Useful Roasting Technique Tip according to the moisture of green beans

Greetings, this is CATCH MIND. Today, We are going to talk about useful Roasting Technique Tip and a guide to develop a roasting profile according to the moisture of green beans.

 

 

 

In the following few posts, we will be going to discuss more about the useful technique tip. Before roasting, you would have to develop a roasting profile and this varies according to the moisture content, density, size and processing method of the beans.

 

Today, we will look into the most important factor in developing the roasting profile, the moisture content of green beans. In addition to that, we will also touch on the beans with low moisture content, past crop or old crop.

 

The moisture content of green beans

The beans are categorized as New, Past and Old crop depending on the storage period after the harvest. Past Crop, after 1-2 year of harvest, the moisture content of beans drops to 10% of less. If you roast them the same as the beans with the moisture content of 12%, it would likely to have defects during the roasting.

 

 

 

What role does moisture play during roasting

While roasting, the moisture inside green beans act as a heat transmitting medium. The moisture delivers the heat inside a drum to the center of beans. The heat gradually travels from the outer layer of beans to inside with moisture. Through this process, the beans can be roasted thoroughly without burning.

 

Generally, the initial temperature to 150 degree (302℉) during the roasting process is called the drying stage. Terms are different in each book but the contents are the same.

 

 

Understanding the roasting profile and drying stage

Drying stage in roasting means the roasting phase 'from the initial temperature to 132 degree (270℉)' or 'from the initial temperature to 150 degree (302℉)'. In this stage, organic reaction happens as well, but in terms of moisture, this is when the moisture in the bean dries.

 

Thus, the duration of this stage must be adjusted with the amount of heat input, temperature input and other variables. In other words, you must consider the moisture content of green beans before developing the duration from the initial temperature to 150 degree (302℉).

 

And while you may also emphasize the specific characteristic of the beans or hide the downsides by adjusting the drying stage, this kind of technique is only possible when the beans contain a huge amount of moisture.

 

 

Roasting technique when the moisture content is low

Some roasters may not be able to get the green beans with high moisture content. This is due to the limitation of distribution channel. Moreover, the beans from some part of Africa purposely decrease its moisture content before shipping in order to prevent the quality deterioration.

 

For Past Crop or Old Crop which contain low moisture, you do not have much choice, no matter how good specialty grade they are. In such case, you should shorten the drying stage rather than trying to emphasize the beans' characteristic.

 

In other words, you must increase the temperature input and heat input, and minimize the beans' drying period by quickly raising the temperature to 150 degree (302℉). That's why many experts, if they were given the option to choose between specialty beans with low moisture content and commercial beans with New Crop, which is high in moisture content, they tend to choose the one with higher moisture content.

 

 

When the drying stage is too long

When the drying stage of beans with low moisture content gets longer, the beans might show some flaws like dry straw taste, spicy taste and such.

 

Lastly,,,

Today we have talked about the effect of moisture content on roasting results. Among many variables, green beans' moisture content must be considered first, so I brought this topic before anything else. From now on, we will talk about the density, processing method, size and other variables as well.

 

Thank you for your time.

 

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