Table 13.2 Summary of nutritional aspects of konjac Glucomannan (KGM)
KGM as food products /associates | Nutritional properties | References
Food additives | Preserving quality in frozen rice starch-based food products; possessed a better color with a slight fishy smell | Charoenrein et al. (2011); Xu et al. (2014)
Cryoprotectant agents | Effective and healthy cryoprotectant in the surimi products made from different fishes | Xiong et al. (2009)
Potential fat analogue/ fat replacers | Reducing the fat content in frankfurters prepared with konjac gel as a fat substitute; Freezing/thawing process strongly affected and enhanced | Lin and Huang (2003); Jimenez-Colmenero et al. (2010); Shen et al. (2011); Li et al. (2014)
Gel reinforcement | Restructured seafood products are processed from minced and/or chopped muscle, usually with added ingredients such as KGM to make products with a new appearance and texture | Dave et al. (1998); Iglesias-Otero et al. (2010); Chanarat and Benjakul (2012)
Prebiotic properties | Glucomannans hydrolyzates (GMH) can act as a prebiotic by stimulating selectively the growth of gut-friendly bacteria and serving as valuable functional foods | Elamir et al. (2008); Al-Ghazzewi amd Tester (2012); Bateni et al. (2013); Al-Ghazzewi and Tester (2014)
Traditional food products | Konjac based foods, are called as Moyu or Juruo in China, and Konnyaku or Shirataki noodles in Japan | Thomas (1997); Fang and Wu, (2004); Chua et al. (2012)
13.6.3 KGM in Bio-film Production
The konjac glucomanan flour, after absorbing water, can swell by 800-1,000 times with a good viscosity. Therefore, it has industrial uses in textiles, paper matting, petrol and chemical processes. Among natural polymers, KGM is a good additive for packaging materials. It has attracted great interest since it has excellent film-forming ability, good biocompatibility and biodegradability. Several articles reported that the blended films of KGM and other natural or synthetic polymers, such as pullulan (Yue et al., 1995), cellulose (Yang et al., 1998; Zhang et al., 1997), polyvinyl alcohol (Li and Xie, 2004) and methylcellulose (Li et al., 2006), are being used in the food and pharmaceutical industries. Lu et al. (2008) prepared a novel anti-bacterial film by blending KGM and poly-diallydimethylammonium chloride in an aqueous system. The films exhibited an excellent antibacterial activity against Bacillus subtilis and Streptomyces aureus. When KGM is blended with chitosan and nisin, it inhibits the growth of pathogenic bacteria like Staphylococcus aureus, Listeria monocytogenes and Bacillus cereus (Li et al., 2006).
13.6.4 Other Uses of KGM
Glucomannan has been used in Asia for centuries as traditional foods, such as noodles, tofu and heat stable gelled food products. Zhou et al. (2013) investigated the effects of KGM on Chinese noodles made from low-protein wheat flour. The noodles were prepared from wheat flour/KGM blends by replacing low-protein flour at 1, 2, 3, 4 and 5 % with KGM. The cooking and textural properties, microstructure and sensory characteristics were evaluated. KGM addition contributed to a higher cooking yield and lower cooking loss for the resultant noodles. The sensory quality of KGM noodles was better than that of the control, indicating the potential for improving textural defect of noodles prepared from low-protein wheat flour by using KGM. To briefly summarize:
• KGM is a natural vegetable gum, affirmed as GRAS (generally recognized as safe) for use as a food ingredient since 1997.
• It is generally used in the food industry as a gelling agent, thickener, film former, emulsifier, stabilizer and soluble fibre.
• KGM has applications as a food additive, including bakery products, beverages, breads and batters, candies and confections, condiments, dairy products, processed
foods, salad dressings, soups and gravies, snack foods, frozen and refrigerated dishes, and many other products (Chua et al., 2010).
• KGM is regarded as a non-caloric food ingredient, due to one of its primary benefits as an indigestible dietary fibre, which has been demonstrated to be effective in weight reduction, modification of intestinal microbial metabolism and cholesterol reduction (Chua et al., 2010; Zhou et al., 2013).
• KGM is an effective filler for improving both strength and adhesiveness of myofibrillar protein gels (Xiong et al., 2009).
• In Europe, KGM has been given an E425 agreement number by the European Food Safety Authority (EFSA) (FSA, 2007). Since 1994, KGM has been approved as a food additive by the US Food and Drug Administration (FDA) (Takigami, 2000; Zhang etal, 2005). In 1996 it was also passed as a binder in meat and poultry products by the US Department of Agriculture (USDA).
13.7 Processing as Pharmaceutical Supplements
The EFY tuber is also widely used in many Ayurvedic preparations. In recent years the popularity of complementary medicine has increased. Over 50 % of all modern drugs are from natural product origin and they play an important role in drug development programmes in the pharmaceutical industry. Epidemiological evidence suggests that dietary factors play an important role in human health and in the treatment of certain chronic diseases including cancer. The tubers of wild plants are highly acrid and cause irritation in the throat and mouth due to excessive amounts of calcium oxalate present in the tubers. The tubers are traditionally used as anodyne, anti-inflammatory, anti-haemorrhoidal, haemostatic, expectorant, carminative, digestive, appetizer, stomachic, anthelmintic, liver tonic, aphrodisiac, emmenagogue and rejuvenating tonic. They are also used in arthralgia, elephantiasis, tumours, inflammations, hemorrhoids, hemorrhages, vomiting, cough, bronchitis, asthma, anorexia, dyspepsia, flatulence, colic, constipation, helminthiasis hepatopathy, splenopathy, amenorrhea, dysmenorrhoea, seminal weakness, fatigue, anemia and general debility. The tuber is reported to have antiprotease activity, central nervous system (CNS) depressant activity, analgesic activity and cytotoxic activity (De et al., 2010).
EFY has many medicinal properties. In India, it is used in Ayurvedic drugs in the treatment of inflammatory conditions, hemorrhoids, rheumatism and gastrointestinal disorders (Raghu et al., 1999). This herb is also used in earache, pain, intercostal neuralgia, puerperal fever and swelling of the throat (Joshi, 2000). The paste of tubers is applied externally to reduce pain in arthritis. In China, A. konjac has been used in Traditional Chinese Medicines as an immune-regulation and health food for a long time (Vuksan et al., 2001).
KGM, a delicacy in foods and rich in nutrients, is popular as a vegetable in various delicious cuisines. They possess blood purifier properties and have been used traditionally for the treatment of piles, abdominal disorders, tumours, enlargement of spleen, asthma and rheumatism. They are traditionally used in arthralgia, elephantiasis, tumours, inflammations, hemorrhoids, hemorrhages, vomiting, cough, bronchitis, asthma, anorexia, dyspepsia, flatulence, colic, constipation, helminthiasis, hepatopa-thy, spleenopathy, amenorrhea, dysmenorrhoea, seminal weakness, fatigue, anemia and general debility. The tuberous roots of the plant have also been reported to possess tonic, stomachic and appetizer properties (Singh and Wadhwa, 2014).