Tuber

Tubers differ from the root crops in containing either starch or fructan instead of sucrose or glucose as the main storage carbohydrate. They have higher dry matter and lower fibre contents (see Table 21.1) and consequently are more suitable than roots for feeding pigs and poultry. 

In potatoes Solarium tuberosum) the main component is starch. The starch content of the dry matter is about 700 g/kg this carbohydrate is present in the form of granules that vary in size depending upon the variety. The sugar content in the dry matter of mature, freshly lifted potatoes rarely exceeds 50 g/kg, although values in excess of this figure in stored potatoes have been obtained. The amoimt present is affected by the temperature of storage, and values as high as 300 g/kg have been reported for potatoes stored at 21 °C. 

The crude fibre content of potatoes is very low, usually less than 40 g/kg DM, which makes them particularly suitable for pigs and poultry. However, the protein in uncooked potatoes is frequently poorly digested by these animals, and protein digestibility coefficients as low as 0.23 have been reported for pigs. In similar trials with cooked potatoes, digestibility coefficients for protein generally exceed 0.70. 

Potatoes contain a protease inhibitor that reduces the digestibility not only of potato protein but also of protein in other components of the diet. The inhibitor is destroyed by heating it is normal practice to cook potatoes for pigs and poultry, although cooking is unnecessary for ruminants, presumably because the inhibitor is destroyed in the rumen. For pigs and poultry the ME value of cooked potatoes is similar to that of maize, about 14-15 MJ/kg DM. 

Potatoes are a poor source of minerals, except for the abundant element potassium the calcium content is particularly low. The phosphorus content is rather higher, since this element is an integral part of the potato starch molecule, but some 20 per cent of it is in the form of phytates (see p. 115). 

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Konjac flour, derived from the konjac plant tuber, has a long history of use in the Ear East, but is a newcomer to the United States. It reacts with many starches to enhance the viscosity of both, and is used in gels that are stable in boiling water. 

The compound is not effective when appHed as a preharvest dormancy agent on potatoes and it should not be used until injuries to the tuber coat have healed. Neither should it be appHed until some suberization has occurred, generally two weeks after storage at >10° C (23). CIPC is widely used outside the United States on a number of crops as a herbicide. 

Only traces of mannose occur in the hydrolysates of some monocotyledon stems (7,9) although glucomannans occur in the tubers and leaves of some monocotyledon species (72). 

The major use of alkan olamines in agricultural products is as a neutralizer for acidic herbicides. They also contribute increased water solubiUty, reduced volatility, and more uniform solutions. Various ethan olamines are reported in formulations to improve potato tuber size (219) and enhance the resistance to salt of some crops (220). 

Ethylene oxide Lab method using charcoal absorbent tubers, solvent desorption and gas chromatography 26... 

Dioscorine has also been found in D. hispida tubers by Zeyva and Gutierrez. ... 

C. decumbens Pers. According to Asahina and Motigase the tubers... 

FIGURE 16.23 Inulln isolated from small (—). medium ( ) and large (A) tubers separated on P-6 (140 X 1.5 cm) flow rate 0.33 ml/min eluenf. H20(dest) + 0.002% NaNa mass detection Waters 403 R differential refractive index detector, sensitivity 8X applied sample solution volume I ml of a 20-mg/ml aqueous inulin solution. 

Erd-mandel, /. chufa (Cyperua eaculentua), chufa tuber, -mehl, n. Kieselgur, -mess-kunst, /. geodesy. 

Potatoes will start to sprout after a long period in storage. This can be checked by spraying the freshly lifted tubers with a chemical sprout depressant. 

Pipecolic acid has been isolated and identified by various researchers from several legumes, hops, mushrooms, potato tuber, green pepper, tulip, celery, asparagus, Rhodesian teak, barley, and coconut milk. Grobbelaar et al. 58) isolated large quantities of free (-)pipe-colic acid from Phaseolus vulgaris. 

Neurotransmitter and biogenic amine derived from the amino acid histidine synthesized in hypothalamic tuber-omamillary neurons (TMN) to maintain wakefulness, feeding rhythms, energy balance, neuroendocrine autonomic control, and memory functions prominent immu-nomodulator and proinflammatory signal released from mast cells in response to allergic reactions or tissue damage. 

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