1 Introduction

Cassava is one of the oldest cultivated crops in the world; its domestication occurred approximately 9000 years ago in the Amazon region of Brazil (Alves-Pereira et al. 2018). In tropical and developing countries, cassava holds great economic and nutritional importance and feeds around 800 million people. Of the 278 million tons of cassava roots produced by 101 countries in 2018, about 60% is grown on the African continent, 30% in Asia, and 10% in the Americas (FAOSTAT 2019). Cassava is the fourth most important source of calories for the human diet in Africa, South America, and Southeast Asia, behind wheat, rice, and maize. Five African countries are among the ten largest cassava-producing countries, which account for 75% of world production (FAOSTAT 2018).

Cassava cultivars are classified in two types in Brazil: sweet cassava, aka “aipim,” “macaxeira,” or “table cassava,” and bitter cassava, aka “mandioca brava” or “cassava for industry.” These types are classified based on levels of cyanide (HCN) release, a highly toxic substance if ingested. Sweet cassava contains less than 100 mg kg−1 of cyanogenic compounds (CC) per fresh root, while bitter cassava contains more than 100 mg (Araujo et al. 2019). High levels of CC require a complete detoxification process to reduce compounds to a safe level for consumption (Montagnac et al. 2009). Cassava roots are very perishable and have a short postharvest shelf life, which severely limits their potential in the market and potential benefits to farmers. The roots exhibit visible symptoms of postharvest physiological deterioration (PPD) within only 24–72 hours of harvest (Morante et al. 2010). The darkening caused by physiological deterioration is an important factor that should be considered in root processing. Like other root and tuber crops, cassava has high water content (∼65%), which is probably the major limitation to improving the utilization potential of the crop, requiring rapid processing into intermediate products to reduce transport costs, increase shelf life, and improve storage capacity (Falade and Akingbala 2011).

In Brazil, both the cassava root and the starch extracted are processed and used to make a series of products that can be consumed directly or used as ingredients in a wide variety of foods (Fig. 7.1) (Oliveira et al. 2020a; Tomlins and Bennett 2017).

Fig. 7.1
figure 1

Diversity of products in Brazil made with processed cassava root. (Source: Figure adapted with photos from Alfredo Alves, Joselito Motta, Oliveira et al. (2020a), Podium Alimentos)

In the last 20 years, the Brazilian Agricultural Research Corporation (Embrapa) has received several demands from African cassava-producing countries and funding agencies for development projects, requesting technical collaboration from Brazil to transfer technological innovations related to the cultivation and postharvest processing of cassava. Cassava cultivation in Brazil and many parts of Africa shares many similarities between Brazil and Africa in both cultural and social aspects. The profile of cassava producers is similar, and most cassava is produced on family farms. In addition, the agroecological similarities and the great diversity of cassava processing products available in Brazil facilitate the transfer and adoption of these technologies to Africa.

Embrapa Mandioca e Fruticultura international technical cooperation program started in 2000 with the Brazil-Japan Partnership Program as a means to offer courses to technicians from Portuguese-speaking African countries (e.g., Angola, Cape Verde, Guinea-Bissau, Mozambique, São Tomé and Príncipe) and Timor East in Southeast Asia. The program was financed by the Japan International Cooperation Agency (JICA).

In this program, courses were offered to technicians, researchers, and representatives of national agricultural research institutions (NARIs), and the content focused on good agronomic practices for growing cassava, including soil preparation, planting, cultivation management, harvesting, and technologies for root postharvest processing.

2 Embrapa’s Technical Cooperation with Africa: Focus on Cassava

Between 2016 and 2019, Embrapa Mandioca e Fruticultura, which also works with tropical fruits (banana, pineapple, papaya, passion fruit, and citrus), received a total of 35 delegations, involving 205 international visitors from 62 institutions and 36 countries from American, African, Asian, and European continents (Fig. 7.2). These visits were aimed at knowledge exchange and technology transfer activities, and most of them (62%) came from the African continent, with greater interest in cassava crop (82%) (Fig. 7.3). For these visits, the trainees explored a variety of topics, including (1) postharvest processing of cassava root and starch, aiming to add value and new products from Brazil that were not yet adopted or adjusted to Africa; (2) good agronomic practices for cassava cultivation, covering technologies from planting to harvest; and (3) production and distribution of cassava seeds with good genetic and phytosanitary quality, focusing on techniques for cleaning planting material via micropropagation, multiplication, and seed distribution. The main target audience for these trainings were young entrepreneurs (technicians, farmers, and cassava processors) working on their own or in national R&D or private institutions.

Fig. 7.2
figure 2

International visits received by Embrapa Mandioca e Fruticultura for trainings and technical visits (2016–2019). (Source: NRI-Embrapa Mandioca e Fruticultura (2019))

Fig. 7.3
figure 3

Distribution of international trainings and technical visits by continent and crop of interest. (Source: NRI-Embrapa Mandioca e Fruticultura (2019))

2.1 Technical Training for Young Africans

In September 2017, the Brazil Africa Institute (IBRAF) launched the Youth Technical Training Program (YTTP) aiming to promote knowledge transfer and develop skills of young Africans in various sectors, including agriculture (AfDB 2017). Financed by the African Development Bank, this program chose the cassava production chain on which to focus the initial training on “propagation, production, and processing of cassava” for young Africans. Embrapa Mandioca e Fruticultura was invited to plan and execute this training (Table 7.1).

Table 7.1 Trainings for young Africans conducted by Embrapa Mandioca e Fruticultura and promoted by the Youth Technical Training Program, 2017–2019

The training program included theoretical classes, followed by practices in the field and laboratories, and visits to cassava processing units and cassava farmers cooperatives located in the State of Bahia (Fig. 7.4). The main topics covered by trainings included:

  1. 1.

    Postharvest processing of cassava root and starch

  2. 2.

    Good practices for cassava cultivation

  3. 3.

    Production and distribution of disease-free cassava seeds

Fig. 7.4
figure 4

Training in cassava propagation, production, and processing for young Africans at Embrapa. (a) Practical class in the field, visiting a collection of cassava varieties and field instructions for cultivation; (b) laboratory practices (micropropagation and multiplication techniques for cleaning planting material); (c) training in a cassava processing unit for preparing tapioca from starch extracted from the roots; and (d) visit to street market (diversity of cassava products for sale). Cruz das Almas-BA, Brazil, 2017. (Photos: Embrapa Cassava & Fruits)

More details about the training’s agenda are available in Table 7.2.

Table 7.2 Content of the training on “Cassava Propagation, Production, and Processing for Young Africans”

2.2 Increasing Performance of the Cassava Industry in West and Central Africa (IPCI Project)

Funded by the International Fund for Agricultural Development (IFAD), this project ran from 2014 to 2017 aiming to provide technical expertise and support to a range of national cassava projects across West and Central Africa (WCA), including Gabon, Ghana, Nigeria, and the Republic of the Congo. As part of this project, IFAD established a partnership for Embrapa Mandioca e Fruticultura to engage in IPCI activities and conducted four primary activities in 2017 (NRI 2017):

  1. 1.

    Promotion of novel and innovative Brazilian cassava products. In September 2017, Embrapa welcomed a delegation of ten people, consisting of representatives from IFAD and the project coordinating institutions, and chairpersons from cassava processing units, from Gabon, Ghana, and Nigeria for (1) visits to laboratories and experimental areas of Embrapa Mandioca e Fruticultura; (2) a visit to cassava production and processing areas in Bahia State; (3) a visit to Embrapa headquarters to discuss opportunities for international technical cooperation between Embrapa and African countries; and (4) technical meetings on cassava processing with the Embrapa cassava technical team and discussion of IPCI project. On this technical visit to Brazil, the IFAD partner researchers explored, with Embrapa researchers, Brazilian technologies related to the use and processing of cassava, at different technological levels, from artisanal (small farming) to industrial processing at medium and large scales. The visits occurred in two cassava-producing regions with different profiles regarding the use and processing of cassava roots: (1) the northeast region, where small farmers predominate and the roots are processed mainly for production of flour and starch derivatives; and (2) the southern region, where cassava is grown on a large scale for production and transformation of starch.

  2. 2.

    Embrapa publications translated. Embrapa maintains a large stock of publications and gray literature on cassava. With respect to IPCI, literature relating to postharvest and processing aspects of cassava might be especially useful. However, most of these publications are written in Portuguese. Translating these publications to English and French could have a significant impact on the African cassava research environment. Embrapa identified the most appropriate publications for the areas of utilization and postharvest processing of cassava and provided for the translation of 11 publications into French and English. In addition, Embrapa selected multimedia material (videos and documentaries) reedited with English and French subtitles.

  3. 3.

    Survey of equipment and machinery for cassava processing. Brazilian manufacturers have developed a wide range of cassava processing machines which might be useful to the cassava processing sector in Africa. Usually, contacts between cassava processors in the target countries and suppliers of equipment are ad hoc. Embrapa made a brief survey of Brazilian suppliers of cassava processing equipment and provided a list of equipment, specifications, and prices, with the key elements translated into English and French (more information available in Table 7.3).

  4. 4.

    Technical visit of Embrapa experts to target countries. Three Embrapa cassava experts visited Nigeria and Ghana, where they learned about IFAD’s ongoing activities and its projects related to cassava processing through visits to IPCI partner institutions. On the part of farmers and processors, the mission visited cassava production fields, gari processing centers, and family cassava processing units, where visitors gave practical demonstrations on how to prepare tapioca from cassava starch (Fig. 7.5a, b). These visits were important to understand the few alternatives for processing cassava roots in those countries, where they concentrate, predominantly, on gari production. The great interest shown by local farmers and processors in the preparation of tapioca, for example, highlights the technological gap and potential growth areas for strengthening technology transfer of processing tools from Brazil to Africa.

Table 7.3 Information about Brazilian manufacturers and their equipment for processing cassava roots
Fig. 7.5
figure 5

Practical demonstrations of how to prepare “tapioca” from cassava starch in the District of Baara, Abeokuta (a and b), and in Lagos, Nigeria, at a CassavaTech event (c) in 2017. (Photo credits: Alfredo Alves and Ben Bennet)

The trip culminated with “CassavaTech” in Lagos, Nigeria, where the Embrapa team organized an exhibition of cassava products produced in Brazil with practical demonstrations on how to prepare tapioca (Fig. 7.5c) and a special session on “Brazilian Technologies for Cassava: What Africa can learn from the Brazilian Cassava Industry.”

3 Major Innovations for Cassava Root Processing

Cassava roots are processed in various ways to prevent postharvest deterioration, reduce root toxicity, improve the palatability of derived products, and increase the commercial value of cassava.

Based on the training evaluations and the interest shown by the participants, we selected some technological innovations already in use in Brazil and ready for adaptation for Africa, with great potential for adoption and market opening for new products.

The innovations refer to products obtained from the processing of sweet cassava roots and from bitter cassava roots and starch. It is important to note that all products/technologies applied to bitter cassava can also be used in sweet cassava, but the reverse is not always true.

3.1 Sweet Cassava Processing

For sweet cassava, we highlight cassava minimally processed, frozen cassava, precooked and frozen cassava, cassava chips, and cassava dough for snacks. Oliveira et al. (2020a) describe in detail the preparation steps of these products, which must be carried out following good manufacturing practices.

3.1.1 Cassava Minimally Processed

Minimally processed cassava is an alternative to extend the root supply period, providing a product that is easy to prepare and more convenient for consumption (Viana et al. 2010). Minimal processing needs to be carried out in a cold environment (10–15 °C). If this is not possible, use water between 5 °C and 10 °C for root washing and sanitization. Basically, it consists of root reception, selection, washing, sanitizing, cutting, peeling, sanitizing, vacuum sealed packaging, and storage at 5 °C (Fig. 7.6).

Fig. 7.6
figure 6

Steps for preparing minimally processed cassava, frozen, and precooked and frozen. (Source: Figure adapted with photos from Oliveira et al. (2020a), Oliveira et al. (2020b), and Viana et al. (2010))

Some steps to prepare minimally processed cassava are also present in the protocol of all products, such as reception and selection, washing, sanitization, peeling, and packaging of the roots, where some good practices must be followed.

Reception and washing of fresh roots

To minimize cross contamination, the reception and washing areas for fresh roots must be separated from the internal processing areas. The roots must be harvested on the same day of processing or the day before processing and stored at night. Usually, fresh sweet cassava roots are received in boxes or bags (Fig. 7.6(1)) and washed in treated tap water with a brush to remove soil and dirt residues (Fig. 7.6(3)).


Sanitization is performed after washing the roots (with and without peel) and on the materials/tools used in the root processing. This step aims to reduce the number of deteriorating microorganisms and eliminate pathogens (which cause diseases). For each material to be sanitized, different chlorine solutions are used (Table 7.4).

Table 7.4 Sanitization steps performed in the postharvest processing of cassava

Peeling the roots

Peeling the roots must be careful as it can damage the tissues and accelerate the browning process, called physiological and/or microbial deterioration, and increase the water loss. Peeling sweet cassava roots for culinary use is usually done manually with a stainless-steel knife or with suitable peeling equipment. After removing the root tips, if the peeling is carried out manually, the cylinders are cut to approximately 6 cm in length and then peeled. If peeling is done with equipment, cassava is cut into cylinders after peeling. All the peel must be removed to improve the appearance of the product and avoid darkening (Fig. 7.7).

Fig. 7.7
figure 7

Peeling sweet cassava roots. All peel (periderm and cortex) must be removed. The presence of peel in precooked root impairs the appearance of the product (red arrow on the right). (Photo credits: Eliseth Viana and Luise Sena)

Packaging the roots

Packaging protects the product during transportation, distribution, storage, and handling against damage, shock, vibration, and compression that occur during the entire journey. The low-density polyethylene plastic bag is the most commonly used packaging for processed cassava products, as it is resistant to impact and a good water barrier. However, some products, such as flour, may use kraft paper packaging, molded as a box or bag; this material has the advantage of being recyclable and biodegradable. For fried products, such as chips, polypropylene and aluminum plastic film are recommended to prevent oil oxidation and maintain the crispness and flavor of the chips for a longer time. However, it is common to use polypropylene plastic bags for the packaging of fried chips, as they are less expensive, sold in small quantities, and easier to find. The polypropylene packaging is transparent and gives greater visibility to the product, but the chips will have a shorter shelf life due to oil oxidation.

3.1.2 Frozen Cassava

Frozen cassava is sold in whole cylinders from 5 to 7 cm in length, in pieces, or crushed to make cakes. The processing steps are the same as for minimally processed cassava with the exception of storage that is carried out at −18 °C in a freezer or cold room (Fig. 7.6).

To obtain frozen cassava, the roots must first be selected, excluding those with hard (fibrous) parts, spots, rot, or other problems (Fig. 7.8). The first selection of the roots usually occurs in the field at harvest time. To evaluate the root quality, a sample of the harvested roots that represents the variety to be processed is cooked. Only the group roots that present desirable quality (e.g., cooking in 30 minutes or less) should be processed. Roots that cook in more time must not be processed, even under pressure. Processing does not improve the quality of the processed root, so it is essential to process good quality roots to obtain a good product (Oliveira et al. 2020b).

Fig. 7.8
figure 8

Cassava roots unsuitable for processing due to the presence of dark spots. (Photo credits: Luciana Alves de Oliveira)

After the second sanitization, the sanitizing solution is drained, and the cylinders are packed in more resistant polyethylene packages. Frozen cassava can be sold in portions from 200 g to 2 kg, depending on the consumer market. The packages are sealed and placed at −18°C in a freezer. Vacuum packaging is not recommended as frozen cassava can pierce the packaging.

If the processing is carried out properly, the product will last for at least 4–6 months. The roots must be placed for cooking while still frozen, and this information must appear clearly on the packaging.

Losses in the processing of frozen cassava, such as peel and tips, vary from 25% to 30% of the total weight of the roots. The tips and small pieces of cassava can be used for the preparation of other products, such as dough for snacks.

3.1.3 Precooked and Frozen Cassava

Precooked and frozen cassava is sold in the form of sticks or pieces. In this processing, the initial steps are the same as for frozen cassava (root reception, selection, washing in water, sanitation, cut in cylinders, peeling), followed by cutting into sticks or pieces, precooking, cooling, packaging, and storage at −18°C in a freezer or cold room (Fig. 7.6).

The stick is always cut longitudinally to the length of the root in the direction of the fibers. If the stick is cut across the fibers, the percentage of breakage is greater and the product length will be shorter (Fig. 7.9). The stick is cut 1 cm on the side and 5–6 cm long. For cutting the roots into pieces, the cylinder can be cut into 4–8 parts. Imperfect sticks, tips, and leftover roots can be used to produce dough for snacks.

Fig. 7.9
figure 9

Photo (a) shows the proper way to cut cassava lengthwise and with regard to thickness. Photo (b) shows improper cutting of cassava for sale, which will diminish its safety and shelf life. (Photo credit: Luise de Oliveira Sena)

After cutting, the precooking starts with 2 L of water for each kilogram of cassava root and 2% salt added to the water (20 g of salt per 1 kg of cassava root) to accentuate the flavor. The cooking water must be changed after three uses. The sticks or pieces of cassava are placed in the water once it is boiling.

The precooking time should be tested for each variety used. For example, precooking can be tested in three time periods: 2, 4, and 6 minutes. For each test, use 250 g of cassava sticks and 0.5 L of water with 5 g of salt. The precooked sticks should be frozen when submerged in water, boiled for the required time, and then fried to verify the quality of the final product. Table 7.5 shows the results of the test performed with two cassava varieties. Each variety was harvested and tested on the same day and at the same age.

Table 7.5 Tests performed to determine the appropriate precooking time for two cassava varieties processed as sticks

Precooking time can vary for the same variety, depending on the root age and environmental conditions (fertilization, rainfall, plant nutrition, soil, drought). The precooking time for a piece of root is longer than that for a root stick. Thus, tests to confirm best precooking time must also be performed.

After precooking, the sticks should be drained and placed in packs made with a resistant (thicker) polyethylene or another resistant material. The sticks tend to adhere to each other. To prevent this, place the sticks in a disorganized manner inside the packaging (Fig. 7.6(13)). The packages should then be sealed and placed in a freezer at −18 °C.

3.1.4 Cassava Chips

Another way of adding value to cassava is by producing fried snacks such as chips. The preparation of the chips includes the reception and selection of the roots, washing in water, sanitizing, peeling, sanitizing, slicing, soaking the slices in water, frying, salting, draining surface oil, packaging, and storage (Fig. 7.10).

Fig. 7.10
figure 10

Steps for preparing cassava chips. (Source: Figure adapted with photos from Oliveira et al. (2020a, b)

Peeling the entire root is important to reduce leftover tips. After peeling, the peeled roots should be submerged in treated water to remove any adhering skin. The water used in this stage can be reused for initial root washing.

The root is cut into slices approximately 0.8 mm thick. The thickness of the slice is especially important for the quality of the product (crispness). If the slice is too thick, the chips may become hard. There is cassava slicing equipment available on the market for this purpose. Slicing can occur directly into the fryer; if not available, slices must remain immersed in water to prevent them from sticking. After soaking, the water must be drained and the slices fried. Very thick cassava roots are not suitable for chips as they crack during peeling or slicing (Oliveira and Godoy 2011).

The frying oil temperature should be between 170 °C and 180 °C and not exceed 190 °C to avoid impairing the oil quality. The quality of the oil used for frying will influence the quality and shelf life of the finished product. Oil degradation will be greater the longer the period of its use. To monitor the quality and disposal point of the frying oil, there are quick tests and evaluation equipment on the market. Palm oil has higher oxidative stability (less degradation) than cotton, sunflower, and soybean oils; therefore, it is the most suitable for the production of fried products.

After frying, excess oil is drained and the chips are spread over a sheet of paper to again drain the excess. The product is salted with 1% salt: 10 g for every 1 kg of product. The addition of spices (oregano, chili powder, parsley, onion, among others) can be added at this time also. If the additional seasoning contains salt, the amount of added salt must be decreased.

The slices should be quickly packaged to prevent moisture absorption. The product should be packed in polypropylene bags, in portions of 40–80 g, stored in a dark place, and should be consumed within 15 days.

Chips may vary in quality due to factors such as the quality of the raw material and oil used, inequalities in chip thickness, temperature, and frying time. The color of the final product depends on the color of the cassava variety used, which may be white, cream, yellow, or pink.

3.1.5 Cassava Dough for Snacks

For the preparation of dough for snacks, the first steps are the same as for frozen cassava, followed by the steps of cutting the root into four pieces, central fiber removal, cooking, freezing, grinding, salting, shaping, packaging, freezing, and storage at −18 °C in a freezer or cold room (Fig. 7.11). If processed properly, the product will last at least 6 months. Before starting the dough preparation, one batch of roots should be used to evaluate the cooking time of the variety used.

Fig. 7.11
figure 11

Steps for preparing cassava dough for snacks. (Source: Figure adapted with photos from Oliveira et al. (2020a))

The cooking water is drained (Fig. 7.11(10)), and after the cooked roots return to room temperature, they should be cooled at a temperature between 4 °C (refrigerator) and −18 °C (freezer) (Fig. 7.10(11)) for 24 hours. The cooked root, still frozen, is ground in a meat grinder (Fig. 7.11(12)). Then the crushed dough is mixed with salt, using a ratio of 10 g salt to 1 kg dough (1% salt) in a mixer (Fig. 7.11(13)), adding the salt gradually while mixing the dough.

The dough can be placed in a sausage maker (Fig. 7.11(14)) to make croquettes. The machine’s screw system should rotate slowly so that the texture is uniform, and the dough does not acquire air bubbles. When the dough begins to exit the plastic section of the equipment, use hands to press the plastic section outlet (Fig. 7.11(15), red arrow) while the screw system turns. It is important to exert pressure during this step so that all air is removed from the dough. The tray that will receive the dough must be greased with a little oil so the dough does not stick to the tray.

The croquettes must quickly be cut to the same size using a knife (Fig. 7.11(15)) so that the dough does not break. The knife should be rinsed in water to facilitate cutting. To finalize the savory pastry, dip fingertips in water and mold the cut ends with moistened fingers (Fig. 7.11(16)) to round the ends of the croquettes.

Croquettes are sold frozen or pre-fried (180 °C for 35 seconds) and frozen. Fry the frozen croquettes in oil at 170 °C for 3–4 minutes in a covered pan, as the croquettes may explode if the dough is too wet.

In addition to salt, other spices can be added to the dough, such as onion, cilantro, basil, oregano, cheese, and parsley. The dough can also be used to make savory foods in different formats (“coxinha,” dumpling, rissole, gnocchi) and with desired fillings (bacon, shrimp, ground beef, chicken, cheese, among others) (Fig. 7.12). Savory pastries tend to be quite sticky and need to be breaded. The flour used for breading also removes the sticky quality of the pastries and becomes an oil absorption barrier during frying, which increases the crispness of the product.

Fig. 7.12
figure 12

Frozen (a), frying (b), and fried (c) croquettes and “coxinhas” made from stuffed sweet cassava dough. (Photo credits: Luise de Oliveira Sena)

3.2 Bitter Cassava Processing

In Brazil, bitter cassava roots are processed to produce flour (farinha de mandioca) and starch (known in Brazil as polvilho, fécula, or goma), which can be further processed into a series of products. Below, we will highlight beiju (cassava flake), tapioca (stuffed beiju), avoador (starch biscuit), and cheese bread.

3.2.1 Flour Processing

Dry flour is consumed throughout Brazil, and its production involves the following steps: washing and peeling the roots, grating, pressing, crumbling, sieving, roasting, sifting, packaging, and storage (Fig. 7.13). Fermented flour, known in Brazil as farinha d’água or farinha puba, is widely consumed in the Amazon region (North Brazil). Its production involves the same steps as dry flour, except that, before being grated, the roots are macerated (softening of the roots in a fermentative process in water, known as pubagem) for 4 days. After pubagem, the same steps as dry flour should be followed (Fig. 7.13).

Fig. 7.13
figure 13

Steps for preparing dry and fermented cassava flours. (Source: Figure adapted with photos from Oliveira et al. (2020a) and SENAR (2018))

To prepare the flour, it is important to use the same variety and the same age of cassava roots. Root washing prior to manual peeling (or maceration for fermented flour) is recommended (Fig. 7.13(1)). Processing should begin immediately after harvest. Roots must be completely peeled where the bark is not white. Partial peeling can influence the quality of the flour and lead to dark spots and/or browning in the final product.

The peeled root should not be placed directly on the ground but rather in plastic boxes and washed with tap treated water to remove sticky peels, sand, and other adhered dirt.

The next step is root grating, which is done using an electric grater, also called cevador or caititu (Fig. 7.13(6)). The grater has a cylinder, preferably with serrated stainless-steel blades (Fig. 7.13(4, 5), red arrow) that can be replaced as needed.

Excess water in the grated dough must be removed before roasting using manual (Fig. 7.13(9)) or hydraulic pressing equipment. The grated root dough is placed in raffia bags (Fig. 7.13(7)) or on fine mesh nylon screens and pressed onto pallets (Fig. 7.13(8)) to remove excess water (also called manipueira. The pressing time depends on the amount of crushed mass and the equipment used. Manipueira and cassava peel can be used in animal feed, fertilization, and irrigation.

The dough becomes compact due to compression and needs to be crumbled. This procedure is performed using the same root grater (Fig. 7.13(6)).

To get a fine dry flour (which is preferred in northeast Brazil), it is recommended to pass the crumbed dough through a hand or mechanical sieve (Fig. 7.13(10)) with a galvanized 26–28 mesh to standardize the grain size of the flour and remove the fibers (central root fiber) before drying and toasting. The higher the mesh number, the finer the flour obtained.

The dough is manually placed in the oven using a scraper (Fig. 7.13(11)). The dough should be added slowly into the oven with the stalks moving so as not to tangle.

Initially, the dough should be roasted for 20–30 minutes at 90 °C. After that time, increase the oven temperature to approximately 160 °C for up to 3 hours to reduce moisture (Fig. 7.13(12)). After roasting, the flour must be cooled and sifted to evaporate the remaining moisture (Fig. 7.13(13)). The flour grain size depends on the demand of a particular consumer market.

To keep the flour crispy, packaging for storage and sale is important. When flour is ready and cold, 50 kg plastic bags are recommended. For smaller portions, 1 kg packages of polypropylene are preferred (Fig. 7.13(14)), which preserves the low moisture of the flour. Polyethylene keeps the product crisp for a shorter time.

The flour must be stored in a dry and ventilated place with screened windows. It is recommended that the bags be stacked on pallets or crates, leaving room for air circulation between the packs (Fig. 7.13(15)). According to Brazilian legislation, cassava flour must have a maximum humidity of 13%.

Gari vs farinha d’água

The most consumed processed cassava product in Brazil is unfermented cassava flour, which is not made in other regions of the world. Outside Brazil, the main cassava product is gari. Gari was introduced in Africa in the early nineteenth century after freed slaves returned to the African continent. Today, it is the main cassava product in sub-Saharan Africa, representing 70% of the cassava consumed in Nigeria. Meanwhile, in Brazil, farinha d’água is produced, almost exclusively, in the Amazon region (Folegatti et al. 2005; Bechoff et al. 2019; Ndjouenkeu et al. 2021).

Both flours are made from fermented cassava. However, the fermentation of farinha d’água occurs in anaerobic conditions by immersing the whole root in water, while gari fermentation is aerobic: the grated root mass is pressed slowly for 2–6 days (Fig. 7.14). Gari also includes a step for “garification,” which combines stages of gelatinization (starch cooking) and gari roasting, which affect the physicochemical and rheological properties of the starch, providing this food its unique sensory and functional characteristics (Folegatti et al. 2005).

Fig. 7.14
figure 14

The steps to prepare farinha d’água and gari, including the processing differences between the two products. (1) With farinha d’água, fermentation is anaerobic and the whole roots are immersed in water, (2) while in gari, the fermentation is aerobic and the grated root mass is left to ferment during pressing. (Photos: Alfredo Alves (2-4) and Folegatti et al. 2005 (1))

Massa puba (puba dough) or carimã

Massa puba is produced from the spontaneous fermentation of fresh cassava roots (with or without peel). The roots are placed in water for approximately 5 days until they soften and begin to release the bark. Then, they are crushed in sieves and washed until only the fibers remain. The separated mass must be washed several times and dried in the sun or in dryers until a humidity of 50% is reached for wet puba (or puba úmida) and 13% for dry puba (or puba seca) (Ferreira Filho et al. 2013). Carimã is a fine flour made by crushing dried fermented roots. Puba and carimã are used in the preparation of cakes, porridge, couscous, and other dishes.

3.2.2 Small-Scale Starch Extraction (“Polvilho Doce” or “fécula”)

In the past, the cassava starch was considered the by-product of flour production. Due to the increased demand by the consumer markets for cassava products, the starch has been used to manufacture starch biscuits, tapioca, and cheese bread (SENAR 2018).

The steps for starch extraction (Fig. 7.15) are the same as for dry flour until the grating step. The crushed root dough (Fig. 7.15(6)) should pass through the starch extractor (Figs. 15.7 and 15.8) and mix with water while in the starch extractor. As the water drains out, it must be received in a glass fiber trough to separate the starch via decantation (Fig. 7.15(9)). The decanted starch is crumbled and placed to dry in the sun until it reaches a humidity of approximately 13%. The dried starch is then packaged and stored in a cool and airy place. Starch can be stored safely up to 12 months.

Fig. 7.15
figure 15

Steps for cassava starch extraction. (Source: Figure adapted with photos from Oliveira et al. (2020a) and SENAR (2018))

Sour starch (“polvilho azedo”)

The production of sour starch follows the same steps as natural starch, except that in the decantation stage, the starch is left to ferment in the tanks for a period ranging from 15 to 40 days, depending on the ambient temperature, until the product reaches an acidity of approximately 5%. The settling tanks must be under cover to avoid impurities and must be covered with ceramic or fiber tiles. During the fermentation period, the starch must remain covered by a 10 cm layer of water. If not covered, the starch exposed to air acquires a blue or purple color, which reduces its quality. After the fermentation period, the starch is removed from the tanks and taken to dry.

3.2.3 “Beijus” (Cassava Flakes) and “Tapiocas” (Stuffed Beiju)

The beijus , or tapiocas as they are known in Brazil, are produced from the starch, gum, fécula, or polvilho. Two types of this product are common: (1) beijus roasted on hot plate, crispy, without fillings and (2) soft and folded with various fillings, often called stuffed tapioca, beiju de tapioca, or simply tapioca (Motta, 2012).

These products are made with cassava-hydrated starch (farinha de tapioca or polvilho doce úmido), which is obtained by mixing a part of water with two parts, by weight, of the natural starch (polvilho doce seco) and pinches of salt. The mixture is homogenized and sieved to make it thinner.

To make traditional roasted beiju, hydrated starch is spread on a hot plate or heated pan (Fig. 7.16(1)). The drying point of the dough can be identified when the edges come loose and become brittle, like pancakes or a dry crepe. The beijus are cut on the hot plate (Fig. 7.15(2)), cooled to room temperature (Fig. 7.16(3)), packed in plastic bags or pots (Fig. 7.16(4)), and sealed, labeled, and stored (Fig. 7.16(4,5,6)).

Fig. 7.16
figure 16

Steps for preparing beijus. (Source: Figure adapted with photos from SENAR (2018))

Colored “Beijus.”

Traditionally white, beijus have been produced in new colors, smells, flavors, and nutrients when the water is replaced by fruit pulps or vegetable extracts. Tasting evaluations found that consumers preferred these products flavored with beets, onion, pineapple, guava, and passion fruit (Fig. 7.17a) (Motta, 2012). To boost cassava sales in schools, producers have also manufactured gum biscuits, cookies, and other products (Fig. 7.17b).

Fig. 7.17
figure 17

(a) Colored beijus prepared with fruits and vegetables. (b) Diversity of beijus for sale at the municipal market in Cruz das Almas, Brazil. (Photo credits: Joselito Motta)

Stuffed tapioca (“beiju de tapioca” or “tapioca recheada”)

To make tapioca, start by hydrating the natural starch (polvilho doce or tapioca seca) and adding a part of water to two parts of starch (Fig. 7.18(1)). Mix well with hands until it crumbles and add a pinch of salt. Sieve the hydrated starch (Fig. 7.18(2)) and spread it over a preheated frying pan (Fig. 7.18(3)). To spread the sieved starch, you can use the sieve or your hands. Let the starch heat up until you notice that the grains have stuck to each other, and the starch pancake becomes loose from the pan (around 1 minute) (Fig. 7.18(4)), and turn it upside down, like a pancake. Add any kind of filling (Fig. 7.18(5)) and fold the tapioca in half (Fig. 7.18(6)). Heat the tapioca a bit more on both sides to complete the process. The frying pan does not need to be greased; it should be clean and without grooves. The type of filling depends on consumer preference, such as butter and cream cheese, condensed milk, ham and cheese, meats, and a range of food mixes (Fig. 7.19).

Fig. 7.18
figure 18

Steps for stuffed tapioca. (Photo credits: Alfredo Alves)

Fig. 7.19
figure 19

Tapioca with different types of filling: (a) plain tapioca with grated coconut filling; (b) beet tapioca with scrambled egg filling; (c) cabbage tapioca with shredded chicken and mozzarella cheese filling. (Photo credits: Joselito Motta)

3.2.4 Avoador (Starch Biscuit)

Avoador , often referred to by its generic name biscoito de polvilho, but also known as peta or biscoito avoador, is a type of snack food in Brazilian cuisine. It is found mainly in the states of Minas Gerais, Bahia, and Rio de Janeiro, but is also consumed in São Paulo and Paraná. Avoador is a popular snack and side dish for breakfast (Fig. 7.20) (Sampaio and Menezes 2020).

Fig. 7.20
figure 20

Diversity of avoador biscuits and other cassava starch snacks. (Photo credit: Joselito Motta)

Both sour and sweet starch can be used to prepare avoador. For 500 g of starch, mix with 250 mL of milk, 250 mL of water, 250 mL of oil, 1 egg, and 1 teaspoon of salt.

Preheat the oven to low temperature before starting to prepare the recipe. Mix the egg and salt in a bowl. Then add warm oil and milk. Gradually add the starch and stir until you get a consistent dough. Put 250 mL of boiling water into the mix and combine all the ingredients.

Put the dough in a pastry bag (or plastic bag) with a spout. Grease a pan with margarine and make the cookies in the shape you want, but do not let the cookies touch each other while baking. The cookies should be baked at 180°C for 20 minutes.

3.2.5 Pão de Queijo (Cheese Bread)

Pão de queijo , or Brazilian cheese bread, is a small, baked cheese roll or cheese bun, and a popular snack and breakfast food in Brazil. It is a traditional Brazilian recipe, originating in the state of Minas Gerais.

Pão de queijo consists of a type of biscuit with sour or sweet polvilho plus eggs, salt, vegetable oil, and cheese, of soft and elastic consistency (Fig. 7.21). There are several different recipes that vary the ingredients and type of cheese to be used. Natural and/or sour starches can be used to prepare the bread.

Fig. 7.21
figure 21

Traditional Brazilian pão de queijo (cheese bread). (Photo: Podium Alimentos)

For 500 g of starch, add 300 mL of milk, 150 mL of oil, 3 eggs, 250 g of grated Minas cheese, and a teaspoon of salt.

In a bowl, heat the salt, milk, and oil. When boiling, scald the starch with this hot mixture, stir well, and let it cool. Add the eggs one by one, alternating with the cheese and kneading well after each addition. Grease your hands with oil if necessary.

Mold cookies 3–5 cm in diameter and place them on a greased baking sheet. Take to a preheated oven (180 °C) and bake until golden brown (around 15 minutes).

4 Closing Remarks

All the technological innovations detailed here are characterized by a high level of technological maturity, which means they are qualified technologies, fully adopted in Brazil, and, potentially, ready to be transferred directly, or with small adaptations, to other international production systems. On the other hand, their positive impacts on society do not seem to have been properly analyzed to create a vision of their success and how these technologies can be framed within the readiness scale recently developed by CGIAR (Sartas et al. 2020).

It is hoped these technology transfer trainings will allow participants to apply the skills in their own contexts. Therefore, it is important to design a training program that is sustainable and replicable in other regions or countries.

Considering this and based on the experiences acquired over the last 15 years, Embrapa Mandioca e Fruticultura has been trying to improve the implementation of international training to maximize the returns on investment.

Appropriate selection of participants is crucial. Typically, training candidates are chosen directly by the beneficiary institution, following the view that innovations can be transferred simply by intermediaries and change agents (e.g., extension workers) and then spread throughout the communities of individual beneficiaries. This conception has been widely refuted (Sartas et al. 2020).

In the first training sessions carried out by Embrapa, the African candidates selected were predominantly adult professionals, based in national R&D institutions primarily focused on administrative management activities rather than research. Usually, these individuals held administrative positions; some were not even involved with cassava crop. This lack of proximity to cassava production may have hindered their effectiveness as a technology multiplier inside and outside their institutions.

In the more recent cassava courses carried out by Embrapa, international organizing institutions (usually CGIAR and African NARIs), training sponsors, and funding agencies have selected young candidates with an entrepreneur profile, technical professionals, or recently graduated individuals linked to state institutions, private companies, and/or start-ups. Most young trainees consider training as essential to financial survival, an opportunity for them to introduce innovations in their own business and add value to their products.

Embrapa has specified how its trainings could be adapted or suited to address gender differences; however, we did not see the need to adjust the trainings to meet the preferences of men and women. The instructors – who are women and men – have noticed some differences in participation. Women showed more interest in topics related to techniques for preparing products from cassava processing. Men expressed greater interest in field activities. As the trainings occasionally require overnight stays or long hours away from home, this may create some implications that deserve attention to meet the needs and preferences of both men and women participants.

Participants of the three courses held within the Youth Technical Training Program on Cassava Post-harvest Processing (2017–2019) are already applying what they have learned in Brazil, and many of them provide to IBRAF and Embrapa with great feedback on the results of the Program at the micro level. One of the participants who founded the PaaClee Cassava Processing Company in 2014, for example, started to invest in training sessions with his employees, sharing the knowledge acquired during the 1-week course in Brazil. The YTTP on Post-harvest Processing of Cassava success also resulted in the organization of four YTTP sessions on Smallholder Agriculture with Senegalese learners and one YTTP session on Civic Engagement with Angolan learners, the first ones to be organized in bilateral arrangements, scheduled for 2021 and 2022 (UNDP-IBRAF 2020). During the Fourth International Cassava Conference (GCP21-IV), held in Benin in 2018, the young woman from Benin, Paula Gnancadja, a Bachelor in Management of Agricultural and Rural Enterprises, who participated in the YTTP training the previous year, presented the work “A Young Cassava Farmer and Processor Building a New Start-Up in Benin,” reporting the success of her start-up (ABB.Sarl), after returning from Brazil, introducing new cassava processing products, which are being very well accepted by Benin consumers. She received the GCP21-IV Best Poster Award in the “entrepreneurship” category.

The technologies that received the greatest interest in the trainings include those products made from starch (polvilhos), such as beijus, tapiocas, and biscuits (avoador), and the minimal processing technique as a means for storing roots and using it later as raw material for chips, cakes, and dough for snacks.

One of the great challenges for the implementation of training for Africans is the great cultural and language diversity, coupled with the fact that the majority of Brazilian instructors speak only Portuguese. At the three YTTP courses, most of the African attendees spoke either English or French, while the Brazilian instructors spoke Portuguese, which create some communication difficulties.

The fact that Brazil is the center of origin and domestication of cassava explains the great importance of this crop, as well as the enormous diversity of its use and processing in different regions of Brazil. This time lag and the great genetic diversity of cassava made Brazil a major source of technologies for processing, which would later be mechanized and scaled for industry. Currently, the African cassava-producing countries are investing heavily in both sectors (family and industrial) to develop their own new technologies and/or to adapt or improve Brazilian innovations according to their demands. These efforts are welcome for government development programs, because of the unquestionable importance of cassava to reduce hunger and increase the income of cassava producers and processors. Therefore, we believe that the next cassava technologies transfer initiatives between Brazil and Africa should be extended to technologies, services, and products aimed at large-scale cassava processing and cultivation.