Improving quality, nutrition and health impacts of inclusion of cassava flour in bread formulation in West Africa (Nigeria and Ghana)

In the sub-Saharan region, particularly in Nigeria and Ghana, cassava is a key staple and priority root food crop that is widely cultivated and consumed. Nigeria is the world’s top producer of cassava yielding close to 46 million tons of cassava per year. In both Nigeria and Ghana, the cassava crop is amongst the most significant dietary energy sources giving it a pivotal role in these countries’ efforts towards attaining food security, nationwide health and good nutrition.

In addition, cassava plays a key role in food security and income generation for millions of poor farmers and their families. It is grown all year and can be harvested anytime from 7 up to 18 months after planting. Due to its bulkiness and perishability, it is preferable to consume cassava in its growing communities in processed forms. While cassava roots and leaves are both edible, cassava leaves are good source of vitamin A, vitamin C, iron, calcium and protein.

The roots of sweet cassava varieties may be eaten raw, boiled in water or roasted in an open fire. However, cassava roots primarily those of the bitter variety, contain cyanogenic glucosides which need to be destroyed prior to consumption. This is usually done by slow cooking the roots in water. Once slowly cooked, cassava roots can be pounded alone or in combination with other starch staple foods such as yam, cocoyam, sweet potato, etc., and then eaten with soup.

Furthermore, cassava was and continues to be very versatile in other sectors as its derivatives in the form of flour and starch are applicable in many types of food and other industrial products. Cassava roots, at the time of project initiation, could be processed into modern cassava products such as cassava meat cakes, chips, relish, flakes, cookies and strips. About 84% of the cassava in Nigeria is consumed as food such as fufu, akpu, garri and flour. However, at the time of the inception of this HQCF project, cassava’s potential for industrial utilization was yet to be adequately realized. Consequently, Nigeria at the time still spent a lot of foreign exchange on importing starch and wheat flour, while income to farmers and cassava processors remained low due to poor value addition.

The two major cassava variations grown in Nigeria are the sweet and bitter varieties. While both types of cassava contain anti-nutritional factors and toxins, the bitter varieties contain much larger amounts of these toxins and thus, must be properly prepared before consumption. When not properly prepared, cassava can contain residual cyanide which can cause acute cyanide intoxication, goitres and even ataxia or partial paralysis.

Conversely, certain properties of cassava flour and starch such as physical, chemical, physiochemical, pasting and thermal parameters are important and add to its usefulness in the food industries. More so, functional characteristics have been correlated with certain key qualities of the products resulting for such flours.

Granulation characteristics of milled flours, for example, affect the rate of hydration and swelling capacity during processing while, water binding and absorption capacities, swelling power and solubility affect the carbohydrate quality, viscosity and gelling ability of the flour/starch. Given these known properties, at the time of project initiation, there was increasing interest in the use of cassava flour and starch in food product development, the availability of information on their chemical, functional and pasting properties hoping that this would aid in the development of a processing protocol of variations of value-added products.

Coming into this project, cassava had enormous food and socio-economic implications in Nigeria and Ghana however, both countries were seen to be in investing a significant amount of their foreign reserves in wheat imports which came largely in the form of flour for bread production. There were, therefore, huge incentives to reduce what imports by replacing wheat flour with cassava flour in composite flour in order to save the countries billions of dollars annually.

Furthermore, composite cassava-wheat flour has the ability to strengthen the cassava value-chain which results in several socio-economic benefits. Prior to the HQCF project, recipes exploring different formulations for cassava composite bread had been studied under laboratory conditions with limited industrial considerations. Differences were found to exist in the quality of bread types across bakers and thus, there was a need to standardize recipes for optimum bread quality.

During the development of HQCF project, a knowledge gap existed in which there was a lack of information on standardized cassava wheat composite recipes commonly for making bread. This dearth of information was particularly true in Ghana where there existed a variety of bread types whose acceptability by stakeholders (bakers, middlemen and consumers) in the bread value chain as well as the products’ contribution ot good health was unknown.

Additionally, there was an increasing prevalence of diabetes mellitus which was linked to a high consumption of energy dense products like cassava. This health issue was exacerbated by the increase in sedentary urban lifestyles.

Considering the high and rising consumption levels of bread at the time, the glycemic index of bread can have drastic health implications affecting several millions of people in the target countries. It was clear at the time that despite the apparent indication that the inclusion of high-quality cassava flour (HQCF) in bread might reduce its glycemic index, there was a clear absence of scientific data to help guide policy on nutritional implications of incorporating cassava flour in bread.

The roots and leaves of different varieties of cassava contain varying amounts of cyanide which is known to be toxic both to humans and animals which presented another important health issue in the regions. In this regard, it was important to identify and select low cyanide content varieties with appropriate processes adopted to reduce if not eliminate the cyanide load in cassava products. It was not clear how the move to incorporate cassava in flour bread formulations in both Nigeria and Ghana would affect the several millions of bread eaters in the region.

Prior to our partnership in this HQCF project, IFAD had been playing a role in helping to boost cassava production and continued to work with several African countries to enable smallholder farmers to increase their yields and income from cassava productions. IFAD had also been supporting the development of efficient markets for cassava that benefited producers and processors. Thus, this project was timely and was developed to support smallholder farmers and processors while striving to enhance nutrition-sensitive agriculture and value chains. Ultimately, though this HQCF project was funded by a small grant awarded to the International Institute for Tropical Agriculture (IITA) in collaboration with McGill University, the lessons and experiences emanating from the project were used to strengthen IFAD loan portfolio projects.

The overarching project goal was to improve food security in Nigeria and Ghana through the use and diversification of cassava. By optimising the quality, nutrition and health implication of HQCF as well as promoting household incomes and employment creation targeting rural communities and youth, the effects of this in the long-run, would contribute to the reduction of poverty, malnutrition and improve health in these countries. The target population was comprised of poor rural farming communities that were largely dependent on cassava as a food crop as well as for its income generation, cassava processors and end users of high-quality cassava flour and starch such as bakeries and confectionaries.

To begin the HQCF project, questionnaires to survey SMEs, farmer and end-users of HQCF and cassava were designed and pretested. Enumerators were selected and trained to administer the surveys. Cassava producers were selected and added value to the Africa database and interaction with the National Secretariat of the Nigerian Cassava Processors and Marketers Association.

The SMEs selected were Oasmal, Jait Farms, Bismonco, Jonaks Oshwa, Mic-Makin, Open-Doors, Fagwell, Fadette and Matsol.

The specific project objectives were:

• To screen the cassava varieties for optimal production of high quality and nutritious bread
• To conduct and audit high-quality cassava flour processors to assess their technological and operational constraints and opportunities
• To study the physiochemical profiles of flour and starches from various cassava varieties
• To improve the nutritional content of HQCF composite bread

Cassava varieties used for industrial HQCF processing

A large number of different varieties of cassava exist with several new and improved varieties developed in the decade prior to the start of this project and these can have very different physiochemical and processing characteristics. Thus, it was important to screen the varieties of cassava for ones that deliver acceptable quality characteristics and that meet end user requirements as needed. This was achieved though a national survey that was designed and implemented to ascertain cassava varieties that were predominantly used by the HQCF processors.

Audit of high-quality cassava flour producers

For this component of the project, data was collected from both primary and secondary sources. The primary data collection was obtained through the use of structured questionnaires as well as in-depth interviews of HQCF processors and bakers. In contrast, the secondary data was obtained through the review of journals, technical documents, government gazettes and published materials from the Ministry of Agriculture among others.

Physiochemical profiles, functionality of cassava flour as well as attributes of HQCF composite bread

While different cassava flour processors use different processing and drying systems, at the time of this project’s inception, there was no information on the quality of HQCF flours from the various processors in the regions. Thus, us part of this project, a study was designed to assess the physiochemical profile of flour and starches obtained from various HQCF processors in Nigeria. Furthermore, bread samples were produced from the flour samples and their physical characteristics then evaluated using standard methods.

Improving the nutritional content of HQCF composite bread

At the time of this project, it was known that substituting wheat flour with high-quality cassava flour decreases the protein content of the composite flour and reduces nutritional quality of the resulting bread. Subsequently, this component of the project involved conducting studies to examine the potential of improving the protein content of composite bread by the addition of low cost spent yeast.