Ashutosh Upadhyay, National Institute of Food Technology, Entrepreneurship and Management (NIFTEM), Sonepat, India.
Bashira Wahab, Department of Food Science and Technology, Federal University of Agriculture, Abeokuta, Nigeria.
Preface
Tropical roots and tubers occupy an important place in the global commerce and economy of a number of countries and contribute significantly to sustainable development, income generation and food security, especially in the tropical regions. Researchers have demonstrated the importance of tropical roots and tubers to human health, contributing an important source of carbohydrates and other nutrients. The perishability and post-harvest losses are the major constraints in their utilization and availability, therefore they demand appropriate storage conditions at different stages and value addition. The objectives of this book are therefore to provide a range of options from production and processing to technological interventions in the field, in a comprehensive form at one place.
This book focuses on all the major aspects related to tropical roots and tubers. With a total of 18 chapters, contributed by various authors with diverse expertise and background in the field across the world, this book reviews and discusses important developments in production, processing and technological aspects. Individually, taro, cassava, sweet potato, yam and elephant foot yam are mainly discussed and covered. The chapters in the book describe and discuss taxonomy, anatomy, physiology, nutritional aspects, biochemical and molecular characterization, storage and commercialization aspects of tropical roots and tubers. Good agricultural practices and good manufacturing practices are also given special emphasis. The HACCP approach in controlling various food safety hazards in processing of tropical roots and tubers is also discussed. Technological interventions, brought out in different tropical roots and tubers, constitute a major focus and it is expected that this book will find a unique place and serve as a resource book on production, processing and technology.
This book is designed for students, academicians, industry professionals, researchers and other interested professionals working in the field/allied fields. A few books are available in this field but this book is designed in such a way that it will be different and unique, covering production, processing and technology of lesser publicized tropical roots and tubers. The text in the book is standard work and therefore can be used as a source of reference. Although best efforts have been made, the readers are the final judge.
Many individuals are acknowledged for their support during the conception and development of this book. Sincere thanks and gratitude are due to all the authors for their valuable contribution and co-operation during the review process. The valuable input from Wiley and the assistance by publishing and copy-editing departments is gratefully acknowledged. Sincere efforts have also been made to contact copyright holders. However, any suggestions or communications with respect to improving the quality of the book will be appreciated and the editors will be happy to make amendments in the future editions.
Harish K. Sharma Nicolas Y. Njintang Rekha S. Singhal Pragati Kaushal
1. Introduction to Tropical Roots and Tubers
Harish K. Sharma and Pragati Kaushal
Department of Food Engineering and Technology, Sant Longowal Institute of Engineering and Technology, Sangrur, India
1.1 Introduction
Roots and tubers are considered as the most important food crops after cereals. About 200 million farmers in developing countries use roots and tubers for food security and income (Castillo, 2011). The roots and tubers contribute significantly to sustainable development, income generation and food security, especially in the tropical regions. The origin of tropical roots and tubers along with their edible parts is presented in Table 1.1.
Table 1.1 Origin of tropical roots and tubers
Tropical roots and tubers | Origin | Edible part
Sweet potato | Central/South America | Root, leaves
Cassava | Tropical America | Root, leaves
Taro | Indo-Malayan | Corm, cormels, leaves and petioles
Yam | West Africa/Asia | Tuber | Elephant foot yam
Individually, cassava, potato, sweet potato and yam are considered the most important roots and tubers world-wide in terms of annual production. Cassava, sweet potato and potato are among the top ten food crops, being produced in developing countries. Therefore, tropical roots and tubers play a critical role in the global food system, particularly in the developing world (Amankwaah, 2012). The leaders, policy-makers and technocrats have yet to completely recognize the importance of tropical tubers and other traditional crops. Therefore, there is a need to focus more on tropical roots and tubers to place them equally in the line of other cash crops.
Tropical root and tubers are the most important source of carbohydrates and are considered staple foods in different parts of the tropical areas of the world. The carbohydrates are mainly starches, concentrated in the roots, tubers, corms and rhizomes. The main tropical roots and tubers consumed in different parts of the world are taro (Colocasia esculenta), yam (Dioscorea spp.), potato (Solanum tuberosum L.), sweet potato (Ipomoea batatas), cassava (Manihot esculenta) and elephant foot yam (Amorphophallus paeoniifolius). Yams are of Asian or African origin, taro is from the Indo Malayan region, probably originating in eastern India and Bangladesh, while sweet potato and cassava are of American origin (Table 1.1). Naturally suited to tropical agro-climatic conditions, they grow in abundance with little or no artificial input. Indeed, these plants are so proficient in supplying essential calories that they are considered a “subsistence crop” (www.fao.org). Because of their flexibility in cultivation under a mixed farming system, tropical roots and tubers can contribute to diversification, creation of new openings in food-chain supply and to meet global food security needs.
The perishability and post-harvest losses of tropical roots and tubers are the major constraints in their utilization and availability. The various simple, low-cost traditional methods are followed by farmers in different parts of the world to store different tropical roots and tubers. The requirements of storage at different stages during the post-harvest handling of tropical roots and tubers are presented in Figure 1.1. The perishable nature of roots and tubers demands appropriate storage conditions at different stages, starting with the farmers to their final utilization (consumers). Therefore, an urgent requirement exists to modernize the traditional methods of storage at different levels, depending upon the requirements of keeping quality.
Figure 1.1 Post-harvest handling stages in the storage of tropical roots and tubers.
The various interactive steps involved in post-harvest management of any tropical root or tuber, if not controlled properly, may result in losses. To prevent these losses, several modern techniques such as cold storage, freezing, chemical treatments and irradiation may be widely adopted. Roots and tubers not only enrich the diet of the people but are also considered to possess medicinal properties to cure various ailments. So the role of roots and tubers in functional products can also be investigated in the light of medicinal properties. An immense scope exists for commercial exploitation in food, feed and industrial sectors. Since tropical roots and tubers crops are vegetatively propagated and certification is not common, the occurrence of systemic diseases is another problematic area. Some of these root and tuber crops remain under-exploited and deserve considerably more research input for their commercialization.