**1. Introduction**

Fermented foods are products of edible or inedible raw materials that have undergone desirable physic-chemical and biochemical modifications through the activities of microorganisms and/ or their metabolites, but in which the weight of the microorganism (relative to substrate) in the food is small [1]. A distinct group of fermented foods is the traditional alkaline fermented products often used as food condiments/ seasoning agents [2]. Fermented foods and seasoning agents play central roles in the food and nutrition security of many nations, but particularly so in Africa, Asia, South America and Oceania [3]. As several people across the world gravitate back to "eating natural", there is a new emphasis on fermented foods and seasoning agents which are also critical cultural foods in countries and societies where they are important. In Africa, many of the seasoning agents are products of fermentation of legume seeds, a process that causes an increase, to alkaline regions, in pH of the product. This results from microbial degradation of seed proteins to peptides and amino acids and finally to ammonia [3, 4]. Fermentation of raw materials such as fish, legumes and plant oil seeds for the production of

food condiments with desirable organoleptic properties and enhanced nutritional values has historically been a popular practice in Africa, particularly in West and Central Africa. Currently, there is an upswing in the popularity of these seasoning agents, and around them new cottage industries are growing, as against the kitchen technology that sustained them through the ages [3]. This resurgence in alkaline fermented foods are results of a better understanding of fermentation processes, as well as increased knowledge of the nutritional, and health-promoting benefits of fermented foods [5]. This chapter will explore the state of biotechnological developments around these foods and seasoning agents and point the way to good manufacturing practice and industrial and market development.

#### **1.1 The beginning of fermented foods**

The art of food fermentation dates back to prehistoric times and are the oldest methods for producing new foods from existing substrates, and of prolonging the shelf life of foods [3, 6]. Historically, fermentation has been used to modify the composition of foods without any scientific knowledge of the processes or benefits, and this art has been practiced for thousands of years [7–9]. As at 2000–4000 BC, the Egyptians were producing alcoholic beverages [6]. According to records [10, 11], fermentation has been in practice also in Sudan, (1500 BC) and Mexico, (2000 BC). Despite advances in biotechnology and efforts towards industrialization of the traditional fermentations, uncontrolled traditional techniques/ kitchen technologies are still predominantly used for the processing of alkaline African fermented foods and seasonings.

Modern food technology practices such as the use of good manufacturing practice (GMP) protocols, as well as new innovations like the use of starter cultures in controlled fermentations continue to play little or no role in the developing countries. The disposition to understanding traditional food processing is now beginning to gain some ground in developing countries. It is essential to recognize the significance of biotechnology-based innovations and applications in food processing in order to ensure quality and safety of products [12]. More recently, process techniques used in traditional fermented foods are being redefined and diversified through the use of molecular biology-based tools, enabling fermentation technology around these processes to evolve towards sustainable commercialization and industrialization. This lift from artisanal production has stimulated new interests in food research, such that today a lot of scientific works [13–26] have been devoted to these fermented foods. With modern biotechnology new and better methods for processing foods under GMP are developing.

#### **2. Fermentation processes**

Across cultures, a variety of traditional techniques are used for producing fermented foods and seasoning agents. The techniques differ based on microorganisms, raw material and fermentation conditions [27, 28]. Basically, processes involved in food product development by fermentation are of four types (**Figure 1**), viz.: alcoholic, lactic acid, acetic acid and alkaline fermentation [6, 27, 29].

Alcoholic fermentation is mainly performed by yeasts leading to the production of ethanol. Products include wine, beer, other alcoholic beverages and bread. Lactic acid fermentation is driven by lactic acid bacteria (LAB), which produce organic acid and other compounds in various foods. Acetic acid fermentation is carried out by the acetic acid bacteria which convert alcohol to acetic acid under aerobic process as in vinegar. Alkaline fermentation usually takes place during the fermentation of

**17**

**Figure 1.**

*product. Source: Anal [27].*

Starchy foods Root tubers

*Current Status of Alkaline Fermented Foods and Seasoning Agents of Africa*

*An illustration of the various types of fermentations, based on microorganisms, fermentation condition and end* 

**Food group/class Substrate Derived product Country**

Cereal-based

Cassava *Garri, akpu, loi-loi* Nigeria

Maize *Ogi/akamu* Nigeria

Millet *Kenkey/banku* Ghana

Sorghum *Busa* Egypt

*lafun/aribo* Nigeria

*Kokobele* Nigeria

*Kito* Tanzania *Mawe* Nigeria (Benin) *Njera* Ethiopia *Mahewu* South Africa,

*Uji* Uganda,

*Ogi/akamu* Nigeria *Uji* Uganda,

*Nasha* Sudan *Kisra* Sudan *Bogobe* Botswana *Uji* Uganda,

Nigeria

Kenya

Tanzania

Tanzania

Tanzania

*DOI: http://dx.doi.org/10.5772/intechopen.87052*

*Current Status of Alkaline Fermented Foods and Seasoning Agents of Africa DOI: http://dx.doi.org/10.5772/intechopen.87052*

#### **Figure 1.**

*New Advances on Fermentation Processes*

**1.1 The beginning of fermented foods**

fermented foods and seasonings.

processing foods under GMP are developing.

**2. Fermentation processes**

food condiments with desirable organoleptic properties and enhanced nutritional values has historically been a popular practice in Africa, particularly in West and Central Africa. Currently, there is an upswing in the popularity of these seasoning agents, and around them new cottage industries are growing, as against the kitchen technology that sustained them through the ages [3]. This resurgence in alkaline fermented foods are results of a better understanding of fermentation processes, as well as increased knowledge of the nutritional, and health-promoting benefits of fermented foods [5]. This chapter will explore the state of biotechnological developments around these foods and seasoning agents and point the way to good

The art of food fermentation dates back to prehistoric times and are the oldest methods for producing new foods from existing substrates, and of prolonging the shelf life of foods [3, 6]. Historically, fermentation has been used to modify the composition of foods without any scientific knowledge of the processes or benefits, and this art has been practiced for thousands of years [7–9]. As at 2000–4000 BC, the Egyptians were producing alcoholic beverages [6]. According to records [10, 11], fermentation has been in practice also in Sudan, (1500 BC) and Mexico, (2000 BC). Despite advances in biotechnology and efforts towards industrialization of the traditional fermentations, uncontrolled traditional techniques/ kitchen technologies are still predominantly used for the processing of alkaline African

Modern food technology practices such as the use of good manufacturing practice (GMP) protocols, as well as new innovations like the use of starter cultures in controlled fermentations continue to play little or no role in the developing countries. The disposition to understanding traditional food processing is now beginning to gain some ground in developing countries. It is essential to recognize the significance of biotechnology-based innovations and applications in food processing in order to ensure quality and safety of products [12]. More recently, process techniques used in traditional fermented foods are being redefined and diversified through the use of molecular biology-based tools, enabling fermentation technology around these processes to evolve towards sustainable commercialization and industrialization. This lift from artisanal production has stimulated new interests in food research, such that today a lot of scientific works [13–26] have been devoted to these fermented foods. With modern biotechnology new and better methods for

Across cultures, a variety of traditional techniques are used for producing fermented foods and seasoning agents. The techniques differ based on microorganisms, raw material and fermentation conditions [27, 28]. Basically, processes involved in food product development by fermentation are of four types (**Figure 1**),

Alcoholic fermentation is mainly performed by yeasts leading to the production of ethanol. Products include wine, beer, other alcoholic beverages and bread. Lactic acid fermentation is driven by lactic acid bacteria (LAB), which produce organic acid and other compounds in various foods. Acetic acid fermentation is carried out by the acetic acid bacteria which convert alcohol to acetic acid under aerobic process as in vinegar. Alkaline fermentation usually takes place during the fermentation of

viz.: alcoholic, lactic acid, acetic acid and alkaline fermentation [6, 27, 29].

manufacturing practice and industrial and market development.

**16**

*An illustration of the various types of fermentations, based on microorganisms, fermentation condition and end product. Source: Anal [27].*



#### **Table 1.**

*The main classes of fermented foods based on the substrate from which they were derived.*

fish, legumes and other plant seeds (raw materials with high protein content, and in which principal metabolic processes center around protein degradation) to produce seasoning agents including *dawadawa* from Locust bean and *ugba* from oil bean and several related products.

Fermented foods can be classified in different ways based on the type of substrate, microorganisms involved in the fermentation and even the processing methods. Based on the substrate or raw material from which they are manufactured [30], foods derived by fermentation can be classified into five main categories namely: 1. Starchy foods such as root tubers (cassava), examples: *garri, akpu, lafun*, cereals (maize, sorghum, millet). 2. Alcoholic and non-alcoholic beverages (palm wine) *ngwo, nkwu enu, kunu-zaki*, 3. Animal protein based products (milk) example *nono*, warankasi 4. Fish/ sea food based foods examples *azu-okpo*, garum 5. Plant-seed and legume based products (seasoning agents), including *daddawa, iru* and *netetu* among others. **Table 1** presents the main classes of fermented foods based on the substrate from which they were derived.

#### **3. Diversity of alkaline fermented foods and seasoning agents**

Alkaline fermentation mainly relate to the fermentation of legumes (soy bean), protein rich oil seeds (African oil bean) and fish to produce condiments. During these processes, there is always an increase in pH up to 8 and above. The increase in pH has been attributed to the metabolic activities of the microbes that breakdown the protein of the raw material into peptides, amino acids and ammonia [2]. A diversity of alkaline fermented foods including seasoning agents are available world-wide, particularly in countries in Africa and Asia where these products are an integral part of the cultural diets of the native communities [2, 3, 12, 31]. They are

**19**

*Current Status of Alkaline Fermented Foods and Seasoning Agents of Africa*

**Raw material Product local name Distribution/**

*Chungkokjang or jeonkukjang* 

*Shoyu* Japan, Korea,

*Tempe* Indonesia (origin),

*Afitin/sonru/* Mali, Côte d'Ivoire

*Dawadawa/iru* West Africa

*Ogiri* West Africa/

*Ugba/Ukpaka* West Africa/

*Okpehe/okpeye/okpiye* West Africa/middle

*or cheonggukjang*

prepared from a wide range of raw materials including soybean, African locust bean and various species of fish [32]. Most of these are highly priced seasoning agents prepared by solid state fermentations in which *Bacillus* species are the key organisms. **Table 2** shows some common alkaline seasoning agents that are key players in traditional food systems across the world, particularly in Africa and Asia. Some

**country**

*Daddawa* West Africa, Nigeria A, B [15, 19] *Soy-dawadawa* Ghana A, B [3, 16, 20] *Kinema* India A, B [14, 41, 42] *Hawaijar* India A, B [43–45] *Aakhune* India A, B [27] *Bekang* India A, B [27] *Peruyaan* India A, B [27] *Tungrymbai* India A, B [27] *Thua-nao* Asia, Thailand A, B, C [27, 45–47] *Natto* Asia, Japan A–D [27, 48] *Douchi* China, Taiwan A, B [75, 76]

*Meju* Korea A, B [52] *Miso* Japan A–C [45, 53, 54]

*Tauco* Indonesia A, B [55]

The Netherlands, Japan, USA

*Soumbala* Burkina-Faso A, B, C [3, 60]

and Guinea, Nigeria (Benin)

*Netetu* Senegal A, B [62] *Kinda* Sierra Leone A, B [63]

> belt and southern Nigeria

*Kpaye/afiyo* Northern Nigeria A, B [64, 65]

Eastern Nigeria

Southern Nigeria

(Nigeria)

*Yandou* China A, B [45, 58, 59]

China

**State of development**

Korea A, B [27, 50, 51]

A, B [54]

A–D [45, 56, 57]

A, B [24, 27, 38, 61]

A, B [3, 24, 60,

A, B [4, 15, 24,

A–C [4, 67]

A–C [3, 22]

61]

66]

**References**

*DOI: http://dx.doi.org/10.5772/intechopen.87052*

Soy-bean (*Glycine max*)

African locust bean (*Parkia biglobosa*)

Mesquite (*Prosopis africana*)

Castor oil/fluted pumpkin/melon

African oil bean (*Pentaclethra macrophylla*)

### *Current Status of Alkaline Fermented Foods and Seasoning Agents of Africa DOI: http://dx.doi.org/10.5772/intechopen.87052*

*New Advances on Fermentation Processes*

Alcoholic and non-alcoholic

beverages

several related products.

Plant based alkaline product (seasoning agents)

*Sources: [4, 30–37].*

**Table 1.**

substrate from which they were derived.

fish, legumes and other plant seeds (raw materials with high protein content, and in which principal metabolic processes center around protein degradation) to produce seasoning agents including *dawadawa* from Locust bean and *ugba* from oil bean and

**Food group/class Substrate Derived product Country**

Animal-based product Milk *Nono* Nigeria

Fish/sea food product Fish *Azu-okpo* Nigeria

Refer to (**Table 2**)

*The main classes of fermented foods based on the substrate from which they were derived.*

Cereal *Burukutu/pito/otika* Nigeria Palm sap *Ngwo/nkwuenu* Nigeria Grape *Pique* Mexico Cane sugar *Sake* Japan

Beef tripe *Afo-nama* Nigeria Milk *Warankasi* Nigeria

Crab *Nshiko* Nigeria Cray fish/shrimp *Uponi/oporo* Nigeria Fish *Garum* Europe Fish *Suan yu* China Fish (herring) *Surstromming* Sweden

*Tape* Indonesia

Refer to (**Table 2**) Refer to

(**Table 2**)

Fermented foods can be classified in different ways based on the type of substrate, microorganisms involved in the fermentation and even the processing methods. Based on the substrate or raw material from which they are manufactured [30], foods derived by fermentation can be classified into five main categories namely: 1. Starchy foods such as root tubers (cassava), examples: *garri, akpu, lafun*, cereals (maize, sorghum, millet). 2. Alcoholic and non-alcoholic beverages (palm wine) *ngwo, nkwu enu, kunu-zaki*, 3. Animal protein based products (milk) example *nono*, warankasi 4. Fish/ sea food based foods examples *azu-okpo*, garum 5. Plant-seed and legume based products (seasoning agents), including *daddawa, iru* and *netetu* among others. **Table 1** presents the main classes of fermented foods based on the

**3. Diversity of alkaline fermented foods and seasoning agents**

Alkaline fermentation mainly relate to the fermentation of legumes (soy bean), protein rich oil seeds (African oil bean) and fish to produce condiments. During these processes, there is always an increase in pH up to 8 and above. The increase in pH has been attributed to the metabolic activities of the microbes that breakdown the protein of the raw material into peptides, amino acids and ammonia [2]. A diversity of alkaline fermented foods including seasoning agents are available world-wide, particularly in countries in Africa and Asia where these products are an integral part of the cultural diets of the native communities [2, 3, 12, 31]. They are

**18**

prepared from a wide range of raw materials including soybean, African locust bean and various species of fish [32]. Most of these are highly priced seasoning agents prepared by solid state fermentations in which *Bacillus* species are the key organisms. **Table 2** shows some common alkaline seasoning agents that are key players in traditional food systems across the world, particularly in Africa and Asia. Some



*State of development is based on published information. Product may not be in the market. Key: A: Microorganisms involved are known, B: Roles of organisms known or inferred, C: Starter Cultures have been developed or suggested, D: Pilot or improved technologies or industrial plant (s) available.*

#### **Table 2.**

*Some of the plant-based alkaline fermented seasoning agents.*

of these are described briefly to show state of the art and current application of modern technology (biotechnology) to the production processes.

Fermented condiments are cherished by consumers due to their peculiar organoleptic properties, nutritional and health significance as well as durability. The seasoning agents are characteristically used in small quantities to flavor traditional dishes, but their unique aroma eventually become central to the properties of those foods [9]. The quality of fermented foods is influenced by the starting raw material, microbiota as well as the processing methods [6]. The starting raw material for producing a particular seasoning can vary. For instance, *ogiri* is traditionally produced from any of three substrates namely: castor oil seeds, fluted pumpkin seeds (*Telfairia vulgaris*) and melon seeds. Given the diversity of raw materials from which comparable products are obtained, it is clear that the basis for uniformity in flavor characteristics relate considerably to the biochemical and physiological features of the microorganisms that drive the process. In different parts of the world, and even within the same region or country, the same fermented product may be known by different local names. For instance, in Nigeria *dawadawa /iru* is the traditional name for a fermented seasoning from African locust bean [33] while *netetu* is used in Senegal to refer to a food condiment from the same substrate [34] and *soumbala* is the traditional name used in Burkina-Faso [35].

#### **3.1 Traditional plant-based alkaline fermented seasoning agents**

Among the various substrates used for preparation of traditional fermented seasonings, soy beans is the most popular because of its wide spread distribution across the globe and importance as a rich source of plant protein [36]. In East and Southeast Asia and in West Africa, a wide range of alkaline fermented seasonings are produced from soy bean [27]. These include West African *dawadawa,* Japanese *natto* and Thai *thua nao*. Soy bean can be fermented by either bacteria or fungi. For bacteria-based soy bean products, *Bacillus* species (predominantly *B. subtilis*) are the predominant microorganisms. Fungi-based soy bean products are produced

**21**

**Figure 2.**

*Flow chart for the traditional method of producing dawadawa.*

*Current Status of Alkaline Fermented Foods and Seasoning Agents of Africa*

(*Okpeye/ okpehe/ kpaye/ afiyo*) and African oil bean (*ugba*).

using filamentous mold (Mostly *Aspergillus, Mucor, Rhizopus*) [27]. The other common substrates used to prepare alkaline fermented products in Africa include African locust bean (*dawadawa, iru, kinda, soumbala)*, African mesquite seeds

Apart from these popular legumes and oil seeds, other less popular and less utilized legumes and vegetables are also used for production of alkaline condiments in Africa. These include *Albizia saman* seeds for production of aisa [22], cotton seeds (*Gossypium hirsutum*) for used production of *owoh* [2] and *Hibiscus sabdariffa*

*Dawadawa* is probably the most popular and commercially successful traditional seasoning agent in West and Central African Savannah where it is known by different ethnic names [38, 39]. *Dawadawa* is processed from the solid substrate fermentation of cotyledons of locust bean (*Parkia biglobosa*). It is widely consumed as a food seasoning in the Northern and some part of Southern Nigeria [3, 15]. The traditional process may vary slightly depending on the processor and locality. In perhaps the most popular process (**Figure 2**) the basic steps include boiling of

*DOI: http://dx.doi.org/10.5772/intechopen.87052*

for production of bikalga [37].

*3.1.1 Dawadawa*

*Current Status of Alkaline Fermented Foods and Seasoning Agents of Africa DOI: http://dx.doi.org/10.5772/intechopen.87052*

using filamentous mold (Mostly *Aspergillus, Mucor, Rhizopus*) [27]. The other common substrates used to prepare alkaline fermented products in Africa include African locust bean (*dawadawa, iru, kinda, soumbala)*, African mesquite seeds (*Okpeye/ okpehe/ kpaye/ afiyo*) and African oil bean (*ugba*).

Apart from these popular legumes and oil seeds, other less popular and less utilized legumes and vegetables are also used for production of alkaline condiments in Africa. These include *Albizia saman* seeds for production of aisa [22], cotton seeds (*Gossypium hirsutum*) for used production of *owoh* [2] and *Hibiscus sabdariffa* for production of bikalga [37].

## *3.1.1 Dawadawa*

*New Advances on Fermentation Processes*

Roselle (*Hibiscus sabdariffa*)

*Cathormion altissimum*

Saman tree (*Albizia saman*)

Cotton seed (*Gossypium hirsitium*)

**Table 2.**

**Raw material Product local name Distribution/**

of these are described briefly to show state of the art and current application of

*Oso* West Africa/

leptic properties, nutritional and health significance as well as durability. The seasoning agents are characteristically used in small quantities to flavor traditional dishes, but their unique aroma eventually become central to the properties of those foods [9]. The quality of fermented foods is influenced by the starting raw material, microbiota as well as the processing methods [6]. The starting raw material for producing a particular seasoning can vary. For instance, *ogiri* is traditionally produced from any of three substrates namely: castor oil seeds, fluted pumpkin seeds (*Telfairia vulgaris*) and melon seeds. Given the diversity of raw materials from which comparable products are obtained, it is clear that the basis for uniformity in flavor characteristics relate considerably to the biochemical and physiological features of the microorganisms that drive the process. In different parts of the world, and even within the same region or country, the same fermented product may be known by different local names. For instance, in Nigeria *dawadawa /iru* is the traditional name for a fermented seasoning from African locust bean [33] while *netetu* is used in Senegal to refer to a food condiment from the same substrate [34]

Fermented condiments are cherished by consumers due to their peculiar organo-

**country**

Nigeria

African yam bean *Owoh* Nigeria A, B [21, 71, 72]

Leaves of Cassia *Kawal* Sudan A, B [45, 74] *State of development is based on published information. Product may not be in the market. Key: A: Microorganisms involved are known, B: Roles of organisms known or inferred, C: Starter Cultures have been developed or suggested,* 

*Aisa* Nigeria A, B [21]

*Owoh* Nigeria A, B [2, 73]

*Bikalga* Burkina-Faso A–C [68, 79] *Daton* Mali [68] *Furandu* Sudan [2] *Mbuja* Cameroon [2]

**State of development**

A, B [69, 70]

**References**

modern technology (biotechnology) to the production processes.

*D: Pilot or improved technologies or industrial plant (s) available.*

*Some of the plant-based alkaline fermented seasoning agents.*

and *soumbala* is the traditional name used in Burkina-Faso [35].

**3.1 Traditional plant-based alkaline fermented seasoning agents**

Among the various substrates used for preparation of traditional fermented seasonings, soy beans is the most popular because of its wide spread distribution across the globe and importance as a rich source of plant protein [36]. In East and Southeast Asia and in West Africa, a wide range of alkaline fermented seasonings are produced from soy bean [27]. These include West African *dawadawa,* Japanese *natto* and Thai *thua nao*. Soy bean can be fermented by either bacteria or fungi. For bacteria-based soy bean products, *Bacillus* species (predominantly *B. subtilis*) are the predominant microorganisms. Fungi-based soy bean products are produced

**20**

*Dawadawa* is probably the most popular and commercially successful traditional seasoning agent in West and Central African Savannah where it is known by different ethnic names [38, 39]. *Dawadawa* is processed from the solid substrate fermentation of cotyledons of locust bean (*Parkia biglobosa*). It is widely consumed as a food seasoning in the Northern and some part of Southern Nigeria [3, 15]. The traditional process may vary slightly depending on the processor and locality. In perhaps the most popular process (**Figure 2**) the basic steps include boiling of

**Figure 2.** *Flow chart for the traditional method of producing dawadawa.*

the locust bean seeds for 12–24 h, followed by manual de-hulling to remove the seed coat. The de-hulled cotyledons are collected and washed thoroughly and then boiled again for 1 h. The cotyledons are placed in jute bags or wrapped with banana leaves and allowed to ferment for 2–4 days at ambient temperature. During fermentation, the pH increases from near neutral to 8.1 or higher due to the breakdown of protein to amino acids and ammonia. As with other traditional processes, inoculation is usually fortuitous from production environment and equipment used or (rarely by back slopping). Microorganisms that drive the process are predominantly species of *Bacillus* [14, 40]. Other associated organisms include *Staphylococcus* [41], but the roles of these minor populations are contentious. At the end the product is sticky, with pungent odor and covered with mucilaginous grayish layer.

*Dawadawa* is the most scientifically studied traditional seasoning in West Africa. Several studies designed to improve the traditional process of have been published [41, 42]. **Figure 3** shows a modified procedure for *dawadawa* production [43]. Although, many African alkaline seasoning agents are still produced by the old-aged traditional cottage and kitchen processes, the preparation of some condiments like *dawadawa* has achieved pilot commercial status and is now considerably carried out on large scale by

**23**

*Current Status of Alkaline Fermented Foods and Seasoning Agents of Africa*

ment of flavors from legumes hydrolysis for bouillon-type products [44].

entrepreneurs [29]. In Nigeria and some other parts of West Africa, *dawadawa* cubes are available in the markets [43] with improved quality, durability and packaging. These are produced using reasonably reproducible protocol and are marketed under various brand names. However, the most significant achievement towards improving the traditional fermentation technology is that the mechanism of flavor production during the fermentation, as well as flavor components generated in *dawadawa* have been studied by international food manufacturers and used as basis for the develop-

*Soumbala* is a traditional condiment popular in Burkina Faso and other countries in West and Central Africa. It is also known by different names by different local communities [45]. Similar to *dawadawa*, it is prepared by solid state alkaline fermentation of African locust beans. It contributes significantly to protein nutrition of the consumers. The traditional process for preparing *soumbala* is uncontrolled and similar to *dawadawa* with minor variations based on ethnic preferences. The principal microorganisms involved in the fermentation of *soumbala* are *Bacillus* spp. [34]. The ability of *Bacillus* species involved in *soumbala* fermentation to inhibit undesirable bacteria including *Bacillus cereus* and *E. coli* has been reported [46–48].

*Okpeye*, much like *dawadawa* is a traditional seasoning produced by solid substrate alkaline fermentation of *Prosopis africana* (African mesquite) seeds. *P. africana* grows across the African Savannah and rain forest regions, but is mostly used as source of seasoning in the middle belt and parts of the Southeastern Nigeria [3]. Like *dawadawa*, the household technology used for producing *okpeye* can also vary between cultures. Perhaps, the most common procedure for preparation of *okpeye*, as practiced in parts of Southeastern Nigeria is as described (**Figure 4)** [9]. The process involves boiling of the mesquite seeds for 12–24 h to cook the seeds, soften the seed coat and ease the de-hulling process. This is followed by de-hulling in a very laborious manual process. The cotyledons are washed thoroughly, drained and reheated (dry heat) in a pot lined with the leaves of *Alchornea cordifolia* popularly known as (*akwukwo okpeye*) by the native people. Other leaves such as banana leaves may be used when the conventional leaves are unavailable. The cotyledons are spread to a few cm depth in a shallow raffia basket already lined with leaves of *Alchornea cordifolia*, covered with more leaves and weighted with pebbles. This solid substrate fermentation arrangement is then placed outside under the sun in the day time and inside the house in the night (avoiding precipitation and moisture for the duration of the process). Fermentation proceeds for 4 days at uncontrolled temperature which varies from less than 30°C at night to over 37°C in the afternoons during very sunny days. At the end of this stage the fermented cotyledons now dark brown in color with strong ammonia-like smell are ground into a smooth paste and molded into different shapes and sizes. At this moment the product may be used but for more desirable quality, it is usually sun dried for a variable length of time at the end of which the product becomes hard and black with a more mellow and preferable aroma. The dried condiment is resistant to spoilage by microorganisms and has a very long shelf life with occasional re-drying under the sun [3]. **Figure 5** shows the stages in the traditional process of *okpeye* production. During the natural process the pH increases from an initial of 6.0–6.2 in the boiled unfermented substrate to 8.0–8.8 (sometimes pH of 9.0–9.2 may be achieved) in the fermented product [49]. In our laboratory a diversity of microorganisms were established to be involved in

*DOI: http://dx.doi.org/10.5772/intechopen.87052*

*3.1.2 Soumbala*

*3.1.3 Okpeye*

**Figure 3.** *Flow chart for the modern production of dawadawa. Source: [15, 31, 38].*

#### *Current Status of Alkaline Fermented Foods and Seasoning Agents of Africa DOI: http://dx.doi.org/10.5772/intechopen.87052*

entrepreneurs [29]. In Nigeria and some other parts of West Africa, *dawadawa* cubes are available in the markets [43] with improved quality, durability and packaging. These are produced using reasonably reproducible protocol and are marketed under various brand names. However, the most significant achievement towards improving the traditional fermentation technology is that the mechanism of flavor production during the fermentation, as well as flavor components generated in *dawadawa* have been studied by international food manufacturers and used as basis for the development of flavors from legumes hydrolysis for bouillon-type products [44].
