Tuber value

Cassava is one of an important economic plants of Thailand. Thailand exported cassava products eg. cassava chip, peUet, flour and starch, etc. which are low value. The amount of the products was approx. 20 milhon metrictons a year in 1993. However, by the process, some carbohydrates in cassava tuber still waste and further cause pollution. 

Nufrifional bars confaining cold-extruded whey have been developed (Joseph et ah, 1995). Extrusion was conducted at 37 °C to produce a low-calorie product with high nutrient value. A weaning food was obfained by extending WPC, WPI, or a-LA with taro flour, which is derived from a tropical root tuber (Onwulata et ah, 2002). The extrudates were pulverized, made into powders, and rehydrated into pastes. WPI coblended extrudates produced the best consistency. 

Field test work with technically pure gamma isomer of hexachlorocyclohexane has been extensive and involved and is being continued. It was necessary to know such factors as insecticidal value in field applications as compared to other insecticides, as well as residual life, residue from the poison standpoint, and residual taste or odor factors. These factors have been worked out on numerous crops and some of the results are dealt wTith in this paper. Because the pure gamma isomer was found to be effective on insects in the soil as well as on insect infestations on plants, its residual life in soil of all types and effects on tuber and root crops were also of major importance. 

Of the 190 accessions evaluated after one year s growth in Florida, 38 showed tuber formation. Tender leaves are incorporated in the food preparations in the South Asian region. Leaf protein concentrate (crude protein 51.9%) prepared from leaves yielded a PER value of 2.2 in comparison to 2.7 for corn-soy control. International Winged Bean Trials conducted in 19 countries recommend 5 varieties as having the best yield potential under varying environmental conditions. 

Tubers Tubers are quite commonly consumed by villagers in Burma. Other tropical countries also report sporadic use of winged bean tubers (59). However, in comparison to the available data on the nutrient, anti-nutrient composition and the protein quality of the seed flour, published data on the nutritional value of winged bean tuber is somewhat limited. The few reported studies dealing with a larger number of varieties grown in different locations (25,67-71) show that tubers are mainly composed of protein and carbohydrates. 

Normal-phase TLC has been employed for the separation of two new flavans in the extract of the undergorund tubers of Cyperus conglomeratus Rottb. (family Cyperaceae). The underground tubes were dried, ground and were extracted with with petroleum ether diethyl ether-methanol (1 1 1, v/v) for 24 h at ambient temperature. The extract was defatted with cold methanol. The components of the extract were preliminarily separated by traditional column chromatography followed by GC/MS and TLC. New flavans (5-hydroxy-7,3, 5 -trimethoxyflavan and 5,7-hydroxy-3, 5 -dimethoxyflavan) were separated on silica TLC layers using petroleum ether-diethyl ether (1 3, v/v) with the RF values of 0.50 and 0.37 for dimethoxy and trimethoxy derivatives, respectively [115]. 

The members of this family—botanically named the Solanaceae, after the nightshade plant—are all valued for their fruits, with the exception of the potato, where it is the tubers that are eaten. Potatoes do bear small, green tomato-like fruits, but these are poisonous, and should never be eaten. The family includes ... 

The bulk of potato tubers is made up of parenchyma cells that have thin, non-lignified, primary cell walls (Reeve et al., 1971 Bush et al, 1999, 2001 Parker et al., 2001). Unless stated to the contrary, potato cell walls refers to parenchyma cell walls. These walls and their component polysaccharides are important for a number of reasons they form part of the total intake of dietary fiber, influence the texture of cooked potato tubers and form much of the waste pulp that is produced in large amounts by the potato starch industry when starch is isolated. The pulp is usually used as cattle feed, but potentially could be processed in a variety of ways to increase its value (Mayer, 1998). For example, the whole cell-wall residues could be used as afood ingredient to alter food texture and to increase its dietary-fiber content, or cell-wall polysaccharides could be extracted and used in a similar way or for various industrial applications (Turquois et al., 1999 Dufresne et al, 2000 Harris and Smith, 2006 Kaack et al., 2006). 

The effects of storage on lipids depend on potato variety (Mondy et al., 1963). Tuber storage at 4°C resulted in an initial small increase in total fatty acid content (Dobson et al., 2004). Prolonged storage resulted in a fall to the initial values detected close to harvest. The content... 

PME activity increased by about 65% in the fresh tubers after 20 min at 60° C, but after 60 min it declined to about 40% of its original value. At 60°C, PME in potato tissue (ev. Kennebec) appears to have a relatively short inactivation time, or possibly its optimum activation temperature is <60°C. In this experiment also, PME aetivity deelined to less than 10% of its original value after 5 min at 70° C, and no aetivity at all was detected when the time at this temperature was prolonged. Similarly, no PME activity was detected in samples blanehed at 80°C. In potato tubers (cvs. Nicola and Irene), Van Dijk et al. (2002) found that the PME activity tended to remain eonstant during preheating at 60°C for 60 min. 

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