How to Build a Quality Control System for Roasting Beans 

Preface: What roast bean control system can most effectively serve the roasting?



In line with the continued development of artisanal coffee and its culture, people no longer drink coffee simply to receive a jolt of energy. Coffee has become a way of life and more people are choosing to purchase freshly roasted beans to brew themselves.

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When the raw green beans are roasted into their coffee color, a process that involves over 600 aromatic compounds from rich and high-quality flavors brings the senses great enjoyment. The quality of coffee is becoming more and more important, thus implying more rigorous quality control for roasters.

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In the last article, we visited and shared the experiences of bean roasting in roasteries both domestic and foreign.


Based on these valuable experiences, today we would like to discuss how to build a quality control system for roasting beans.

What quality control system for roasting beans can most effectively serve the roasting?

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Answering this requires that we clearly know which factors affect the quality of the roast in order to establish a reasonable and objective quality control system.



Physical Conditions of Raw Beans



We all know that sixty-percent of a good cup of coffee relies on the quality of the raw beans. It is therefore necessary to test the physical conditions of raw beans and whether or not they meet the company’s standards, including volume of water, density, and defect rate. 

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The testing of the physical conditions of raw beans can be divided into two stages: sample testing before selection and purchase and monthly inspection after purchase.

Procurement Gradation Log for Torch Coffee Labs

Procurement Gradation Log for Torch Coffee Labs

When raw beans are ten- to twelve-percent dried, its germs remain in a dormant state. Raw beans will be affected by the moisture content and the heat of their environment. If storage conditions are inadequate, raw beans will age quickly or absorb other smells, resulting in loss of flavor or peculiar aromas.

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It is thus critically important to make regular spot-checks.



The Testing of Roasting Conditions 



When the conditions of raw beans are good, roasting determines the fate of the coffee.

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Effectively testing the results of the roast is extremely important. I will introduce several methods summarized in past works to everyone:

1. Roast Profile and Color Value 

The roastery often sets the roast profile, but unpredictable weather, the amount of beans, and even the order of the roast all can affect the final product.

One must maintain the same roast conditions as much as possible with the most optimal roast profile (of course, this is difficult for most roasteries to do therefore one must rely on the experience of roasters to implement fine-tuning). 

Yunnan Natural Roasting Profile

Yunnan Natural Roasting Profile

The color shade reflects the depth of the roast in the finished beans. It is directly related to the produced flavor. It could be said that roast color value is one of the easier detection methods to quantify. Generally, the disparity between what is allowable and the preset color value is roughly five units.

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If the roast profile and color values are within reasonable ranges, there is essentially no problem. This is a good method for roasteries that need to comply with same-day shipping.  


2. Cuping Test


The cuping test is both the most direct and also subjective detection method.

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In order for the cup test to accurately reflect the quality of the finished beans, it must adhere to the following requirements as much as possible:



  • Cup test personnel must conduct periodic calibration, in order to ensure  the importance of perceptive consistency;

  • In addition to roasters, others should participate in the cup test. It is easy for roasters to become influenced by their roasting ideas. During the cup test, there are both ”good and bad” expectations;

  • It is best to not perform the cup test on the same day as the roast, because the roast aroma and its further developments can affect judgment.



It is also a good method to quantify the concentration of fluid coffee while conducting the cuping test through using concentration testing equipment.

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If the TDS measures around 1.05, the cup extraction ranges between eighteen- to nineteen-percent, indicating favorable roasting conditions. The TDS is too low, the roast may be underdeveloped.

 

3. Customer Experience


Coffee practitioners are accustomed to using the cup test to quickly test the quality of the coffee in one concentrated burst but often forget that customers do not drink coffee like this in their daily life.

It is thus also useful to test coffee in a way that mirrors how customers brew their coffee as well as testing changes in the coffee flavor at later stages of development to adhere as closely as possible to the taste buds of the customers.

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After collecting feedback from their market, coffee practitioners should implement corresponding adjustments. Our ultimate goal for quality control is to allow customers to drink an enjoyable cup of coffee.


In addition to controlling the roasting process, many other aspects are involved in allowing customers to purchase satisfactory coffee beans.

A reasonable quality control system for roasting beans should be built in accordance with each company’s situation while also striving to offer a consumer‘s utmost experience that will not disappoint! 





Are you afraid of the "sour" in coffee?

Introduction: Perhaps you will fall in love with the sour coffee that you are afraid of.

On a sunny morning, you go to a cafe to order a cup of coffee and take a sip. You get a mouth full of “sourness.” How would you react?

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Nowadays, more and more cafés are appearing in the streets of cities and there is more and more abundance of coffee drinks that are offered by different styles of cafes.

The coffee drinks that we have tasted no longer only bitter. There is also more and more "sour" coffee as well as many fruity type of coffee. It makes some consumers who do not like sour drinks have do not know what to choose.

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The "sourness" that many specialty coffee people love, has made many consumers want to avoid. Is "sour" coffee that terrible?



Random survey

We randomly interviewed dozens of coffee consumers in various industries and asked them about their attitude towards “sour” coffee. We compiled several interview records that can represent the majority as follows:

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We are finding that even in the city of Pu’er where people love eating sour food like sour papaya and sour mangoes still many consumers cannot accept the acidity in the coffee.

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The reasons are roughly the following three:

1. The traditional impression of dark roasted coffee makes people think that coffee should be bitter. Connecting sourness with food rottenness.

2. The bad acid in the coffee is too irritating and unacceptable.

3. The person’s stomach cannot handle sour coffee.

It can be seen that two-thirds of people are not really unable to accept sour coffee because they have not drunk a cup of good quality sour coffee. Some people have not even tried it out leaving no reason not to like it. Serving in the store, most baristas will respect the customer's choice. If you say that you don't like sour coffee, they will not recommend any fruity-type coffee for you. Maybe you will lose the chance to encounter a good cup of coffee.

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If your stomach can take it and you are not a person who refuses sourness, we encourage you to find a cup of good quality, sour coffee that you love.


Why?

The coffee cherry is fruit.

The coffee tree belongs to the Rubiaceae genus. When the coffee cherry is ripe, it is like a red cherry. It doesn’t have much pulp but it is very sweet. Unlike other fruits, coffee beans(seeds) are the core of the fruit thus it is reasonable to have acid in the coffee.

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In the early days, people mostly drank coffee for it’s caffeine and did not care about the flavor. Many roasters roast coffee till it’s dark because it is beneficial for the preservation and stability of coffee. Therefore the impression that "coffee is bitter" has also imprinted in people's minds.



Coffee varietal and growing conditions.


We find that many coffee advertisements would use the words “high altitude” and “Arabica varietal.” There are reasons why businesses list these words as a symbol of good coffee.

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Coffee is grown in tropical and subtropical regions and the higher the altitude, the greater the temperature difference between day and night. The coffee ripening cycle is lengthened and there is more time for respiration to produce flavors within the coffee beans.

A variety of high-quality organic acids such as citric acid, malic acid, etc., also start to accumulate at this time.

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Arabica is a relatively broad name for coffee varietals and the Robusta varietal is often compared with it. Because of different genes, growth environment, etc., the organic acid, sugar, and other nutrients in the Robusta coffee beans are much lower than the Arabica, which makes it boring to drink.

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Because of Arabica’s rich nutrients, it’s acid and sugar make it taste clean and smooth causing it to be favored by more people.


Processing


Common coffee processing methods can be roughly categorized as natural, honey, and washed. In conventional processing, the acidity of the washed coffee is brighter and easier to be perceived than other processed coffee.

(Washed processing)

(Washed processing)

On the other hand, because honey and natural coffee beans are dried with mucilage or pulp, there are more opportunities for microbial fermentation than washed coffee and different chemical compounds are being produced.

(Honey processing)

(Honey processing)

(Natural processing)

(Natural processing)

It will make people feel that the acidity is not very predominant but that the sweetness is stronger. Therefore, you can make your choice of taste preference based on different processing methods.


Roasting


When roasting coffee the darker roast it is the higher the degree of caramelization will have, and the more the acid will be damaged.

For high-quality coffee green beans, light-to-medium roast is the right choice, exposing it’s rich flavors such as a floral and/or fruity fragrance.

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This is also why specialty coffee roasters are leaning more towards roasting their coffee light, showing more of the charming characteristics of coffee.



Taste effect


Imagine if you are eating an apple, a pineapple, or a kiwi and you can only taste the sweetness from them. Would you still like them?

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Would you feel like you are eating fake fruits? This is because the four tastes we often mention “sourness, sweetness, bitterness and saltiness” interact with each other. Sourness, sweetness and a little bit of saltiness will make the flavor taste three-dimensional.

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Therefore, the acid in the coffee also has the same pleasant taste effect which can enhance the winey and fruity flavor in the coffee.


After the summary above, did you find that the "acid" in coffee is not so terrible?

The combination of high-quality acid and pleasant sweetness gives us an enjoyable experience like drinking fruit juice. Although it is a personal preference to choose to drink a cup of sour coffee, it is still such a regret if you miss something you might like because of some misunderstandings.

If you are interested in acidity, next time you go to a coffee shop let the barista recommend an excellent fruity type of coffee for you.