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13. Amorphophallus: Technological Interventions
Ramesh C. Ray1 and Sudhanshu S. Behera2 3
1ICAR ― Central Tuber Crops Research Institute (Regional Centre), Bhubaneswar, India
2 Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India
3 Department of Biotechnology, College of Engineering and Technology (BPUT), Bhubaneswar, India
13.1 Introduction
The plant genus Amorphophallus (commonly known as the Elephant Foot Yams, EFY), is a tuberous root crop, which belongs to the Araceae (aroidae) family of the Order Nudiflorae of Monocotyledenae and is estimated to encompass some 170 species (Mukherjee et al., 2014; Sedayu et al., 2010). These species are distributed in tropical Africa, India, the Indo-Malayan archipelago, Melanesia and Australia; however, none are found in the neo-tropics. They mostly grow in secondary forests or disturbed clearings in primary forests and forest margins. Considering the extent of endemism and the number of species recorded (in the genus) from the region, the Indo-Malayan may be considered as the centre of origin of the crop (Mukherjee et al., 2014).
Amorphophallus species are herbs with an underground storage organ called tubers. One single leaf emerges from the tuber, consisting of a vertical spotted petiole and a horizontal leaf-blade (lamina) like an umbrella (Figure 13.1). The leaf blade growing horizontally is dissected into a few or numerous small leaflets. Once plants are mature, an inflorescence may develop. The inflorescence may replace the leaf in one season, or develop alongside it. As a characteristic typical to the family Araceae, the inflorescence consists of a foliar organ, the spathe, which usually envelops a stalk-like organ, the spadix. The elongated and elaborate spadix is how the genus got its name, Amorphophallus.
Figure 13.1 Structure of Amorphophallus paeoniifolius (var. Gajendra) plant (a) with tuber insert (b) of two years old.
EFY (also called Konjac in China), is grown as a cash crop due to its high production potential and popularity as a vegetable in many Asian and African countries (Nedunchezhiyan et al., 2011). China and India are the major EFY producing countries in Asia. Several value-added products and indigenous medicines are also prepared from its tubers (Misra et al., 2003; Nedunchezhiyan et al., 2011). In this chapter, the various aspects related to nutritional and anti-nutritional factors, traditional processes for the removal of anti-nutrients, processing for flour, starch and resistant starch from EFY, are discussed. Also, industrial utilization of Amorphophallus konjac into konjac flour and gum, glucomannan (KGM) and its applications as a food and pharmaceutical supplements are reviewed.
13.2 Habit, Habitat and Distribution
Amorphophallus is a perennial tuberous herb with a highly compressed stem called a corm, an underground stem modification, serving the function of storage. It is persistent and continues to put forth shoot growth annually producing new corms, cormlets or side tubers. The aerial portion of the plant is represented by a single leaf, which has a long cylindrical petiole, the “culm” or pseudo-stem and a partite lamina. The petiole is adorned with several stripes and markings of different hues and shapes, and the nature of spathe, spadix (inserted or excerted) female, neutor and male flowers and their distribution on the peduncle (sparsely or closely arranged), tuber characteristics and the features of the sterile appendage, the nature of the partite “leaf lets”, their venation and presence or absence of marking or “bulbils” at their inter-junction, are some of the morphological characters that help in species characterization and identification. The inflorescence character is the most important distinguishing feature of the species. Species characterization helps us to understand the habit along with geo-climatic distribution of individual species.
The genus Amorphophallus with about 170 species primarily occurs in tropical Asia and Africa (Bogner et al., 1985; Hay, 1998). Ten species are endemic to India, such as A. carnosus, A. longistylus and A. oncophyllus to the Andaman Islands, A. arunachalensis and A. bognerianus to Arunachal Pradesh, A. mysorensis to Karnataka, A. longicon-nectivus to Madhya Pradesh, and A. bonaccordensis, A. nicolsonianus and A. smithso-nianus to Kerala (Mukherjee et al., 2014). A. paeoniifolius, A. hirsutus, A. brooksi, A. jijas and A. prainii are species that occur in Sumatra. A. konjac is abundantly found in Korea and China. The tall type with largest inflorescence (10 ft height) A. titanium occurs in Indonesia. A. konjac and A. jaijas (A. brooksi) also have tall spadices (4-10 ft height). A. bulbifer, A. kachinensis, A. hirsutus, A.nepalansis, A. paeoniifolius and A. sylvaticus are the species with a wide distribution in India, Myanmar, Thailand, Laos, China, Sumatra, Bhutan, Nepal, Srilanka and the Pacific Islands. The edible species are A. paeoniifolius (Dennst) Nicols var. campanulatus (Decne) Sivad, A. konjac K. Koch, A. mulleri Bl, and A. variabilis Bl. (Mukherjee et al., 2014).
13.3 Nutritional and Anti-nutritional Factors
The functional foods of natural origin, such as EFY and their derived nutritional products can act as functional ingredients and have a beneficial effect on human health (Reddy et al., 2014). EFY is considered to be a healthy low-fat food and a rich source of essential fatty acids (Omega-3 fatty acids), which are known to increase good cholesterol levels in the blood. Eating elephant yam helps to increase the estrogen levels in women’s bodies, thus helping to maintain the hormonal balance (Lenka and Nedunchezhiyan, 2014).