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coffee Fermentation

Saeed Abdinasab — Sun, 10 Nov 2019 08:15:13 +0000

general

Wet processing of coffee often includes a fermentation step, cocoa always does and tea processing has a step that is sometimes called ‘fermentation’. In food production there are many fermentations that confer nutritional, taste, stability or all of these benefits on raw materials. Sauerkraut, yoghurt, salami, tempe, uji, soya sauce, beer, and cheese are a few examples of scores of food fermentations known around the world.

Coffee fermentation, as we will see, is conducted for rather different reasons. The term ‘fermentation’ represents microbial growth as it occurs on any suitable substrate. In fact, in the early days of microbiology, the organisms that grew to spoil food were originally called ‘ferments’, rather than ‘microorganisms’, hence their growth was termed ‘fermentation’.

A second, narrower sense of ‘fermentation’ is often used in microbiology, which we will not use in this discussion: microbial activity in the absence, or near absence, of oxygen. However, it is worth remembering that vigorous microbial metabolism often depletes oxygen (and so augments CO2) thus oxygen limitation is usually an important aspect of food fermentations. It is an important factor in the selection of a fermentation community from the initial community of microorganisms. Bacteriologists also speak of fermentative organisms – microbes that do not require oxygen for respiration and oxidative species that do require oxygen for growth. In referring to organisms, we will use these bacteriological terms.

The so-called fermentation of tea raises an important aspect of some food fermentations. The changes wrought in tea by ‘cutting, tearing, curling’ (CTC), followed by aeration are produced by plant enzymes, not microbial activity. There is often a potential ambiguity in the roles of microbial and plant metabolism in processing systems since often both kinds of organisms are simultaneously active at some time during the process. Cocoa fermentation is required for flavour development although it also aids separation of seed from fruit tissue. Coffee fermentation, though it may have an impact on flavour development, is not required for flavour development and is conducted essentially to aid a similar separation of tissues.

Microorganisms occur naturally on and in the coffee fruit in increasingly large numbers as the fruit matures. The seeds themselves become active with maturity and a proportion of seeds will have undergone the early changes associated with germination by the stage of full ripeness. The fruit itself has no capacity to store, unlike apples and oranges, for example. Resident micro-organisms become active soon after harvest and signs of (unintended) fermentation can be measured soon after harvest. The object of our discussion here is principally the scheduled fermentation used to degrade the mucilaginous mesocarp tissue of the fruit.

Structure of the Coffee Fruit

The product of coffee are the seeds which are produced in small cherry-like fruits, normally in pairs. Of particular significance in understanding coffee processing are the three tissues of the fruit: the epidermis (or skin); the mesocarp (or mucilage) and the inner integument (or parch).

The epidermis is typical of plants, comprising a layer of small cells, including stomata, their cell walls impregnated with suberin, a water impermeable wax. Beneath this is the mesocarp which consists of many layers of parenchymatous cells – undifferentiated thin walled cells and which, in the ripe fruit, are large with large vacuoles. The inner integument, which is tightly adpressed to the seeds, is a very tough and relatively inelastic layer no more than two or three cells thick but comprising cells with considerable secondary thickening, i.e. it is essentially woody. Xylem tissue, presumably once connected to the funiculus (the tissue that connects the seed to its nutritional supply during development), can be easily seen in the integument by direct observation, running parallel to the surface of the tissue.

Before ripeness, the skin, mesocarp and parch form a tough and tightly adpressed covering to the seeds which are relatively soft at this stage. Attempts to remove the seeds at this point will invariably break the seeds. When ripeness is reached, the mesocarp becomes soft (hence the term mucilage), and the seeds relatively hard. If mechanical shear is applied now, the mesocarp splits to produce one fraction of skins with some mucilage and a second fraction of seeds tightly covered in their integument (parch), which is covered in a fairly thick layer of mucilage. this second fraction that is fermented to enable removal of the mucilage from the seeds.

It can be that the mesocarp of robusta fruit is thinner than that of arabica. It is, however, tougher and more difficult to remove from the parch. The mesocarp adhering to the parch is chemically quite different to that adhering to the skin. It lacks the characteristic anti-nutritional compounds such as tannins, free phenolics, caffeine and other alkaloids that make skins refractile even in composting. A tonne of ripe arabica cherry yields about 120kg of mucilage adhering to the beans. About half of the 17kg of the dry mass of this mucilage is sugars or some 8.5kg of sugars. This is the source of fermentable carbohydrate for the coffee fermentation. There are also minerals, particularly Ca, K and P, and amino acids present.

Pectic substances amount to about 35% of the dry mass of the bean-associated mucilage. They comprise essentially polygalacturonic acid chains (covalent bonds typical of all polysaccharides) that are cross-linked, via Ca+2 ions through the carboxylic groups of the uronic acids. As will be discussed below, the esther part of the carboxylic group and the glycosidic bonds of the chains are susceptible to attack from enzymes.

Wet Processing and Dry Processing:

Coffee must be dried in order to stabilise it and preserve quality. Wet processing refers to various methods where the seeds are mechanically separated from the skin of the fresh fruit (pulping) before drying and may or may not include a fermentation step. Dry processing refers to methods where the fruit is either dried directly or is disrupted, but the seeds not separated from the fruit tissues, then immediately dried. The decision as to which method to employ is based on economic considerations. Washed coffee commands a higher price, but is more expensive to produce.

A large proportion of arabica coffee is processed by the ‘wet method’ and a high proportion of this has a fermentation step in it. The market for washed robusta is limited, and the premium offered above dry processed robusta is small. Therefore, only a small proportion of robusta coffee is processed by the wet method, the bulk of this in India.

Capital costs for wet processing are high. Power, provided by mains electricity, petroleum powered generator or direct drive arrangements is required for even moderate sized operations. A good water source and fairly well-designed plumbing is also required. A facility to house equipment and various sealed channels and tanks are also necessary. The equipment comprises a pulper as a minimum, and typically includes a hopper, siphon tank, post pulping screen, washer or washing channels and skin-drying screens.

Operational costs are also higher for wet processing. Harvesting is particularly expensive because it requires the very labour-intensive selective harvesting system – only ripe cherries can be pulped. This is beginning to change due to new equipment that can accept (but not pulp) immature cherries. Further costs accrue because cherries affected by coffee berry disease, immature or over ripe cherries must be separated and sold as low grades, returning a low price.

There are generic differences in taste attributes between washed and natural coffees and both are required for different market segments: wet processed coffee yields a ‘softer’ cup with less body and higher acidity while the ‘arabica naturals’ excel in their body and bitterness while lacking acidity. Within the classification of washed coffees there are two commercial market segments: ‘Colombian milds’ and ‘other milds’, a distinction that is delimited by origin. Either may or may not be fermented and the ‘other milds’ characteristically have more body and less acidity than ‘Colombian milds’.

Coffee Fermentation:

Coffee is fermented, as mentioned above, to ease the removal of a layer of mucilage from the seed/inner integument to which it adheres. This is not to say there are no taste implications to this step. In contrast to coffee, the fermentation of cocoa is required to develop the flavour of the product though much of this is apparently accomplished by cocoa enzymes, rather than microbial activity. In coffee too, it has long been held that fermentation has a beneficial effect on flavour but lately, this has been disputed and many quality experts now accept the contention that mechanically washed coffee (with no fermentation) can be of comparable quality to the fermented product. What is beyond dispute is that badly conducted fermentation can result in disastrous losses in quality.

In general coffee fermentation is conducted as ‘dry fermentation’ where the mass of mucilage and parchments are not covered with water. The temperature of either of these processes is scarcely raised above ambient temperature reflecting the lack of oxygen diffusion to the heart of the mass. In contrast, fresh cherries held in woven sacks, an arrangement that has about 50% space, can heat to over 50OC within 36h. From a taste quality point of view, the fermentation step and operations either side of it (pulping and washing) are said to require conformance to certain criteria.

Firstly, the fermentation mass must comprise uniformly parchment coffee with a minimum of crushed or naked beans, skins and un-pulped coffee. Crushed and naked beans indicate beans with severe insect damage and/or a pulping machine being set too narrow. Presence of skins suggest the pulping machine is in need of maintenance and/or the water feed was too low. Un-pulped beans suggest that the pulper was set too wide and/or the removal of dried fruits has been ineffective.

Secondly, the fermentation must be concluded as soon as possible after sufficient mucilage degradation has been accomplished. This is ascertained by rubbing the parchment between your fingers to note whether the grittiness of the parchment surface can yet be felt.

Thirdly, after washing, mucilage must be completely removed from the parch before drying. Curiously, a product called descascado, produced with no attempt to remove mucilage, being pulped and immediately dried, can be a coffee of the highest quality.

The most important of these conditions is the temperature and the length of the fermentation. As mentioned above, coffee fermentation is not significantly self- heating so prevailing climatic conditions control temperature. The period of fermentation, in practice, can only be concluded when it is possible to take the coffee to the next two steps: washing and either soaking or drying. This normally occurs first thing in the morning since the afternoon and evening is reserved for pulping operations. Given that pulping always takes place in the late afternoon through the evening and requires everyone’s attention, fermentation periods will tend to be about 18h, 40h or 64h. Robusta usually requires at least one day more than arabica.

Microbiological aspects:

The outcome of a process like fermentation is a consequence of what goes in and what conditions are experienced during the fermentation. We have seen that there is about 8.5 kg of sugar in the pulp of 568kg of pulped coffee and another 6kg of pectic substances. The balance of the 17kg of dry matter is ash, amino acids, cellulose and so forth. Most of the organisms are provided by the mucilage community with some from the processing water and incidental skins, etc.

However, the conditions, as they develop, provide exceptionally powerful selective pressure toward fermentative organisms that can thrive at low pH. The fresh mucilage has a pH of about 6.5. This falls rapidly to a minimum of about 4.1 to 4.3. Although data is lacking, it is clear that oxygen tension falls with the fall in pH, both concomitant with growth. Typical of food fermentations, the ‘wild’ microbial flora of the raw material changes quickly and completely to species that were present, but rare, in the fruit-inhabiting community.

Studies of ‘wild’ fermentations are very arduous to conduct because of the sheer numbers of organisms and taxa and the difficulties in accurate enumeration and identification of them. The nomenclatural problems of synonymy and teloemorph/anamorph names make comparing different studies difficult. New methods based on DNA PCR amplification and gel electrophoresis which allows direct analysis of the fermentation liquor without an isolation step, may provide a means to solve these severe practical problems in future.

In general, the fermentation can be characterized as a mixed yeast/bacterial fermentation. Kloekera apiculata (=Hansenispore apiculata = Saccharomyces apiculatus) and Hansenispore uvarum are reported to dominate the yeast population with other yeasts such as Pichia kluyveri (=P. fermentans) and Kluyveromyces marxianus (=Candida kefir = C. bulgericus). The yeast species are fermentative and the dominant species share the characteristic of only assimilating and fermenting glucose amongst the usual sugars tested to identify yeasts.

The bacterial side of the fermentation is conducted by lactic acid bacteria, some Enterobacteriaceae and Bacillus. The most common bacteria to produce pectolytic enzymes are Pseudomonas (P. fluorescens, for example) and Erwinia (E. carotovora, for example). Of these only Erwinia is fermentative and, in fact, the presence of Pseudomonas is difficult to demonstrate in fermentation liquors. In general, the lactic acid bacteria have been reported to be more numerous than the Enterobacteriaceae.

Analysis of several fermentations under the project “Enhancement of Coffee Quality Through the Prevention of Mould Formation” has shown that the balance between yeasts and bacteria can vary widely, such that some are primarily bacterial and others dominated by yeast. It is not clear how the outcomes of these two types differ, or why it should differ.

The conditions of low oxygen tension and high water activity dictates that the oxidative, mesophilic species of Aspergillus capable of OTA production will not thrive during fermentation. In laboratory studies, large numbers of spores, introduced into the fermentation mass at the beginning of fermentation did not result in any OTA appearing in the beans and the organism (A. ochraceus) could not be recovered from the beans after drying.

this test is only valid for models where spores, let us say from the fruit skins or soil contamination, are the source of the OTA producer. In fact, a proportion of beans harbour these fungi, infected before harvest, and there is some evidence to suggest that fermentation can kill them in the beans. However it is clear that fermentation does not always do so. In other tests where pulping was delayed for up to six days after harvest, the protective effect of fermentation against OTA accumulation was not observed. This could be interpreted as there being some threshold biomass above which the mesophilic fungi can survive the fermentation well.

The presence of skins with the parchment is unlikely to affect the fermentation course with respect to OTA production. The presence of dry cherries, which go through the pulper due to their small size, present a different scenario. If we assume a greater development of OTA-producers could have occurred under the extended period of oxidative and mesohydric conditions of this material, the fermentation would not protect and significant OTA production could occur if not during the fermentation, then later during drying.

There are three classes of Pectolytic enzymes. Plants and fungi produce pectin esterases which remove methoxy groups of the uronic acids revealing carboxylic groups through which Ca+2 coordinates the chains. Certain fungi also can produce Pectin lyase, an enzyme that attacks the 1,4 glycosidic links of fully esterified (methoxylated) chains. Lastly, Polygalacturonase is produced by certain bacteria and it also attacks the glycosidic links but only of partially de-esterified chains or segments. The oxidative yeast Cryptococcus is common in the fruit and it is reported to be pectolytic but numerous isolates from coffee have been checked without a positive result. A few Candida species are also reported to liquefy Ca- pectate.

The role of microorganisms in taste defects of wet processed coffee is a matter of debate. Of the numerous defects often attributed to problems during fermentation, the three most serious are ‘fermented taste’, ‘sour’ and stinkers. But because fermentation can occur in the intact fruit, especially if harvested and not processed expeditiously, the same defects can arise in natural coffee and, by extension, in wet processed coffee where the fault was actually elsewhere than the fermentation step.

A fermented taste has fruity aldehyde tones; sour is likened to onion; stinker is a powerful foul taste, and a single stinker bean can effect several kilograms of product. Stinker beans have been attributed to the growth of Bacillus brevis or high levels of lactic acid bacteria and maybe fairly specifically associated with derivatives of methyl-butanoic acid, cyclohexanoic acid esters and S-containing organic compounds. Some compounds that can be traced to a defect also indicate the source where few organisms produce the compound. Earthy and mouldy odour can be attributed principally to 2-methyl-isoborneol and geosmin, respectively. These compounds are produced notably by species of Eurotium, a few other moulds and some actinomycetes.

Soaking:

In some processing chains, whether or not fermentation has been conducted, a soaking step is sometimes applied. This is sometimes called secondary fermentation where a fermentation step is included in the process or fermentation where mechanical mucilage removal has been used. After mucilage removal the parchments are held under water for a period from overnight up to, rarely, 48h. The principle effect is to cause the beans to become more uniformly dark blue- green, a desirable physical character that itself has no taste implication. The colour is the same as that generated by the hydrated bean in response to physical injury, say damage by a coffee berry borer or cutting with a scalpel. The colour is likely to be a hydrolysis reaction akin to the chlorogenic acid reaction – it is not chlorophyll production.

Some authorities claim that soaking removes or reduces any harsh ‘edge’ the cup may have but, if true, it is unclear whether this is due to leaching (some slight leaching has been reported), or the metabolism of the seeds in essentially anoxic conditions. For coffee without this ‘edge’ there is no change in cup quality for up to 7 days, according to one study. The harshness is usually attributed to phenolic compounds so the implication would be that, through one mechanism or another, certain phenolic compounds are removed or altered.

After washing of the parchments, considerable yeast and bacteria remain on the surface and, with the yeasts, even in the bean tissue. However, there is very little substrate for microbial growth so metabolically, this period under water, is quiescent. Short periods of soaking do not seem to be associated with flavour defects outside of the use of tainted water for the soaking.

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What affects coffee during roasting

Saeed Abdinasab — Tue, 23 Jul 2019 22:19:40 +0000

What affects coffee during roasting

Controlling variables during roasting process

Coffee roasting includes adjusting many variables to create your perfect roast profile. By changing factors including temperature, length of roast, and airflow, you can highlight sweetness, emphasize acidity, or create a well-balanced roast. also drum speed, you can affect the amount of time that coffee beans are exposed to direct heat.Now you can change all those variable, Should you roast a Colombian Nariño the same way you would an Ethiopian Sidamo? Probably not.Producing countries have different climates, soil types, altitudes, density, moisture, – and all that leads to very different coffees. The beans will react differently to heat, plus you will want to accentuate specific characteristics. In other words, you need to roast them differently.So before you create a profile and put your coffee in the roaster, you need as much information as possible about the beans. And today, I’m going to take you through some of the main origin-based variables to consider. At each stage of the coffee supply chain, the moisture content of a green bean must diminish – or the bean might become moldy, defective, and less valuable than before. Ensuring a bean dries correctly is essential in order to optimize its quality potential and minimize the chance of problems.Roasters, near the end of the supply chain, have two tasks when it comes to managing moisture content. On the one hand, they must maintain the lots they store onsite within a narrow moisture range that is acceptable to their quality standards.

On the other hand, and in the span of a few minutes, the roaster is responsible for driving the last remaining bits of moisture out of the bean via the application of intense heat and pressure. In these minutes, the coffee is exposed to the most energy it will experience at any point in the coffee supply chain and the roast is set up for either success or failure.It’s easy to see why roasters should care about the moisture content of their coffee. But how useful is a number supplied by an importer, and how can roasters integrate moisture content readings into their craft? I spoke with Fred Seeber of Shore Measuring Systems, a supplier of moisture content meters, about measuring and making sense of moisture content in green coffee.

There is no official standard for ideal moisture content in green coffee, although the ICO recommends 11% as a good target. However, it’s commonly accepted that 10-12% is a reasonable range. Anything less than 10% is likely to result in loss of cup quality, while humidity at higher levels begins to create a risk of mold growth. Yet a coffee’s humidity is not static. While the pre-export drying process drastically increases a bean’s stability, changes in moisture content are still possible. Environmental factors, such as being in a particularly humid or hot location, are a common cause of this. Before getting into the technical details of measuring moisture content, it’s worth digging a little deeper into why it’s worth measuring moisture content. Knowing this will help you establish protocols suited to your specific needs.

For roasters of a certain scale, it’s simple: you pay for coffee by weight; the more water in that coffee, the more you’ve paid for water which you’re going to burn off anyway. common situation roasters find themselves in: “So, [an importer] sends you a sample, and… it’s showing 11.5% moisture in that sample. Then when your container shows up, that’s 40,000 pounds, and all of the sudden you discover it could be 13% moisture. Well, you just got blanked for two percentage points of water of a commodity that’s four bucks a pound… that’s [a lot] of money.” For the smaller, quality-focused roaster, those kinds of calculations may or may not be relevant. But moisture content still plays an indirect role in a roaster’s costs, regardless of whether or not they’re buying a few containers or a few bags.

There is no direct link between a coffee’s quality and its moisture content. A 10% humidity coffee is not necessarily better or worse than a 12% coffee. However, over time, green coffee will gradually lose vibrance. This will eventually result in the dreaded “past crop” flavor, and this process is associated with the drying out of the coffee. Therefore, even for a small roaster, it’s important to keep track of moisture content. If you paid for an 85-point coffee at 12% moisture, by the time it reaches 10% moisture it may be more like an 83-point coffee. Yet, you still paid 85-point prices for it originally.

By comparing moisture content loss with quality degradation over time, you can make smart buying and consumption decisions with your green lots. And, when combined with water activity measurements, you can even predict the shelf life of your green coffee. Again, precision here is key: you want to track your coffee through a narrow range of percentage points over a long time frame. Lastly, you may think to yourself that you don’t need to measure moisture content yourself, since your importer supplies those numbers already. Fred cautions against this thinking. He points out that coffee is shipped on water and that ports can often be warm and humid, which will affect moisture readings. So, if you’re a roaster in a dry part of the United States but your importer is located in New Orleans or Houston, and is taking moisture readings from lots right as they arrive, those numbers might not be applicable to you by the time your coffee arrives at your facility. Elevation, or altitude, is of immense importance for coffee roasting – but what we’re really talking about is density. When coffee is grown at cooler temperatures (which, most of the time, means higher elevation), the cherries ripen slower and so develop more sugars. This leads to more complex sweetness, but also to harder, denser beans. When you have beans of different densities, they also react differently to the heat. Soft, low-density beans tend to have more air pockets inside them, which can slow down heat transference. To avoid scorching the outsides of the beans, you should use a lower initial charge temperature. We also recommends extending the length of the roast for these coffees. Knowing what altitude your coffee is grown at, how far it is from the equator, and the temperature on the farm will help you to anticipate the density. When roasting, it’s important to consider not just the structure of the bean, but also the flavor of it. And this can vary greatly. “We will never have an Ethiopian with the same type of acidity like that Kenya AA Kamwangi we once had,” Tom tells me, “and it will be very difficult to find a Colombia with the stone fruit, tea-like flavors of the Yirgacheffe coffees.”

you can expect well-balanced coffees from the Americas, with more chocolate and hazelnut notes appearing in Brazil. In East Africa, coffees tend to be clean, juicy, and fruity. Some regions lean more towards sweetness (like Burundi), while others are more acidic (like Kenya). Indonesia is often known for its heavy body and earthy tones. Yet there are so many flavor variations within one region, as a result of micro climates, terroir, varieties, production and processing methods, and more. Sulawesi, Indonesia is famous for its spice notes, while Bali has a more citric profile. A Panamanian Geisha will taste different from a Panamanian Bourbon. Brazil is so large, you can fit much of Europe in it – and it has a wide variety of profiles to match. And as Tom points out, some countries have multiple harvest seasons. it’s the roaster’s job to preserve what makes an origin special and “let the coffee speak”. Knowing the profile of the coffee origin will help you anticipate which flavors will be most prominent – and how you can emphasize them. roast graph data into two types of curves: control curves and reading curves. Control curves are variables that you directly control during the roast, such as the heat settings, airflow, and gas flow. Reading curves are temperature readings. Since the variables are constantly changing, they are recorded as line graphs.

But what reading curves do you need to know? the key ones are bean temperature, air/environment temperature, and rate of rise curves – although you can also measure bean color, air, and gas pressure for even greater insights. Denser, higher-altitude coffees are associated with greater acidity, and you’ll often hear this described in terms of fruit notes – mandarin, grapefruit, plum, blueberry, and so on. This is a highly prized trait, and if you’re roasting a coffee that has this quality, you may want to accentuate it. (Bear in mind, however, that while acidity can be good, underdeveloped and sour notes are not. There is a fine line.) the more acidity and fruitiness you will throw away. A faster Rate of Rise (RoR) is also recommended by many roasters for emphasizing acidity. On the other hand, if you want more sweetness – say you have a natural Bourbon from Burundi – then Willem Boot, CEO of Boot Coffee, recommends opting for a lower RoR. Sweet Maria’s also experimented with stretching out the drying phase of the roast, and found that it could highlight this quality. as for body, stretching out first crack could open up a more syrupy mouthfeel in a coffee. It’s important to remember that the qualities you want to highlight will all depend on the coffee itself, and its unique, overall profile. Roasting is a complex skill; there are no simple rules. These guidelines are just starting points for creating your roast profiles. Knowing the altitude, temperature, terroir, and origin profile is a great start to creating a roast profile for a coffee. “It’s about a commitment to get to know the origin and bring the best to the surface,”

But it’s only a start.

Bean temperature(the blue line)

The bean temperature curve will look a bit like a check mark; once it starts going up (something called the turning point – more on that to come!) it should always continue going up. If not, you risk stalling your coffee and developing bread-like, doughy flavours

ROR(other blue line which is vice vers)

The rate of rise curve is linked to bean temperature, but there’s a subtle difference: it measures the rate at which bean temperature changes. This will give you far earlier indications of temperature changes and, in turn, allow you more control over the roast. It has a very different shape to the bean temperature curve, rising sharply from zero shortly after the turning point.

Air temperature(RED line)

Air temperature is variable measures the environment inside the drum. It’s useful to know because much of the heat transfer in coffee roasting is via air. This line will follow a similar shape to the bean temperature curve.

Key Stages on Your Roast Graph

Now we know what the roast graph measures, you can start reading and interpreting these lines. To do so, you want to pay attention to several key points on the graph: charge temp, turning point, first crack, and end temp.

Charge Temperature

This is the temperature of your drum just before you add the coffee. By manipulating this, you can speed up or slow down the rate of rise and, in turn, choose how much acidity to accentuate. You should also pay attention to bean density and processing method when selecting this.

Turning Point

As you add the cold beans to the roaster, the heat inside the machine will dramatically fall before starting to rise again. The point at which it begins to rise is called turning point.

First Crack

One of coffee roasting most famous moments is first crack. First crack signals that the beans are almost ready. As the beans expand and moisture evaporates, steam develops inside the beans. This steam then forms pressure that cracks the beans open.

First crack it’s a moment that has been given almost mythical status in coffee roasting – and it deserves it. A key stage in any roast, understanding it will give you insight into how flavors and aromas are developing.

End Temperature

As the name suggests, this is the temperature at the end of your roast.

By understanding what’s going on inside the roaster at these key points, you’ll be able to start evaluating the impact of them on your beans. For example, by manipulating charge temp you can speed up or slow down your roast. The duration of first crack can affect body. Roasting graphs may, at first, be challenging. There’s a lot of data to collect and understand. However, as you start to work with air temperature, rate of rise, first crack, and more, you will begin to gain real mastery over how your coffee beans develop during roasting. So don’t be intimidated by these charts – start recording those temperatures and see how it helps you as a roaster. As heat is applied to the coffee beans, they go through endothermic and exothermic reactions. Up until first crack, the beans absorb the heat (an endothermic reaction). The moisture dissipates and the color changes from green to yellow and then brown. The aroma will be cereal-like: think toast, popcorn, or grass. As for first crack, this is a brief exothermic reaction: the beans release heat (energy) in the form of that steam we mentioned above, along with carbon dioxide. The bean will have doubled in size and shed the majority of their silver skin, but oils won’t yet be present. After first crack, it switches back to an endothermic reaction until second crack, the final exothermic reaction (if you choose to roast your beans that far).

Flavor Development

Although we like to talk about first and second crack when roasting coffee, it’s important to remember that coffee flavor profiles are the real goal. And for this reason, we also need to consider caramelization and the Maillard reaction. Both of these happen before first crack. The Maillard reaction occurs when we start to see browning, and it creates many of the flavors in our coffee – especially the savory ones. As for caramelization, it happens a little after the Maillard reaction it as the dehydration of sugars through heating, which then give off the carbon dioxide and H2O that cause first crack. As you may have guessed, this process leads to caramel flavors in the roast – but it’s also what causes bitter notes if the heat continues for too long. It’s hard to predict exactly when these reactions will take place. Joe tells me that they occur as a result of the amino acids and sugar molecules, and as these break down, hundreds of reactions occur. These reactions start at different temperatures, but, due to different coffee structures hitting these different temperatures at different times in the drum, they can overlap. Since it’s so difficult to anticipate these reactions, it’s even more important to pay attention to the aroma and color of the beans.

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You need a barista

Saeed Abdinasab — Thu, 11 Jul 2019 11:56:20 +0000

You need a barista

Generally, a Barista will need a lots of practice, documents and learning objectives to gain required skills to achieve Training Certifications. In addition we will guide you through this article that shows you how you can improve yourself as a barista and how to evaluate your skills.

In a new effort to document and record the many learning objectives and skills required to complete your Training Certifications. We will post a series of articles about how you could improve yourself as a barista or how you can evaluate your skills or any other baristas at a glance.

Coffee Beans

The differences between Arabica and Robusta, including growing conditions, caffeine levels, pest & disease resistance, flavor, and visual differences. Recognize key differences between Arabica & Robusta is can be from their taste and shape, The importance of coffee freshness, including The use of a sealed bag, ideally within one month after roasting and within a maximum of three months; Grinding coffee fresh (to order) within 1 minutes of preparing; another topic is how much importance of using fresh coffee beans and how to keep them fresh, you need good storage of beans in the hopper overnight or when not in use; for roasted bean Keeping lids on the bean hopper and dozer chamber; Store beans far away from air, moisture, light, and heat; Maintaining a stable temperature for roasted lower than 18 degrees and for green bean 60% moisture and 21 degrees for temperature and should be stable.

Workspace management

Maintains a hygienic and organized workspace that minimizes waste demonstrates the appropriate position for commonly used tools, eg tamp, pitchers/jugs, clothes, etc. you need to design your work area and workflow line to manage it in the busy time.

Grinding, Dosing and Tamping

The importance of keeping the work space clean, tidy and organized at all times The correct terminology to Identify correctly all key identify parts of grinder (hopper, espresso machine and adjustment collar, dosing grinder component parts chamber, fork, on/off switch) and espresso machine including switches (steam wand & tip, portafilter handle, group head, dispersion screen & gasket, drip tray, gauges, hot water spout, on/off switch, continuous/AV buttons) The acceptable range (per definition) of coffee used in espresso, and how distribution of coffee grounds affects extraction. The impact of tamping on distribution, and extraction flow, it’s important to know demonstrates the basics of dosing, distribution and tamping and their impact on extraction is have a huge effect and has too many variables for making good espresso shot. The correct dosing action has an effect on achieving correct input with minimal waste. Demonstrates good dosing and distribution technique to keep dose consistent from one espresso to the next and to minimize channeling, Calibration of a grinder is the main part for choosing the tastes. The grinder should be calibrated to produce an espresso that falls within all standards. The grinder should be purged between adjustments, Demonstrates grind calibration, using a grinder with a dosing chamber OR an ‘on-demand’ grinder. How the grind affects shot times Identifies when a grind is incorrect and corrects it to produce espresso in 20-30 seconds. The correct use of a tamper to produce a flat and even surface on the tamped cake and to reduce repetitive strain injuries for a good tamping technique using a hand tamper

Extraction and Brewing

Espresso is a method of preparation that takes finely ground coffee, compacts it into a portafilter and forces hot water through it under pressure to make a concentrated coffee beverage , Sensory attributes are used to describe coffee, There may be regional variations to espresso and cappuccino parameters used in the traditional ways but normally I required just espresso with big basket as well as every one know with “double espresso basket”, there is no anymore single or double. just ESPRESSO : Dose depend of basket as you using, normally for specialty coffee it would be 18g – 20g or 21g , you should dose accurate size or 1+- for it. Brew ratio for espresso can be 1 / 1.5 , 1 / 2 or 1 / 2.5, mean for espresso 20 gr in and 40gr out is ½ which is standard and most of the time its work. Shot time: 20 – 30 seconds, you need analyze the key defining parameters of an espresso used within any examinations that you have , Tastes and describes attributes, such as aroma, body and flavor, of an espresso Chooses appropriate terms to describe flavor from the Specialty Coffee Taster’s Flavor Wheel

Try to understand how regional variations in parameters have effect on last flavor, There are five interdependent elements to brewing espresso: The bean / The barista / The machine / The grinder / The water , Lists of the five inter-dependent elements to brewing espresso which is in upside line , controlling them and know how they have effect on your last flavor is keep your consistency as well.

Preparation of the espresso machine requires:

Prepares the machine for use correctly and with appropriate equipment
Having separate cloths for steam wand, counter and portafilter
Checking that boiler pressure is up to 1 bar before use;
Warming (seasoning) group handles by pulling a minimum of 1 shot per group before dialing-in;
Stacking cups on cup warmer and saucers and spoons etc. next to the espresso machine
Preparation of espresso involves the following steps:
Remove portafilter from grouphead and flush group
Wipe basket clean and dry
Dose and distribute desired grams of coffee
Tamp consistently, level & ergonomically
Clean loose grounds from portafilter surfaces
Insert portafilter into the grouphead and start the pump immediately, as one continuous motion
Observe the flow and stop pump appropriately
Serve or use to make espresso-based drink
Remove portafilter and knockout spent grounds
Wipe basket clean and flush group (rinse optional)
Return portafilter to grouphead to keep preheated
Demonstrates the correct steps for preparing espresso according to SCA standards
Understanding of basic sensory qualities of
Under-extracted espresso (thin body, unbalanced flavor with high acidity, poor crema),
Over-extracted espresso (unbalanced flavor with high bitterness, poor crema)
An acceptable espresso (good body round and smooth, well balanced flavor (acidity, sweetness, bitterness), good visual crema which covers whole espresso (in line with coffee used)
Recognizes by sight and tastes the differences between under-extraction, over-extraction and acceptable extraction

Milk techniques

The importance of using fresh milk in maintaining foam standards:

Expired milk is unfit for consumption and should be discarded
The time milk is left out of the refrigerator should be minimized
Stock should be rotated (first in first out)
Pitchers/milk jugs should be emptied and cleaned before use
Pitchers/milk jugs should not be prefilled
Milk should not be re-steamed
Describes the measures required to maintain freshness of milk
Milk should be produced with consistently dense texture, with no visible bubbles and a shiny surface. (See SCA Foam Quality Guide).
Demonstrates the appropriate techniques required to produce correct milk texture (micro- foam).
There is a desirable range of milk temperature: 55c-65c (131- 149F) (Maximum temperature 70c/158F, Minimum of 50c/122F).
Demonstrates the appropriate techniques for producing the correct milk temperature
All temperatures are measured in the cup, not the pitcher/jug
The correct steps in foaming milk are:
Empty and clean pitcher before use
Purge steam wand before foaming
Wipe steam wand immediately after use
Purge steam wand after wiping
Minimize milk waste
Demonstrates hygienic and efficient steps when foaming milk
Drinks should be prepared to the required composition and visual requirements
Performs the techniques required to produce a cappuccino and caffe latte

Barista menu

An espresso should be served to the specified size, taste and visual parameters (as per SCA exam requirements).
Demonstrates good techniques for preparing and serving an espresso
A cappuccino should be served to the specified size, taste and visual parameters (as per SCA exam requirements).
Demonstrates good techniques for preparing and serving a cappuccino.

Hygiene, health and safety

Risks related to safety and hygiene should be minimized and in accordance with local laws.
Demonstrates basic understanding of the local laws that apply to safety and hygiene when using espresso equipment and cleaning chemicals
The use of safe and hygienic work practices including:
Washing hands before preparing espresso and after eating, drinking, smoking etc
Keeping body and clothing (including apron) clean and hygienic
Using and cleaning machines safely – according to manufacturer’s instructions and local laws
Using cleaning chemicals safely – according to manufacturer’s instructions and local laws
Serving drinks safely and hygienically (Avoiding handling lip of the cup; aware of dangers of hot liquids/spillages)
Demonstrates safe and hygienic work practices when preparing and serving espresso beverages

Customer service

The role of a barista

To prepare beverages correctly
To communicate information to customers
To represent the industry and the work of other coffee professionals
Defines the role of the barista in the customer experience and specialty coffee industry
The principles of customer service cover products, atmosphere, work environment and service
Lists the 4 aspects of customer service

Cleaning, Maintenance and troubleshooting

Regularly cleaning the machine creates beverages that taste good, protects the long-term health of the equipment, and maintains a positive image to customers;Describes the importance of and demonstrates good techniques for daily cleaning of the grinder and espresso machine.

Good practice for daily cleaning of equipment includes:

Thorough cleaning of the steam wand.
Wiping drying the bean hopper.
Emptying the doser chamber and brushing out all excess ground coffee beans thoroughly.
Wiping splashes and spills on outside of grinder and machine.
Back flushing the espresso machine with coffee detergent at least once a day.
Brushing and cleaning group heads of all excess coffee beans and oils.
Flushing and cleaning steam wands.
Removing and cleaning drip tray.

Lists or describes the hygiene implications and operation issues (eg blockages) resulting from not properly purging and wiping the steam wand.

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What is coffee ?

Saeed Abdinasab — Thu, 11 Jul 2019 11:40:14 +0000

What is coffee ?

Coffee trees are pruned short to conserve their energy and aid in harvesting, but can grow to more than 30 feet (9 meters) high. Each tree is covered with green, waxy leaves growing opposite each other in pairs. Coffee cherries grow along the branches. Because it grows in a continuous cycle, it’s not unusual to see flowers, green fruit and ripe fruit simultaneously on a single tree. It takes nearly a year for a cherry to mature after first flowering, and about 5 years of growth to reach full fruit production. While coffee plants can live up to 100 years, they are generally the most productive between the ages of 7 and 20. Proper care can maintain and even increase their output over the years, depending on the variety. The average coffee tree produces 10 pounds of coffee cherry per year, or 2 pounds of green beans. All commercially grown coffee is from a region of the world called the Coffee Belt. The trees grow best in rich soil, with mild temperatures, frequent rain and shaded sun.

Botanical classification

Coffee traces its origin to a genus of plants known as Coffea. Within the genus there are over 500 genera and 6,000 species of tropical trees and shrubs. Experts estimate that there are anywhere from 25 to 100 species of coffee plants. The genus was first described in the 18th century by the Swedish botanist. Botanists have disagreed ever since on the exact classification, since coffee plants can range widely. They can be small shrubs to tall trees, with leaves from one to 16 inches in size, and in colors from purple or yellow to the predominant dark green.

In the commercial coffee industry, there are two important coffee species — Arabica and Robusta.

Coffea Arabica — C. Arabica

Varieties: Bourbon, Typica, Caturra, Mundo Novo, Tico, San Ramon, Jamaican Blue Mountain

Coffea Arabica is descended from the original coffee trees discovered in Ethiopia. These trees produce a fine, mild, aromatic coffee and represent approximately 70% of the world’s coffee production. The beans are flatter and more elongated than Robusta and lower in caffeine.

On the world market, Arabica coffees bring the highest prices. The better Arabicas are high grown coffees — generally grown between 2,000 to 6,000 feet (610 to 1830 meters) above sea level — though optimal altitude varies with proximity to the equator. The most important factor is that temperatures must remain mild, ideally between 59 – 75 degrees Fahrenheit, with about 60 inches of rainfall a year. The trees are hearty, but a heavy frost will kill them. Arabica trees are costly to cultivate because the ideal terrain tends to be steep and access is difficult. Also, because the trees are more disease-prone than Robusta, they require additional care and attention.

Coffea canephora — C. canephora var. Robusta

Variety: Robusta is a one canphora variety

Most of the world’s Robusta is grown in Central and Western Africa, parts of Southeast Asia, including Indonesia and Vietnam, and in Brazil. Production of Robusta is increasing, though it accounts for only about 30% of the world market. Robusta is primarily used in blends and for instant coffees. The Robusta bean itself tends to be slightly rounder and smaller than an Arabica bean. The Robusta tree is heartier and more resistant to disease and parasites, which makes it easier and cheaper to cultivate. It also has the advantage of being able to withstand warmer climates, preferring constant temperatures between 75 and 85 degrees Fahrenheit, which enables it to grow at far lower altitudes than Arabica. It requires about 60 inches of rainfall a year, and cannot withstand frost. Compared with Arabica, Robusta beans produce a coffee which has a distinctive taste and about 50-60% more caffeine.

The Anatomy of a Coffee Cherry

The beans you brew are actually the processed and roasted seeds from a fruit, which is called a coffee cherry. The coffee cherry’s outer skin is called the exocarp. Beneath it is the mesocarp, a thin layer of pulp, followed by a slimy layer called the parenchyma. The beans themselves are covered in a paper-like envelope named the endocarp, more commonly referred to as the parchment. Inside the parchment, side-by-side, lie two beans, each covered separately by yet another thin membrane. The biological name for this seed skin is the spermoderm, but it is generally referred to in the coffee trade as the silver skin.

In about 5% of the world’s coffee, there is only one bean inside the cherry. This is called a peaberry (or a caracol, or “snail” in Spanish), and it is a natural mutation. Some people believe that peaberries are actually sweeter and more flavorful than standard beans, so they are sometimes manually sorted out for special sale.

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Different perspective of coffee history

Saeed Abdinasab — Wed, 10 Jul 2019 16:56:42 +0000

Different perspective of coffee history

If you’ve ever wondered about these questions, get ready to find out the answers. I’m going to take you through a very brief history of coffee consumption, from the 1400s through to today.

Traditional Coffee Consumption is about Guest Rites & Politics effect It’s hard to trace the consumption of coffee back to its first discovery. It seems to have emerged somewhere in Africa and the Middle East, perhaps as a form of medicine or stimulant. However, the only thing we can say for sure is that, in the 1400s, it was being brewed in Sufi monasteries. Traditional coffee consumption in the Middle East used coffee to welcome guests and as a backdrop to negotiations. It was often a ritualized experience that took place in the home. During the Ottoman Empire, coffee also started to be sold at marketplaces before becoming favored at court. From there, the coffee house emerged, And as coffee spread to Europe – and then, through European imperialism, further around the world – its association with politics, male social circles, and liberal thought solidified. From Sweden to Colombia, the ruling classes developed anxieties that the drink was a front for fomenting political and social unrest. Religious leaders, too, saw the café as a place of dangerous thought: in 1702, ministers in Salem mocked the “learned witlings of the coffeehouses” for doubting that witchcraft might exist. These attitudes continue up to the 1800s, when coffee culture started to resemble modern-day coffee consumption. The first wave coffee is marked by its increasing availability. While coffee used to be a drink of the elite, whether they were royalty or simply intellectuals, the first wave brought it into the kitchen. During the 1800s, Folger’s and Maxwell House opened up shop. Both instant coffee and the percolator, a coffee-maker that remained in wide use until the 1970s, were also invented this century. Then, in the early 1900s, the espresso machine appears – and shortly after that, Nescafé and freeze-dried instant coffee do as well.

While instant had already existed, freeze-drying technology allowed it to stay good for longer, making it both easier and cheaper to transport over long distances. What’s more, US American soldiers stationed abroad, in countries like Korea, helped instant coffee consumption to become more widespread. The second wave is marked by an increasing concern over coffee quality and the specialty experience. Starbucks was founded in 1971, in 1974 Erna Knutsen used the phrase “specialty coffee” in Tea & Coffee Trade Journal, and in 1982 the Specialty Coffee Association of America was founded. This movement was also shaped by the Colombian coffee icon of Juan Valdez, who first appeared in the late 1950s. A fictional character created by the country’s national coffee association, FNC/Café de Colombia, for their marketing campaigns, he became famous across the US. His role was to remind people that some coffees really do taste better than others.

With the third wave comes a focus on the story behind the cup. The coffee variety, country of production, terroir, processing method, roast profile, brewing method… Consumers started to realize the impact that all this can have on the taste of the final coffee. On some coffee farms, experimental processing methods also emerged in an attempt to cater to this new, more discerning type of consumer. That isn’t to say that all third wave coffee was based on new technology: the Chemex, for example, was invented in 1941. However, there was a new interest in complexity, more acidity, and how to manipulate brewing to taste the unique flavours of the coffee beans themselves.

The term “fourth wave” is a divisive one: some believe it doesn’t exist beyond marketing. Others argue that it could be used to indicate a drive towards greater use of technology and science in coffee brewing. For now, however, most people consider us to still be in the third wave of coffee.

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