October 11, 2022

Exploring coffee grading systems: Tanzania


According to the International Coffee Organisation, Tanzania produced around 900,000 60kg bags of coffee in 2020, making it Africa’s fourth-largest coffee-producing country in that year.

The East African coffee origin produces both arabica and robusta in significant volumes. However, as a result of this, Tanzania has rejected other countries’ grading standards, and instead developed its own unique classification system.

Classifications for Tanzanian coffee depend on a number of factors, including species, bean size and density, processing method, and cup characteristics.

To learn more, I spoke with local coffee professionals. Read on for their insight on how coffee is graded and classified in Tanzania.

You may also like our guide to Tanzanian coffee production.

tanzanian coffee farmer tending to his plants

An overview of coffee production in Tanzania

Tanzania produces both arabica and robusta, with the former accounting for up to 70% of the country’s total coffee production volumes. Some of the most common arabica varieties include SC 3, SC 11, SC 14, SC 9, and KP 423.

Most of the arabica in the country is planted in the Southern Highlands, which includes the Mbeya and Songwe regions. Arabica is also produced in northern Tanzania, including on the slopes of Mount Kilimanjaro and Mount Meru. In more northern regions of the country, the main growing areas are Moshi, Arusha, Tarime, and Kigoma. 

Both the Southern Highlands and northern parts of Tanzania generally receive higher levels of rainfall and have cooler temperatures, resulting in more ideal growing conditions for arabica.

Robusta, on the other hand, is primarily produced in northwestern Tanzania, including areas close to Lake Victoria in Kagera. This region generally experiences higher temperatures which are more suited to growing robusta. 

Despite being Africa’s fourth-largest coffee producer, Tanzanian coffee farmers have experienced a number of difficulties over the past several decades – such as a rise in cases of coffee wilt disease in the 1990s, a widening generational gap in coffee production, and low farmgate prices.

Tanzania.  Coffee Beans from Inside the Hull.

What affects coffee quality in Tanzania?

Lucia Njau is a Q grader based in Tanzania. She explains that coffee quality can unfortunately vary significantly in the country.

Historically, Lucia says that some Tanzanian farmers used to add seeds and beans after their coffee was dry milled to increase the weight and artificially inflate their yield. 

However, she notes that this problem has been mitigated in recent years as producers have become more educated about post-harvest processes.

Processing in Tanzania

Processing has a significant impact on coffee quality in Tanzania. Lucia explains that most robusta farmers use one type of processing method.

“Last year, some producers processed washed robusta, but the majority of them use natural processing methods,” she says. “There is still a lack of knowledge about washed processing, so most farmers use natural processing because they believe it to be less expensive and easier to carry out.”

Tanzanian arabica farmers, meanwhile, tend to produce fully washed coffees, which are processed at central pulping units (CPUs) run by co-operatives.

Johnstone Mgangi is a coffee exporter and quality control professional, with extensive experience in the Tanzanian coffee industry.

He says that while interest in washed robusta is growing, the Tanzanian Coffee Board is attempting to implement best practices for processing methods in the country’s coffee sector as a means of improving quality.

Depulping is also a key step for quality control, especially for washed coffees.

However, some smallholders in Tanzania own their own hand pulpers, which allows them to remove flesh of the cherry without sending coffee to a CPU. In Tanzania, these are referred to as home processed (HP) coffees.

After depulping, HP coffees are usually fermented between 24 to 48 hours before being dried. According to Lucia, one of the biggest challenges with HP coffees is a lack of quality control.

“For instance, some farmers will harvest their coffee, but they won’t depulp it on the same day,” she says. “This has a negative effect on quality because the cherries will start to ferment on the side, which results in ‘foxy beans’ – a defect that creates unpleasant fermented flavours.”

Furthermore, while some producers do have access to the right facilities for depulping and fermentation, drying can still be an issue.

Overall, there is a lack of raised drying beds in Tanzanian coffee production, which means coffee often has to be dried on patios, which can sometimes impart earthy or silty flavours into the beans. In the long run, this can result in lower cup scores.

The role of co-operatives

Johnstone tells me that some practices that are popular among co-operatives in Tanzania can lead to lower quality coffee. 

“Unfortunately, even for farmers that follow best practices and deliver high-quality parchment to the co-operatives, all of the coffee is then grouped together under the same label,” he says. “This likely means that the overall price they receive for the lot is likely to be lower, even if some producers have contributed higher-quality, well-processed coffee.

“Most co-operatives also operate or own a share in some of the country’s CPUs, too,” he adds.

Despite this, Johnstone says farmers still receive higher prices when they sell their coffee through co-ops, as opposed to those who produce HP coffees.

At a CPU, staff members are responsible for carrying out processing methods and quality control, before specialist professionals inspect the final product. Some co-operatives in Tanzania work directly with private companies which can provide professionals to oversee and advise staff on how to carry out quality checks.

“They can visit each CPU on a daily basis to ensure that quality control procedures are followed, especially for washed coffees,” Lucia says.

robusta coffee seedlings

Robusta quality standards in Tanzania

In many coffee-producing countries, green coffee is often graded according to size. To do this, screens are used, with each one using different-sized holes to separate the beans according to their size. 

Screen sizes are generally measured in increments of 1/64 inches. For instance, screen size 12 includes holes that have a diameter of 12/64 inches.

However, Johnstone says that in Tanzania, the same screen sizes are used for both robusta and arabica.

The largest screen size for robusta is known as screen 18, which is also referred to as “extra”. This size is considered the equivalent of grade AA – a high-quality grade of coffee used in countries like Kenya – and it generally receives a high point score on the Specialty Coffee Association scale.

The next lower screen size is known as screen 16 or “superior”. 

“‘Superior’ coffee has a good appearance, is free of any musty flavours and aromas, and has a minimum amount of defects,” Johnstone tells me. “It has a good cup quality, too.”

Any coffee below screen size 12 is considered as “triage” – these are very small beans mixed in with broken beans, low-quality coffee, and potential foreign objects (such as stones or small twigs).

Woman's Hand, Grading Coffee Beans.

What about standards for arabica?

Even though the same screen sizes are used to classify both arabica and robusta in Tanzania, quality control standards are usually stricter for the former.

Arabica parchment coffee is initially categorised into P1, P2, and P3 groups – depending on the quality. Each of these groups is then processed separately.

“At a dry mill, the coffee is hulled and graded depending on its bean shape, size, and density,” Lucia says.

Depending on the processing method used, Tanzanian coffee can also be categorised as either “hard arabica” (natural process) or “mild arabica” (washed process). The majority of arabica in the country is classified as “mild”.

“‘Hard’ arabica is harvested, dried, and milled,” Johnstone explains. “It is mostly produced in the Tarime region, mainly because the farmers there are more used to growing robusta – which usually undergoes natural processing.”

The official Tanzanian export grades for hard arabica are AAA, AA, A, B, PB (peaberry), C, E, F, AF, TT, UG, and TEX. These are all determined by both bean size and density – with AAA being the largest screen size and TEX being the smallest.

Typically, coffees from the Southern Highlands have a medium body and medium levels of acidity, as well as more citric, chocolate, floral, and fruit flavour notes. In particular, Tanzanian peaberry coffee is highly regarded for its high quality.

Coffee in Tanzania is then grouped into “quality baskets”, which include “grinders”, “FAQ”, and “AMEX” classifications. The AMEX category is mainly used for HP coffees, which are mostly produced in the Southern Highlands.

Most coffees from the northern regions are categorised as FAQ as they are more likely to be washed. These coffees are usually cleaner tasting and have more uniform quality than AMEX coffees.

Meanwhile, “mild” arabica is classified according to bean size and density, cup quality, number of defects, and appearance after roasting. These categories range from class 1 to class 17; the higher the screen size, the larger and higher quality the bean is – although this is not always the case as quality depends on a number of factors, including screen size. Lucia notes that most Tanzanian mild arabica is graded as Class 14 or higher, while semi-washed arabica is generally graded between 6 and 8.

“For instance, classes 1, 2, and 3 are all roughly the same size, are grey-green in colour, and have a moisture content between 9% and 12.5%,” Johnstone explains. “They usually have well-balanced acidity levels and body, and are free from any defects.”

Even within these classifications, there are further indicators of quality. Classes 1, 2, and 3 are considered “fine”, “fair”, and “fair/good”, while classes 4, 5, and 6 are labelled as FAQ+, FAQ, and FAQ-, respectively. The remaining classifications are “poor/fair”, “poor”, “very poor”, and “unclean”. 

Moshi the testing of coffee at the coffee auction

Although Tanzania’s current classification systems can certainly help to identify and differentiate coffees based on quality, Lucia hopes that further changes will be made in the future.

“Hopefully the Tanzanian Coffee Board can revise the systems to reflect the higher-quality coffees that Tanzanian farmers are growing,” she says. “These systems have been around since 2001, and since then, farmers have vastly improved the quality of coffee in Tanzania.”

In doing so, we may well see more opportunities for the country’s coffee farmers to improve their income.

Enjoyed this? Then read our article exploring coffee & direct trade in East Africa.

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