’s native range related to genetic variation in coffee?

Beyene Zewdie Hailu (Deparment of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden)

Looking at Ethiopian landraces, Hailu noted that there was no correlation between fungal resistance and inherent genetic diversity. However, there there is an inverse correlation between the frequency of fungal occurrence and genetic diversity.

This might imply — to my mind — that it is the diversity of coffee plant types in a given area, rather than the specific genetic code, that can help reduce the spread of fungal diseases like leaf rust or CBD.

Sensory profiles of cold, ambient, and hot full immersion coffee brews

Mackenzie Batali (Food Science and Technology, University of California, Davis, Davis, CA, United States)

Batali, mid-pandemic, carried out remote sensory testing for a hot, room temperature and refrigerated extraction of multiple roasts of multiple coffees. (It should be noted that all coffee was tasted by panelists the day after brewing, refrigerated)

She observed that under these conditions:

• “across all roasts and origins, floral flavor decreases with increasing brew temperature”
• “rubber flavor, bitter taste, and sour taste increase in hot brew coffee”
• Batali noted that the pH measured was higher (i.e., indicating lower acidity) in cold brew; however, the titratable acidity measured higher. She suggested that the next step would be to undertake mass spectroscopy to observe specific acids present in the various brew types.

Personal note: I would highly suspect that if hot coffee were tasted immediately after it was brewed, as is usually intended, the results here would be very different. However, if the goal is to produce cold coffee, this methodology may provide interesting insights as to how to roast and brew for specific flavor profiles.

Coffee postharvest – a crucial processing step for maintaining green coffee quality – or even more?

Dr Gerhard Bytof (Senior Manager Coffee & Science – Tchibo GmbH. Coffee Technology, Science and Research, Hamburg, Germany

Dr. Bytof reinforced Lonzarich’s notes on fermentation, defining “over-fermentation” as an “attack on the bean” rather than just the fruit surrounding it.

Bytof largely focused on coffee seed viability as an indicator of quality, offering these notes:

• The coffee fruit contains germination inhibitors, and pulping the fruit removes this, so germination markers in pulped coffees are observable on the first day of drying post-fermentation.
• By contrast, fruit-dried naturals don’t begin germination until 5-7 days of drying.
• However, drying coffee also induces “stress” metabolism that stops germination.
• Fewer of these “stress” inhibitors were observed in washed coffees.
• The specific germination amino acid precursor is present in such low concentrations that it is not observable to the senses, especially after Maillard reactions during roasting.
• Bytof noted that “aseptic” (that is, microbe-free coffee) has not been sufficiently studied, so the role of microbes during fermentation and drying — as they impact germination — are not fully understood.

It was suggested that:

• Quality loss might be correlated with seed viability loss.
• This may be related to the hulling timeframe; longer delays between drying and hulling increase viability, as parchment seems to better preserve viable seeds.

Coffee and climate change: the wealthy will win, the poor will lose, and coffee will survive

Dr. Piet Van Asten (Agronomy Head. Coffee plantations – OLAM International, Kampala, Uganda)

Dr. Van Asten noted that it’s important to understand the role of economics on leaf rust and other coffee farming issues: Yes, rust is terrible, but major outbreaks often follow “declined input use by smallholders” who are “demotivated by low prices.”

In other words, when a producer can’t afford fertilizers and pesticides or other management techniques like new hybrid varieties, the crop inevitably suffers substantially.

Yield decline in terms of climate change was observed to be more important for maximum nighttime temperatures rather than daytime, with the figure 16°C observed as the tipping point for yield decline.

Dr. Van Asten was the first of many researchers to note that in high carbon-dioxide environment (with enough water supply) coffee responds better than most plants, and does not self-regulate CO2 uptake by stomata closing (which would otherwise increase the leaf temperature adversely).

The implication is that drought stress may be mitigated because coffee is surprisingly well adapted to the greenhouse effect of higher CO2 levels under hot conditions

In sobering news, Dr. Van Asten observed that if/when global temperatures rise by 2°C:

• • El Salvador, Mexico, Tanzania, Kenya, and Guatemala would all exceed the vapor pressure deficit (drought) threshold.
  • Costa Rica, Brazil, Colombia, and Nicaragua would be spared this fate.
  • A comparison of the income and GDP of these countries indicates that the most financially vulnerable farmers are also the most susceptible to losses due to climate change.

Sustainability projects – sustaining old governance structures?

Aske Skovmand Bosselmann (Department of Food and Resource Economics, University of Copenhagen, Frederiksberg C, Denmark)

Bosselmann suggested that certification schemes, designed to improve or indicate sustainability, are likely only reinforcing preexisting power imbalances in the supply chain. This may not come as a shock, but it was refreshing to hear from academic researchers, who usually focus on the net-positive these certifications can indicate for macro-farmed coffee.

The Tanzanian smallholder coffee growers investment decisions in coffee production

Leonard Kiwelu (Special Project Unit, Tanzania Coffee Research Institution (TaCRI), Moshi, Kilimanjaro, Moshi, Tanzania)

Kiwelu reinforced Dr. Van Asten’s assertion that when coffee farmers are able to pay for it, they invest in their farms by planting improved seedlings. When coffee prices are down, these management techniques are abandoned.

Learnings of 15 years of coffee Cup of Excellence competition in 15 countries: Specific insight on the importance of varieties

Dr. Christophe Montagnon (RD2 Vision, Valflaunes, France)

Montagnon compiled COE data in a multi-year, multi-origin study, and concluded that:

• Over all countries, elevation was not a factor, but country-by-country it is.
• Gesha and pacamara virtually guarantee +1-2 point score.
• 0.5 point increase using yellow cultivars
• No statistical difference between traditional varieties & introgressed (hybrids)

Stenophylla coffee (Coffea stenophylla): the forgotten coffee crop species of West Africa

Aaron Davis (Natural Capital & Plant Health, Royal Botanic Gardens, Kew, Richmond, Surrey, UK)

While lower yielding, the West African indigenous coffee species Stenophylla — with its unique blackish/dark purple fruits — is markedly similar in sensory quality to arabica.

It presents an attractive alternative in light of climate change, as it has the best compatibility with a wide precipitation spectrum, may be grown at elevations as low as 400 meters above sea level and withstands higher temperatures and drought better than even robusta.

Evaluation of F1 hybrid (C. arabica L.) performances and farmer acceptance on-farm conditions in three producing regions in Ecuador

Juan Carlos Herrera (Plant Science Research Unit, Nestlé Research, Tours, France)

Herrera made a wonderfully simple observation based on studies in Ecuador that farmer opinion of acceptability and preference should be taken into account when developing and promoting new coffee hybrid varieties.