1. What is memory?

Memory is the process through which we obtain, store, retain and access information. Human beings are capable of perceiving reality through experiences, which we classify and store. This process allow us to survive, cause if we were not able to access past experiences to decode the new ones, we would be living each day in a constant chaotic state of wonder, terror, happiness or stress. Memory in simple words, simplifies our life and balances our central nervous system.

There are three types of memory, according to professors Atkinson and Shiffrin (1968, Multi Model of Human Memory) these are:

- Sensory Memory
- Short Term Memory
- Long Term Memory

Sensory memory is the very first stage and refers to the process of storage of information that we take with our senses from the environment. Unfortunately, most of it can't be processed by our brains, since it lasts for very short periods of time and just a small portion of it is transferred to the second and third stages of memory, short and long term respectively, the rest is quickly forgotten.

Humans are visual creatures, through evolution, this is the sense that we have developed the most. In fact, 90% of the information that we pass to our brain is visual. Perhaps this is the main reason why developing sensory memory through taste and smell is such a difficult task that requires a lot of training and hard work, and even many people are not physiologically capable of achieving it, since they do not have the appropriate sensory receptors to make use of it.
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2. We are all the same, but different.

Each human being is unique and unmatched. The composition of our bodies is such that there will never be anyone exactly the same. Although we all have a brain, a heart and two lungs, etc; brains have different capacities, there are healthier hearts than others, and lungs have different sizes, among other differences. In addition to our bodies, the composition of our life experiences is also unique, although we all live more or less the same script (we are born, we grow, we age and then we die), it is in the detail where the difference is found and what transforms us into unique beings.

For evolutionary reasons, our senses of taste and smell have been relegated to a second place. The dominance of vision has caused us to lose the ability to perceive and communicate taste and olfactory sensations. Humans in average have 12 million olfactory receptors, which can detect 10,000 different smells. But we don't all have the same number of receptors, nor do they have the same sensitivity. There are people who can perceive more aromas and flavours than others, and therefore, have a greater potential to communicate and memorize (retain, store and later access) this information or sensations.

In addition to our physiological limitations, our experiences are not the same either. We all live unique lives with experiences that are non-transferable. This is another fundamental aspect in the development of sensory memory. The environment where we live and its culture play a determining role in the way we see the world and what we can absorb from it. Then it’s only through language that we are able to share our experiences and express our emotions.

The environment is the stage, culture is the plot, our senses are the actors and language is the script, of this movie called sensory memory.
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3. The Flavour of Coffee

As we have already seen in previous posts, memory is a process that allows us to obtain, process, store and access information collected from our environment. And we also know that the possibility of access and communication of such information will be determined by a physiological factor (the unique composition of our bodies) and a cultural factor (the unique composition of our lives).

When we drink coffee, we have what is known as a multisensory experience. A cup of coffee contains a wide range of flavours and aromas, which are affected by many factors such as: the variety of the bean, process, roast profile, method of preparation, etc. Approximately 850 volatile compounds associated with coffee flavour have been identified. However, a small proportion of these (approximately 40 volatile compounds) are known to be the main contributors to the aroma and flavour of coffee.

Aroma is defined as an odour that is detected through the nose and retronasal, and also through the back of the mouth, where the nasal and oral cavities are interconnected. Taste is the sense experienced by the tongue and describes sensations of salinity, sweetness, acidity, bitterness or umami. Flavour is defined as a combination of aroma and taste.

This multi-sensory experience encompasses all the senses to provide the complete coffee experience and allows you to judge the quality and pleasure of the coffee. Drinking a cup of coffee without one of the sensory signals (for example, without feeling the aroma of coffee) will reduce the impact of the other senses, the overall experience and the pleasure derived from a good cup of coffee.
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1.- Origins of fermentation.
 
Fermentation is older than any ancient civilization that we know of today. Several archaeological excavations have found jars with the remains of wine that are approximately 8,000 years old.
 
After much trial, error and careful observation, almost all civilizations began producing fermented beverages (and foods as well), but mainly wine and beer. It started with the fermentation of water with honey in Asia, then the Egyptians, Babylonians and Romans used grapes to produce wine, the Chinese used rice instead to produce wine and other civilizations produced beer with barley. Chicha was produced in South America, through the fermentation of corn.
 
In those days people started to leave fruits and grains in closed containers, because they knew that after a long time, that would turn into wine or beer. But no one really understood how the recipe worked. The process was called fermentation, which comes from the Latin "Fervere" which means "To Boil". The name was created because after a time of leaving the fruit in the vessels, people saw the mixture bubbling, so they thought it was boiling.
 
Producing fermented beverages at the time was complicated, if the mixture didn't stay long enough in the container, the result would not have alcohol at all; but if you left it too long, it was undrinkable. After much observation, people understood that temperature and air exposure were critical to the fermentation process.

​2.- What is fermentation.
 
First of all, we must say that the general definitions of fermentation do not apply directly to coffee. This is because coffee is not a fermented beverage like wine or beer, but coffee production processes USE FERMENTATION AS A TOOL, either to break the mucilage structure and facilitate the execution of a certain processing method (Washed, Giling Basah, etc) and/or directly influence the quality and flavor of the bean (Natural, Honey, Washed, Giling Basah, Experimental, etc). Almost all the different coffee processing methods in the world use fermentation in one way or another, with the sole exception of mechanical washing.
 
So now that we've made this exception regarding to coffee, let's go back to the more general concepts of fermentation. In very simple words, fermentation is a TRANSFORMATION of a complex element into another much simpler one. OK, that's perhaps too simplistic! :)
 
Now more in depth: fermentation is a metabolic process that converts sugars into acids, gases or alcohol.
 
Louis Pasteur, the father of microbiology, who is responsible for all our understanding of fermentation today, pointed out in 1856 that there are two types of fermentation: Alcoholic and Lactic Acid. Alcoholic fermentation occurs through the action of yeast, lactic fermentation occurs through the action of bacteria.

3.- Coffee Fermentation.
 
As we already know, fermentation is a metabolic process of transformation of simple sugars into acids or alcohol. This can be divided into two main groups: alcoholic fermentation (produced by the effect of yeast) and lactic acid (produced by the effect of bacteria). But the variety of microbiota (that is, yeast + bacteria) that are involved in the fermentation process of coffee, is still poorly understood from a scientific point of view.
 
A study that we could find on "Mucilage Fermentation" from 2004 in Nicaragua (SC Jackels. Dept. of Chemistry, Seattle Univ.), Took samples from 7 different lots that were fermented in concrete tanks for periods between 10 to 24 hrs at a temperature of between 21 - 23 ºC; and concluded that: (1) in all samples the glucose level decreased constantly throughout the entire process; (2) that the levels of lactic acid and / or ethanol increased exponentially only in the last 3 hours of the fermentation process; (3) and perhaps the most important discovery, the PH level is a fundamental factor in determining when the fermentation would be complete, without developing unpleasant over fermented flavours (produced by acetic acid and ethanol), and this value on average was PH = 4,6.
 
The coffee microbiota has spread throughout the world along with its plants through human activity (Current Biology 26, 965–971, April 4, 2016). But also, the more "artisan" styles of coffee fermentation have generated several microbiota strains with independent origins. In other words, the bacteria and yeast found in Africa are different from those in South America, and these are different from those in Asia. These could play a much more important role in the development of unique cup profiles for different origins of the world, or what would be known as the "MICROBIOTIC TERROIR".

​4.- Types of Fermentation.
 
With this post we end this series of four articles where we have tried to understand fermentation in depth. First through its history, then understanding what exactly is fermentation, following on how it is used in coffee production; and finally we will see in detail the types of fermentation that are currently used around the world of specialty coffee.
 
We must say that the following types of fermentation, in the industry are called "experimental processes", and refer EXCLUSIVELY TO THE ENVIRONMENT where the coffee is fermented, and not to the metabolic process of fermentation, which by definition is anaerobic, meaning, free of oxygen.
 
AEROBIC FERMENTATION: Implies that the fermentation stage is carried out in an environment high in oxygen. It is the most widely form of fermentation used in coffee; and it occurs during the FW process when we dry-ferment (without water) coffee in a tank, or when we dry natural or honey processed coffee on African beds or concrete patios.
 
ANAEROBIC FERMENTATION: Implies that the fermentation stage is carried out in a low or no oxygen environment. An example, take place during the FW process when we wet ferment (soak) coffee in a tank with water.
 
LACTIC FERMENTATION: Generally is carried out in a steel tank in an anaerobic environment. After pulping, it's assumed that only the especies of bacteria which transform  glucose into lactic acid are alive. There is little scientific support to this, since there are other microorganisms (like yeast) that can also survive in low oxygen environments and could also influence the final result of this type of fermentation.
 
CARBONIC MACERATION: Process borrowed from the French wine industry, and made popular by Sasa Sestic WBC 2015. The process is similar to that described above, but fermentation is done with the whole cherry without pulping. Fermentation here may take days or even weeks since the cherries are left intact.
 
YEAST FERMENTATION: As we have said, yeast and bacteria are microorganisms present in the soil, water, air, tank, pulp, etc. But this process refers exclusively to the adhesion of commercial yeast strains (generally the one used in the wine industry) to the tank, where a wet anaerobic fermentation is being carried out.
 
To wrapped out, we just want to say that all these experiments are great, because this industry has been built and grow on experimentation; but not because a process has a "funky" or "trendy" name it will be better than another which is simply called "washed" or "natural". Let's select our coffees by their cup profile and not by their names.
 
Honorable mention to many people from whom we borrow info (all references on our blog), and especially to Lucia Solis from the "Making Coffee" podcast.
 
THE END

​The taste of people has been built with the course of history, and some events have strongly contributed to shape it. Like for example, the arrival in Europe of sugar or spices during the medieval era. Throughout history some flavors appears and others, like bitterness, go out of fashion.

​Taste today, is strongly influenced by current times. In a connected, interdependent and frenetic world, we depend on our socio-historical condition to appreciate the flavor. 

Aroma, taste and flavor are closely related concepts, however, they have different definitions. Taste and aroma are closely associated with each other, and both are perceived by processes within the areas of the limbic system, which deal with emotions, memories and stimulation.

The aroma is defined as an odor, perceived through the nose and retronasally, and also through the back of the mouth, where the nasal and buccal cavities are interconnected. Taste is the sense experienced by the tongue and describes sensations of saltiness, sweetness, acidity, bitterness or umami. Flavor is defined as a combination of aroma and flavor.