Post harvest handling, processing and value addition ...

International Journal of Innovative Horticulture. 4(1):1-10, 2015 Review Article

Post harvest handling, processing and value addition of elephant foot yam — An overview Ramesh C. Ray

ICAR-Regional Centre, Central Tuber Crops Research Institute, Bhubaneswar 751 019, India

ABSTRACT Elephant foot yams (Amorphophallus spp.), a tropical tuberous root crop, is grown as vegetable crop in many Asian and African countries due to its high production potential and nutritional values. Apart from culinary purpose, the tubers are also used for developing many processed food products, nutraceutical foods like konjac glucomannan ( from Amorphophallus konjac) and several indigenous and traditional medicines. Like other vegetable crops, elephant foot yam tubers are subjected to several forms of post harvest losses such as weight loss, microbial infection and insect pest attack. In this article, the various issues related to post harvest handling, storage methods, diseases and pests, and traditional and novel value-added products (both as food and medicines) are briefly reviewed. Keywords: Amorphophallus spp., diseases and pests, elephant foot yam, konjac glucomannan root crop

INTRODUCTION Amorphophallus spp. (A. paenifolius, A. konjac, A. mulleri, A. riveiri, A. onchophyllus, A. yunnanensi, A. yuloensis, A. nanus and A. krausei, commonly known as Elephant Foot Yam (EFY) (Fig. 1) (also called Konjac in China), a tuberous root crop, is grown as a cash crop due to its high production potential, and popularly as a vegetable in many Asian and African countries (Nedunchezhiyan et al., 2002). China and India are the major EFY producing countries in Asia. Several value added food products and indigenous medicines are prepared from its tubers (Nedunchezhiyan et al., 2002; Misra et al., 2003). However, like any other vegetables under hot (40º±2ºC temperature in summer) and humid (85±5 Relative Humidity) conditions in tropics, EFYs are subjected to several forms of post harvest losses during har-

Fig. 1: A typical Amorphophallus (var. Gajendra) plant (A) with tuber (B)

vesting and subsequent handling during transportation and in market. In this review, the various issues related to post harvest handling, storage methods, diseases and pests, and traditional and novel value-added products (both as food and medicines) are discussed.

POST HARVEST HANDLING Harvesting and Storage Yellowing of leaves and drying of the plants indicate that the crop is ready for harvest. The tubers are harvested by digging, using the crowbars or spades. While harvesting, care is usually taken to avoid injury to the tubers. After harvesting, the adhering soil and roots are removed. The damaged tubers and those showing symptoms of rotting or infection are separated from the lot and disposed off immediately after the harvest. Curing and Grading of the Tubers Despite the best attention given during post harvest handling of EFYs, some wounding inevitably occurs as a result of detachment of the tubers from the culm. For successful storage and marketing, it is necessary to subject the harvested tubers to curing. Curing facilitates toughening of the skin and healing of the wounds thereby reducing the risk of post harvest infection and decay (Ray and Ravi, 2005). Curing induces suberization of exposed parenchyma cells

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and development of a wound periderm. Curing of EFYs is practiced in tropical countries by placing the tubers in open in shaded places at ambient temperature (28±20C) for 7-15 days till the wet soil adhering to the tubers gets dried and falls off (Misra et al., 2007). Following curing, the tubers are graded according to their size and shape. After grading, the tubers are transported to the market packed in bamboo baskets or in gunny bags with minimal physical injury.

Transportation of Tubers Adequately cured and graded tubers are carefully transported in gunny bags, palm baskets or paper cartoons (Misra et al., 2007). Air-tight containers are not usually used for transporting the tubers. Care is taken to maintain ventilation for the packed tubers. The tubers can also be kept in layers sandwiched with paddy straw/ dried palm / banana leaves to avoid bruises during transportation (Misra et al., 2007). Storage and Marketing of the Tubers The tubers of EFY can be stored safely for 3-4 months (Misra et al., 2005). The storage place should be well ventilated, cool and protected from rains. Research studies conducted at Regional Centre, Central Tuber Crops Research Institute (CTCRI), Bhubaneswar, India revealed that storing the tubers of EFY by spreading them closely in single layer with apical portion upwards and then covering with coarse dry sand followed by periodic removal of damaged tubers was the best method of storage (Misra et al., 2007). While placing on the racks, it is advisable to keep them separate not touching one another (Ravindran and George, 2008). Occasionally, the tubers should be examined and the damaged portions may be removed and the cut area may be treated with fungicide such as Mancozeb (Misra et al., 2003). The stored tubers start sprouting after 2-3 months of storage. Corms of A. paeoniifolius can loss as much as 25% of their initial weight in the first month of storage, but can be successfully stored at 10°C for several months. Alternatively, they may be left in the ground until required, with a little irrigation if necessary. In Japan corms of A. konjac that are to be replanted need to be protected in store from low winter temperatures because at temperatures of -5°C, the germination is severely affected (Long, 1998).

Technologies for Extending Shelf life of the Tubers In India Extending shelf life of EFY tubers can help the farmers to get higher price in off season. Though curing helps in extending shelf-life, it is inadequate since the interval between

harvesting and planting is very long. In some parts of Kerala and Andhra Pradesh, the farmers dip the tubers in the cow dung slurry followed by drying them in shade to extend their shelflife (Nanda, 2008). In Tripura, the tribal farmers developed a technology for extending shelf life of EFY tubers by converting them into cakes (Sankaran et al., 2008b). In this method, the EFY corms are cleaned and cut into pieces and boiled in bamboo shoot ash water. After decanting water, the cooked tubers are made into paste and dried in the form of cake. After drying, the cake is again cooked in the bamboo shoot ash water and sun-dried for two days. These cakes can be stored for 30-45 days without any quality deterioration. The bamboo shoots act as an alkali while the repeated boiling and drying removes the calcium oxalate crystals (Sankaran et al., 2008b).

In China The indigenous people of China practice several storage methods for extending shelf life of EFY tubers. The Dai people in the Yuvanyamg of Southern Yunnan and Bai people of Western Yunnan and people of Sichuan store the corms (A. nanus) in the cellars near their houses. The Jino people pile up corms (A. yuloencis and A. krausei) near the fireside. Several ethnic tribes in Yunnan cut the konjac corms into pieces and dry them in the sun before storage. This method enhances shelf life by 3-5 years. The indigenous people in Central Hunan also sometimes store EFY as the dry konjac cake (Long 1998). The indigenous people of Bai, Western Yunnan and people of Sichuan, China eliminate the corm skin and process the clean core corm into purified konjac tasty cakes and dried outside during the winter season (Long, 1998). Marketing of Tubers In India, the farmers sell their produce immediately after harvest to the traders. In some pockets of Andhra Pradesh, Kerala, Bihar and Uttar Pradesh, the produce is sold to the whole sellers through middlemen even before the harvest of the crop. In Andhra Pradesh, the farmers sell the harvested produce on weight basis, i.e. puttis (Putti: weight equivalent to 225 kg.). Healthy, cleaned corms free from any mechanical injury or blemishes are graded for maximum price. From Mumbai, the tubers are being exported to Middle East countries after packing them in standard containers (Murthy et al., 2008). For exporting the tubers for consumption purpose, the apical portions are removed and the skins are lightly peeled. Part of the produce is also sold as seed corms to other parts of the country (Misra et al., 2003).

Post harvest handling, processing and value addition of elephant foot yam — An overview

POST HARVEST DISEASES AND PESTS The incidence of post-harvest losses in EFY is very high at all stages from harvesting to consumption. The tubers are prone to several post harvest diseases due to their high moisture content and starch. The mechanical injury to the tubers during harvesting and transportation also predisposes them to various rotting fungi and bacteria. Besides damaging seed tubers, these pathogens also inhibit sprouting (Misra et al., 2007). On the other hand, relatively high rates of metabolic activity in the tubers results in the conversion of starch throughout the storage period thus lead to eventual weight loss. As a low-unit-cost produce, the use of effective sophisticated storage methods like refrigerated or controlled atmospheric storage, is hitherto precluded (Nanda, 2008). In general, the following factors act as predisposing factors for the post harvest losses the elephant foot yam tubers (Misra et al., 2007): ·

Pre- harvest infection in the field

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Injury to the tubers during harvest, transport and loading/ unloading

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Soil adhering to the tubers provide ready inoculums

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Nematode damage facilitates pathogen entry

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High moisture content of the tubers in storage promotes physiological and microbiological spoilage

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Poor storage methods

Major storage diseases and pests of elephant foot yam are described below:

Storage Rot The storage rot of the EFY tubers is the serious disease causing severe economic losses to the farmers of India and elsewhere (Misra et al., 2007). It is caused by the mechanical injuries of the tubers occurred during harvesting and subsequent transportation of the tubers to market or retailers. Infestation of the roots and tubers by root knot nematode (Meloidogyne incognita) also act as a predisposing factor for fungal infection. Misra et al., (2003) have identified six major pathogens that caused post harvest rotting of tubers. ·

Sclerotium rot caused by the Sclerotium rolfsii is the most common storage disease in EFY. This fungus slowly infects the entire tuber causing total loss.

·

Black rot or Botryodiplodia rot caused by Botrydiplodia theobromae is another serious disease of EFY. Initially, its infection is confined to the tuber surface, but over the period of time, the

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pathogen penetrates deep inside the tuber leading to rotting and blackening of tubers in patches. ·

Phytopthora rot caused by Phytopthora colocasiae is another severe disease of EFY but the damage is comparatively less than Sclerotum or Botryodiplodia rot.

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Fusarium rot (Fusarium spp.) and Rhizopus rot (Rhizopu spp.) also cause some damage during tuber in storage.

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Erwinia rot, caused by the bacterial pathogen, Erwinia carotovora has been found to cause serious damage to tubers when they are stored at higher temperature (< 400C) with poor ventilation. Tubers infected by E. carotovera turns watery and give a foul smell causing 80- 100% tuber loss.

To avoid storage rot, the tubers should be free from mechanical injury and pre-harvest infection. For this purpose, the infected tissues need to be removed with a sharp knife in such a way that no infected portion is left on the tubers. While removing the infected portion, even the healthy tissues adjourning the infected portions should be removed. The cut tubers should be immediately treated with a fungicide (i.e. Mancozeb @ 0.2%) and stored in single layer before planting. Storage of tubers of EFY in a cool and ventilated place followed by periodic removal of damaged tubers has been found effective in prevention of tuber rot. Murthy et al., (2008) reported that the pre-harvest application of carbendazim (0.1%) + streptomycin (150 ppm) at 30 days before harvest and treatment of the corms after the harvest with copper oxychloride (0.3%)+streptomycin (100 ppm) was found effective in checking the storage rot. Storing of the harvested tubers in the Zero Energy Cool Chamber in heaps was found to be effective in reducing weight loss and storage rots. Besides, the treatment of cut tuber pieces before planting with cow dung slurry mixed with Trichoderma @ 5 g. kg -1 ) or Mancozeb (0.2%) + Monocrotophos (0.1%) was also found effective against storage rot (Naskar, 2008). In Tripura and Meghalaya, the ash is spread on the cut end of EFY tubers to prevent the tuber rot and to increase the shelf- life of tubers. The ash acts as a deterrent and as disinfectant for the chewing and sucking type of the insects (Lal and Verma, 2006)

Scale Insects and Mealy Bugs Tubers of the EFY are severely infested by yam scale insect (Aspidiella hartii) in storage conditions if the tubers are stored more than three months, the citrus mealy bugs (Pseudococcus cryptus) infest the tubers. Though this infestation is superficial, it causes economic damage during long term storage. The mealy bugs multiply faster dur-

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ing the high temperature and humid conditions. Severely infested tubers are shrivelled, adversely affecting the quality and marketability. The mealy bugs can be removed physically by rubbing the tubers with soft brush or gunny bag pieces or coir pith dipped in a suitable contact insecticide solution. For long term storage, the tubers are required to be treated with the fungicide (i.e. Mancozeb @ 0.2%) along with insecticide (i.e. Monocrotophos @ 0.05%) before storage (Pillai and Palaniswami, 1984; Misra et al., 2007). The scale insects also cause minor weight loss to the tubers. Though their magnitude of damage is relatively less, the severe infection leads to shrinking of tubers. The scale insects can be controlled by the application of the cassava seed extract (3%) or chlorpyriphos (0.05%) on the infected tubers (Jayaprakas et al., 2008). Termites and wireworms also feed on the tubers causing partial to complete damage of tubers.

Nematodes The root knot nematode, Meloidogyne incognita and the root lesion nematode, Pratylenchus spp. are the two most important nematode pests causing economic damage to the EFY in India (Mohandas, 2008). The root knot nematodes that survive in the soil spread through infected tubers and enter the tubers through roots and produce typical galls on the roots. In corms and cormels, the infestations lead to irregular wart like projections, which become severe on advanced stages. Under severe infestations, the tuber tissues get dissolved and rot. In a pathogenecity experiment conducted at the CTCRI revealed that an initial inoculum density of 1000 infective second stage juveniles of the nematodes could cause significant reduction in the tuber yield (Mohandas, 2008). Under severe infection, it causes the premature multiple sprouting in the field. The root knot nematode continues to feed and multiply inside the corm and cormels even after harvest, during transportation, and in store causing reduction in weight and rotting. The weight loss is due to continuous feeding of tuber tissue by the nematode and also by the moisture evaporation from the wound caused by the nematode infestation. As the damaged tissues dry up, it gives a general dry rot appearance and a number of fungi invade the dead tuber tissue, subsequently. Pratylenchus spp., on the other hand, produce lesion on the root, cormels and corms initially and as the nematode multiply, the lesions spread on the entire surface. Cracking of tuber surface is also noticed. This nematode is found severe in var. Karunai Kizhangu, which is grown extensively in the Tamil Nadu State of India. Singh et al (2008) reported that another nematode species, Tylenchorynchus indicus causes severe damage in the EFY tubers under storage conditions in Bihar, India.

FOOD PRODUCTS FROM ELEPHANT FOOT YAM EFY as Food In India, the corms and cormels of EFY are usually boiled or baked and eaten as vegetable. The sprouts and petioles which resemble asparagus sprouts are used as vegetable in some parts of Asia (Misra et al., 2007). In Tripura, the tribal people consume the leaf lamina, petiole (pseudostem), corm and cormels of wild species of EFY (Sankaran et al., 2008a). In China, the bulbils of A. yuloensis are eaten by indigenous people in the Southern and South Western Yunnan Provinces (Long, 1998). EFY is one of the nutritious crops which contains (g/100 g fresh tuber): moisture (79.0), protein (1.2), fat (0.1), carbohydrates (18.4), minerals (0.8), calcium (0.05), phosphorus (0.34), iron (0.06), vitamin A (260 IU), thiamine (0.0006), niacin (0.07) and riboflavin (0.07) (Nedunchezhiyan et al., 2008). The corms are rich in calcium oxalate, an anti-nutritional factor that causes acridity.

Acridity in EFY The acridity associated with EFY is a major factor limiting its food value. The tubers of wild plants are highly acrid, and when ingested causes irritation and burning sensation in the mouth and in the throat. This effect is related to the presence of needle-like raphides of calcium oxalate. The intensity of irritation has been found to differ widely among different cultivars. Acrid cultivars show calcium oxalate levels in the range of 660-850 mg/100g, while non-acrid cultivars have acridity in the range of 120-140 mg/100g (Sundaresan, 2005). However, the cultivar “Gajendra”, which is a local selection from Kovvur area of Andhra Pradesh (India), is non-acrid and does not cause any irritation while eating. Acridity of the tubers can be reduced/ eliminated by suitable processing methods, i.e. boiling, baking, frying and drying by different modes. The traditional processing systems like pre soaking, addition of ingredients like tamarind, curd etc., in the cooking medium can reduce acridity. Among the various methods, boiling is found to be the most effective method in reducing the calcium oxalate content by 50% (Sundaresan and Nambisan, 2008). Studies on drum drying of EFY have indicated reduction of about 25% in calcium oxalate content in the dried product (Sundaresan and Nambisan, 2008). Indigenous people in Southern Yunnan and Hunan, Central China cook konjac tubers with plant ash or plaster in hot water to eliminate acridity. The Jinuo people of China use young konjac leaves (A. yunnanensis, A. yuloensis, A. krausei) as vegetables. They cook them in boiled water and fry in oil to eliminate bitterness and acridity

Post harvest handling, processing and value addition of elephant foot yam — An overview

(Long, 1998).

Traditional Indian Foods The EFY based traditional food products like deep fried chips and roasted cubes are common in Tamil Nadu State of India. The roasted yam cubes are prepared by cutting EFY into cubes and cooked with fresh spices (ginger and garlic) paste followed by slow cooking on a pan till the crispiness is obtained. Besides, it is common ingredient of Sambar, a savoury vegetable stew of drumsticks, okra (ladies finger), potatoes, eggplant, onion and tomatoes prepared with ground spices seasoned with tamarind juice, very common in South India. In Tamil Nadu and Kerala States of India, the traditional curry dishes like Kaalan, Mezukku Puratti, Poriyal, Aviyal are also prepared using EFYas an ingredient. In Goa, the EFY based soup Khatkhatem is prepared by cutting tubers in cube shape which are deep fried before it is added to a simmering pot of a vegetarian stew. Besides, the EFY chutney (mixed paste) is also prepared, which form important place in Goan dishes. In the Car Nicobar Islands of India, the tribals consume wild EFY tubers collected from the forest. They are boiled in hot water with salt and chilli powder and are consumed along with the wild pork dish (Damodaran et al., 2008) Traditional Japanese foods In Japan, the A. kojac is used in many traditional foods. Konnyaku, a traditional Japanese recipe, is a gel-like food having a light taste and an elastic texture. It is made by adding slaked lime into the colloidal solution of the flour obtained from the dried tubers of A. konjac (Nagayama et al., 1975). The Ito konnyaku is a type of Japanese food consisting of konjac cut into noodle-like strips. It is usually sold in plastic bags with accompanying water. The Konnyaku made in noodle form is called shirataki and used in other Japanese foods like sukiyaki and gyudon (Akesowan, 2002, 2008). Konjac can also be made into a popular Asian fruit jelly snack, known as ‘konjac candy’, served in plastic cups. The indigenous people of make noodles and sauce from elephant foot yam tubers. The konjac snack is very popular food item in the Western Hunan province of China (Long, 1998).

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are mixed with oil, tamarind paste, chilli powder, jiggery, asafoetida, ginger and garlic paste with garam masala and deep fried and stored in a bottle filled with vegetable oil.

EFY Cake Sundried rice is mixed with mashed elephant foot yam pulp and then cooked along with jiggery, salt, finely chopped ginger, cashew nuts, raisins, ground coconut, along with spices in oven to form delicious cake. EFY sweet meat (Ghulab Jamun) Cleaned EFY tubers are mashed and mixed with wheat starch, milk powder, baking powder and oil and made into small balls which are fried in hot oil till they become brown. The fried balls are soaked in sugar syrup for 30 minutes to one hour. EFY Poridge (Kheer) Boiled rice is mixed with mashed EFY pulp and cooled for 20 minutes to prepare the Kheer. Milk, cashew, raisins and sugar are added to make it delicious. EFY Cutlet Big pieces of the EFY are boiled and mashed and mixed with ginger paste, finely chopped onion, green chillies and salt fried for 10 minutes. Cooled balls are pressed flat and dipped into maida barter, rolled and fried in oil. EFY Pakoda The finely chopped EFY, garlic, onion, ginger, green chillies, curry leaves, cumin powder, coriander powder are mixed thoroughly with besan (powdered dal flour) barter to make them as small balls which are then fried in oil till they become golden brown. EFY Vada Boiled and mashed EFY tubers are mixed with rice powder. Small quantities of chopped onion, green chillies, ginger and coriander leaves, grated coconut, cumin and salt to make barter. The mix is made into flat structure and then is fried in oil.

Home made Foods Despite the processing constraints, several novel food products were developed in India from EFY tubers (Sabarmatee et al., 2007).

EFY Chutney Boiled and mashed EFY pulp are mixed with fenugreek seeds, saunf, mustard seeds, curry leaves, tamarind paste, garlic paste, ginger paste, finely chopped green chillies and coconut paste and cooked for 5-10 minutes to make chutney.

EFY Pickles Washed and peeled EFY tubers are cut into small cubes and

EFY Chop Boiled and mashed EFY pulp are mixed with ginger/garlic

Novel EFY Foods

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paste, chopped onion, turmeric powder, sambar powder, chilli powder and fried. The mixture is then made into small balls and dipped in the barter of gram flour and fried in hot oil till they turn brown.

EFY Mix Vegetable Chop Finely chopped carrot, sugar beet, beans, green peas, cauliflower, cabbage, onion, ginger, green chillies, along with salt are fried and mixed with boiled and mashed EFY. This mixture is made as small balls and then dipped into a barter of gram flour and fried till it turns golden brown. EFY Chips Washed and peeled elephant foot yam tubers are cut into very thin slices which are then sun dried for 3-4 days. The dried chips are then fried in oil and served by adding black salt, chat, spices and chilli powder.

(Huang and Lin, 2004). The KGM flour is prepared by washing, slicing, drying and milling the mature A. konjac tubers. After that the mixed power was separated to remove the konjac ‘dancing powder’, so the konjac flour can be obtained. It contains significant amounts of KGM ranging from 51.3 to 96.9% (Xiao et al., 1999). KGM with good water solubility was extracted and purified by a cheap and simple method including fat-extraction, protein-extraction, decolouring, centrifuge, precipitate and other procession from tubers of A. riveiri. The flow diagram for extraction of purified glucomannan is given in the Fig 2. The KGM consists of mannose and glucose in a molar ratio of 1.6:1 with  1–4 linkage (Chin et al., 2009). It has a strong water-binding ability and when combined with other polysaccharides (e.g., carrageenan and starch), it exhibits a synergistic effect on protein gelation and water-binding in

Industrial Food Products Processing is generally little more than an extension of home recipes. The EFY tubers are bulky and awkward to handle, and peeling and other preparation losses account as high as 10-30% which put several constraints in processing. Despite these constraints, many EFY based products are prepared and marketed in various countries. In Indonesia, the species A. onchophyllus is used to produce flour for industrial purposes (Nanda, 2008). The EFY is also used as animal feed in South East Asian countries. The corms of EFY are boiled and fed to pigs in Philippines and Brazil (Deo Shankar et al., 2008; Ngachan et al., 2008) while the big leaves are fed to pigs in China (Long 1998) Extruded Food products Extrusion technology at high temperature for short time period was tried at CTCRI, Thiruvanathapuram to develop a ready to eat snack product from EFY flour (Sheriff et al., 2008). Elephant foot yam tubers were washed, peeled and sliced. The sliced tubers were washed again and dried to a moisture content of 11%. The dried pieces were powdered using a hammer mill and the powder was sieved through 100mm mesh. The final moisture content of the powder was adjusted to 16%. This flour was sent through single screw laboratory extruder with a screw diameter of 19 mm at various temperature levels. These products had good expansion ratio, bulk density and acceptable texture qualities. The study showed that the EFY flour is suitable for the production of food quality snack products. Konjac Glucomannan (KGM) based Food Products The Konjac glucomannan is a neutral polysaccharide produced from the flour of Amorphophallus konjac tubers

Fig. 2: Method of extracting the purified glucomannan from A. konjac tubers (Xiao et al., ,1999)

Post harvest handling, processing and value addition of elephant foot yam — An overview

comminuted meat products. When konjac flour is dissolved in alkaline coagulant (such as calcium hydroxide, sodium or potassium carbonate), deacetylation occurs and a thermally stable gel is formed (Thomas, 1997). So it is used as a gelling agent in many meat products (Chin et al., 2000; Kao and Lin, 2006). It has high solubility and can be used in hot or cold liquids. The konjac flour is also used as a thickener in sauces, gravies, puddings and pie fillings without affecting the taste. These konjac based foods, are called as Moyu or Juruo in China, and Konnyaku or Shirataki noodles in Japan (Thomas, 1997). The KGM is also a source of soluble dietary fibre (Fang and Wu, 2004). It has wide applications in food (Cheng et al., 2002; Huang and Lin, 2004) and biomedical (Alvarez-Mancenido et al., 2006; Alonso-Sande, et al., 2006; Chen et al., 2005; Yu et al., 2006; Lu et al., 2008) domains.

Functional Foods Prepared from KGM Flour Konjac foods are a popular health food in the Asian markets (Konjacfoods.com, 2002-2004). It is also an important ingredient in many functional foods due to its physical and chemical properties. Fang and Wu (2004) explained various mechanisms of konjac in the functional foods. First of all, it can delay stomach emptying when taken as an edible A. konjac-based food. It may lead to a more gradual absorption of dietary sugar, which can reduce the elevation of blood sugar levels that is typical after a meal. The KGM is high in dietary fibre which is essential for human health. Like other soluble fibres, it can bind to bile acids in the gut and carry them out of the body in the faeces, which requires the body to convert more cholesterol into bile acids (Wu and Peng, 1997). It may help weight loss by filling the stomach and making a person feel full. Walsh et al., (1984) reported weight loss averaging 2.5 kg in adults when one gram of glucomannan was taken with a cup of water one hour before each meal for 8 weeks based on a double-blind study. The KGM can lower the quantities of serum cholesterol and low-density lipoprotein cholesterol (Arvill and Bodin, 1995), triacylglyceride (Takigami, 2000) and also involved in the regulation of low blood sugar levels in Type 2 diabetes (Chen et al., 2003), body weight control and regulating immune functions of the human body. In China, the konjac blends are used to improve the texture of many low fat functional meat emulsion products (Chin et al., 1998). Osburn and Keeton (1994) found low-fat (~ 10%) prerigor fresh pork sausages containing 10 or 20% konjac gel had a higher shear value than the high-fat control (40%) but lower than the low-fat control (10%). Huang et al., (1998) found that the low-fat Chinese-style sausages containing 10% or 20% konjac gels to be of acceptable quality. Park (1996) reported that adding konjac flour enhanced the shear stress of surimi gel and produced heat-tolerant and stable freeze–thaw fish

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gels. Chin et al., (1998) also reported that low-fat (