The main classes of fermented foods based on the substrate from which they were derived.
Fermented foods and seasoning agents play central roles in the food and nutrition security of nations across the world, but particularly so in Africa, Asia, South America and Oceania. As several people across the world gravitate back to “eating natural,” there is a new emphasis on these fermented foods and seasoning agents which are also critical cultural foods in countries and societies where they are important. The result is the growth in demand for these products beyond what the traditional kitchen technologies is able to cope with. In Africa, many of the seasoning agents are products of alkaline fermentation of legume seeds, pulses and in some cases animal proteins and sea foods. 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. 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 development and the need to grow this value chain that has helped to sustain societies through ages.
- alkaline fermentation
- African seasoning agents
- fermented foods
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 . A distinct group of fermented foods is the traditional alkaline fermented products often used as food condiments/ seasoning agents . 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 . 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 . 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 . 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, 8, 9]. As at 2000–4000 BC, the Egyptians were producing alcoholic beverages . 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 . 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, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 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 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
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 , foods derived by fermentation can be classified into five main categories namely: 1. Starchy foods such as root tubers (cassava), examples:
|Food group/class||Substrate||Derived product||Country|
|Starchy foods||Root tubers|
|South Africa, Kenya|
|Alcoholic and non-alcoholic beverages||Cereal||Nigeria|
|Fish/sea food product||Fish||Nigeria|
|Plant based alkaline product (seasoning agents)||Refer to (Table 2)||Refer to (Table 2)||Refer to (Table 2)|
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 . 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 prepared from a wide range of raw materials including soybean, African locust bean and various species of fish . Most of these are highly priced seasoning agents prepared by solid state fermentations in which
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 . The quality of fermented foods is influenced by the starting raw material, microbiota as well as the processing methods . The starting raw material for producing a particular seasoning can vary. For instance,
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 . In East and Southeast Asia and in West Africa, a wide range of alkaline fermented seasonings are produced from soy bean . These include West African
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
The basic procedures (Figure 6
Microbiological and biochemical changes that take place during the traditional process have been studied extensively [50, 51]. A diverse group of microorganisms were reported to participate in the traditional fermentation of African oil bean, with
3.2 Less common legume-based alkaline fermented seasoning agents of Africa
3.3 Fish-based fermented products used as condiment in Africa
Like oil seeds, fermentation of fish is an essential part of socio-economic life of many communities in Africa particularly in Ghana, Egypt and Nigeria. Owing to the rapid deterioration of fish, fermentation offers an easy and cost effective way of preserving it. In the tropical countries fish fermentation usually involves the use of high concentration of salt combined with drying [53, 54]. Duration of fermentation is from a few days to weeks. Fish can be fermented whole or in parts. As in many traditional processes, fermentation of fish is carried out on small scale in homes [55, 56]. As with other traditional processes, uncontrolled nature and lack of hygiene practices are the major challenges to product quality and safety. The most popular fermented fish products used as condiments in Africa include
|Raw material||Product local name||Distribution/country||State of development||References|
|Soy-bean (||West Africa, Nigeria||A, B||[15, 19]|
|Ghana||A, B||[3, 16, 20]|
|India||A, B||[14, 41, 42]|
|India||A, B||[43, 44, 45]|
|Asia, Thailand||A, B, C||[27, 45, 46, 47]|
|Asia, Japan||A–D||[27, 48]|
|China, Taiwan||A, B||[75, 76]|
|Korea||A, B||[27, 50, 51]|
|Japan||A–C||[45, 53, 54]|
|Japan, Korea, China||A, B|||
|Indonesia (origin), The Netherlands, Japan, USA||A–D||[45, 56, 57]|
|China||A, B||[45, 58, 59]|
|African locust bean (||Burkina-Faso||A, B, C||[3, 60]|
|Mali, Côte d’Ivoire and Guinea, Nigeria (Benin)||A, B||[24, 27, 38, 61]|
|Sierra Leone||A, B|||
|West Africa (Nigeria)||A, B||[3, 24, 60, 61]|
|Mesquite (||West Africa/middle belt and southern Nigeria||A–C||[3, 22]|
|Northern Nigeria||A, B||[64, 65]|
|Castor oil/fluted pumpkin/melon||West Africa/Eastern Nigeria||A, B||[4, 15, 24, 66]|
|African oil bean (||West Africa/Southern Nigeria||A–C||[4, 67]|
|Roselle (||Burkina-Faso||A–C||[68, 79]|
|West Africa/Nigeria||A, B||[69, 70]|
|Saman tree (||Nigeria||A, B|||
|African yam bean||Nigeria||A, B||[21, 71, 72]|
|Cotton seed (||Nigeria||A, B||[2, 73]|
|Leaves of Cassia||Sudan||A, B||[45, 74]|
|Substrate||Product local name||Nature of product||Region/country||Microorganism||Reference|
|Cassava fish (||Condiment||West Africa|||
|Cat fish, barracuda, sea bream and African jack mackerel (||Condiment||West Africa (Ghana)|||
|Sauce||Egypt||Not known||[37, 95]|
|Shrimp, salt||Condiment||Malaysia||[45, 96]|
|Fish shrimp||Condiment||Indonesia||[37, 45, 97]|
|Marine fish salt, sugar||Condiment||Thailand, Malaysia||[37, 45, 98]|
|Finger size fish (||Condiment||India||[45, 99]|
|Sardine, salt||Condiment||Korea||[45, 100]|
|Shell fish||Condiment||Korea||[45, 101]|
|Marine fish||Condiment||Vietnam||[45, 102]|
Lanhouin is a traditional fermented salted fish condiment in West Africa, prepared from whole cassava fish (
4. Significance of food fermentation to rural communities and economies
The significance of fermented foods including seasoning agents in human nutrition, particularly among rural populations is now better appreciated. As a result research efforts are being intensified towards better understanding of the processes as well as to achieve commercialization of these foods. Fermented foods including those derived from alkaline fermentation are critical components of the human diets world-wide. Currently, it is estimated that fermentation derived foods, beverages and condiments contributes about a third of the human diets and food supply world-wide . These foods are particularly important in the cultures and food ecology of the developing nations such as Africa where thy have been reported to contribute more than half the calorie, ensuring the food security of millions . In the recent times, the awareness of the nutritional values and health benefits associated with eating fermented products has made them indispensable as part of food system and has also led to their being classified as functional foods.
In some African countries especially Nigeria, fermented foods are valuable in the nutrition of infants and school-age children. In the rural communities,
5. Traditional fermentation techniques
The techniques of traditional fermentation can be solid-state or submerged culture. In solid state fermentation, the microorganisms grow on solid substrate containing little or no free moisture, but enough to sustain metabolic activity of the organisms. This technique is used in the production of all the alkaline fermented seasoning agents discussed earlier. Submerged fermentation is performed on a liquid substrate or a solid substrate immersed in a solution to form a suspension or slurry. These types of fermentations are seen in most commercial processes such as those employed for the production of alcoholic beverages and several other high-volume products.
5.1 Impact of process techniques on food quality
In the past, fermented foods were important only in the regions or places of manufacture. However, due to increasing demand, urbanization and industrialization, some of the fermented products such as soy sauce, and Japanese natto are becoming globally popular . The challenge though is that the majority of the indigenous fermented foods and condiments are manufactured under conditions devoid of good manufacturing practices (GMPs) and good hygiene practices (GHPs) . Often, hazard analysis and critical control point principles (HACCPs) are not observed during their production and unit operations are not clearly defined. This is inconsistent with modern food practices and may hinder the adoption of such products into the international markets . Obviously, the uncontrolled nature of process techniques of traditional fermentation can have fundamental impact on the quality and safety of products. In the traditional setting, fermentation associated variables such as pH, DO, temperature, inoculum and moisture are not regulated. The variation in the fermentation conditions has frequently affected product quality, resulting in products that are non-uniform in quality between successive batches. Likewise, differences in processing techniques adopted by various processors which depend so much on personal knowledge, experience and expertise of the food handler and processor can also cause variation in product quality. Besides, the equipment used in the processing of traditional alkaline fermented seasonings such as fresh leaves, jute bag, local basket and calabash are substandard and they fall short of standard food hygiene protocol. Product consistency and safety of traditional fermented foods often arise fortuitously, from the physiological pressures imposed by the microbial selection rather than by processor actions.
In any food industry, maintaining proper hygiene in the production environment should be priority . Although traditional fermentations often achieved the desired products, there is need to integrate modern GMPs in the production of these valuable constituents of traditional diets. Another significant challenge in traditional fermentation that can lead to poor and inconsistent product quality is the participation of undesirable microbial strains in the process . Most traditional alkaline fermentations rely on chance inoculation that encourage the participation of several species of microorganisms, including desirable and undesirable strains as against modern industrial technologies that make use of a single or defined selected strains (starter culture) to effect the desired change in the substrate. Although substrate modification and environmental condition may be tailored to favor the growth of the desired organisms, total reliance on process conditions to guarantee product/consumer safety may not always result in desirable outcomes. Besides, the contribution of the transient populations to the final product flavor and quality remain unknown. It is necessary therefore to migrate these traditional processes to modern, biotechnology-based food processing to eliminate process failures, some of which can result in consumer risks. Consumer safety and product quality can be best ensured by strict compliance with GMP.
6. Modern approach to food fermentation in Africa
In recent times, scientific knowledge and modern food processing technologies have found application in food fermentation particularly in Asia and South America. The result is that many traditional kitchen technologies used in the manufacturing of fermented foods in the past are now modified . The same may not be said (to the same degree) of traditional fermentation in Africa, where products are still mostly produced through kitchen technologies and village art that rely on illiterate processors. However, gradually the technology of alkaline fermented foods and products derived from other fermentations is evolving to a better and more commercial status. Progressively, traditional fermentation processes are being refined and diversified through the application of molecular biology and microbial technology (MT) such as the use of improved raw materials, starter/protective culture, process optimization/ control including the use of modern packaging. This shift from artisanal production to scientific industrial one has generated new areas of study for industrialists and food scientists and new small scale industries. Innovations and recent developments in the production of alkaline fermented foods in Africa and other regions of the world will be approached at four levels namely: Raw material development, the use of starter culture, modified fermentation processes (process optimization), and product presentation (packaging).
6.1 Raw material development
High quality raw materials should be sourced and tested in order to select the more appropriate variety for use in fermentation. Agricultural procedures that encourage increased production of the improved varieties should be adopted. The use of improved and homogenous substrate for production of fermented foods will go a long way in solving the problem of product variability. The various raw materials (legumes and oil seeds) used for producing alkaline fermented foods are seasonal crops and are not readily available round the year. In order to overcome the current challenges of periodic or non-availability of raw materials, the use of irregularly available raw materials are being replaced wholly or partially with more abundant substrates in the production of various fermented products [3, 19]. In instances, the conventional substrate for production of ogiri an African alkaline fermented seasoning agent is castor oil seed . However, when the main substrate is unavailable, alternative materials such as melon seed and fluted pumpkin seeds are used for the production . Similarly, a related food condiment
6.2 The use of starter culture
Literature on the use of starter cultures for the production of alkaline fermented foods including seasoning agents abound (Table 4). Modern researches on fermented foods have begun to adopt new approaches that focus on understanding the profile and the role of associated microorganisms in alkaline fermentations. Food researchers recognize that metabolic activities of microorganisms involved in a process have considerable impact on quality attributes of the final product such as color, flavor, texture and aroma as well as nutritional quality. Equipped with this knowledge, approaches used for characterizing the microorganisms in fermented foods have evolved to a better status. Many different techniques have been adopted to study the diversity of micro flora of fermented foods and their possible roles. This may be grouped into two: cultural/physiological methods and molecular methods . Molecular techniques are of great importance in studying the microbial profiles, succession and functionality in traditional fermented foods. PCR-based methods and gene sequencing are now used for proper characterization of micro-biota including pathogens in fermented foods. Functional genomics is a useful tool in improving traditional process as this enables comparisons of traits of microorganisms involve in food fermentation and enables selection of organisms with desirable traits as potential starter cultures.
|[85, 87, 88]|
“Omics” is the acronym that has arisen from the study of functional genomics and comprises transcriptomics, proteomics and metabolomics. The introduction of “Omics” technologies offer better and clearer understanding of microbial populations in food processes and provide good opportunity for process standardization. These have been applied in the study of some traditional fermented foods such as
Recent developments allow the establishment of starters, resulting in the evolution of kitchen technology to more optimized/controlled fermentation. The microorganisms used as starter cultures in food processing are selected based on food substrate, with the objective of achieving objective and reproducible bio-modification.
In the efforts towards commercialization and upgrading of African alkaline fermented foods to industrial level, different species of microorganism have been studied and screened Table 3 . Pure cultures of
Besides, other bacteria such as lactic acid bacteria (LAB) have also been used as starter cultures for fermented foods including fermented fish [88, 89, 90, 91]. A combination of
Apart from bacteria, fungal starter cultures have been applied in the production of fermented foods. A combination of
6.3 Modified fermentation process (process optimization and control)
The uncontrolled nature of traditional fermentations is a major hindrance to the scaling up of indigenous food fermentations . Optimization may only be possible when the roles of process variables such as duration of fermentation pH, temperature, inoculum-substrate ratio, DO and mass transfer and pretreatment are understood and controlled [16, 22, 35, 42]. An improved method of producing an African fermented condiment (Dawadawa) from locust beans has been reported to reduce fermentation time and cost of energy . Also, in Burkina-Faso, a novel de-hulling machine introduced in the production of
In Uganda, pasteurization and refrigeration were used to increase the shelf life and safety of
6.4 Product presentation (packaging)
Packaging is an integral part of GMPs in foods. It provides environmental condition for storage, handling and long shelf life of product. It also minimizes post-process contamination and protects against microbial spoilage including undesirable change in sensory properties as well as consumer abuse. The shelf life of processed foods can be extended by aseptic and adequate packaging. Inadequate packaging and poor presentation of product are among the challenges mitigating the global development and consumer appeal of fermented products in Africa and other developing regions . Unlike modern food industries that use attractive and esthetic packaging that increases consumer appeal, all sorts of wrapping materials are used for packaging traditional fermented products in Africa . On account of this, indigenous fermented foods are often considered as food for the poor . The adoption of modern esthetic packaging and adequate presentation are crucial steps to overcome the challenges of kitchen technology and also for commercialization and industrialization of fermented foods and condiments. These will help to minimize the problems of post process contamination and increase consumer confidence.
The application of these basic food-control strategies in the production of fermented foods will move these products beyond the local markets. Besides the challenges of unattractive packaging, some local fermented products such as dawadawa and okpeye are not packaged at all. These are displayed at points of sale often in open non-sterile bowls and local baskets which may lead to post-production contamination .
7. Conclusion and the way forward
Although, the economic and food security importance of African fermented foods and seasonings remain outstanding, their continued availability in the near future in a rapidly urbanized and global setting cannot be guaranteed on the basis of the present household technologies and practices. Today, with surge in the demand for “natural” foods, there is resurgence in demand across board for traditional foods which have also somehow become synonymous with the natural foods. The surge in demand for these traditional fermented products is not matched by supply and the trend can only get worse on the basis of kitchen technologies and traditional raw materials supply. Therefore, if we are to continue to enjoy these valuable components of our cultural diets, there has to be a way to manufacture those using sustainable modern technologies and GMPs. It is a challenge to industrialists, food scientists and researchers to ensure that knowledge generated through research are used to bring new ideas and innovations in the area of food fermentation and value chain. It has been observed that much of the research findings from scientists, particularly in the developing countries, end up in the journals and never make it to the market. There is an urgent need to address and bridge this research-to-market gap. It hoped that through research innovations, many fermented foods can be developed on the basis of good manufacturing practices (GMPs) to be able to achieve sustainable commercial marketability in the coming years. Currently, the disposition to understand traditional fermentation processes and their applications for industrialization is gaining ground in Africa and other developing regions. It is essential to recognize the critical role of microbial technology and significance of molecular biology-based applications in food processing in order to ensure quality and safety.
Recent understanding in the methods of processing fermented foods through application of scientific information has helped to improve quality of traditional foods in many ways. Microbial technology has played a key role in this aspect, being helpful for production of functional foods, bio-preservation and sensory improvement of fermented foods. With the application of sophisticated technologies including genomics and proteomics, commercialization and industrialization of fermented foods look promising. Figure 11 illustrates prospects of biotechnology in commercialization and industrialization of fermentation process. Future research will have to look at the use of improved raw materials as fermentation substrates, development and use of standard inoculums (starter cultures), and application of process control and defined unit operation, use of GMP and HACCP protocols by food processors, and use of adequate and esthetic packaging materials. These will eliminate challenges associated with food safety, achieve uniformity and reproducibility in products, enhance consumer confidence and increase product marketability across borders. A major breakthrough in the years ahead will target the evolution of viable small and medium fermentation enterprises around traditional alkaline fermented foods and other related products in Africa and other parts of the world.