Carbohydrates water content effect

In plants, the meristematic tissues in general are particularly rich in potassium, as are other metabolically active regions, such as buds, young leaves, and ioot tips. Potassium deficiency may produce both gross and microscopic changes in the structure of plants. Effects of deficiency reported include leaf damage, high or low water content of leaves, decreased photosynthesis, disturbed carbohydrate metabolism, low protein content and other abnormalities. 

Because water plasticizes hydrophilic food components, their glass transition is strongly dependent on water content. The effect of water on the glass-transition temperature of several amorphous carbohydrates, calculated with the Gordon Taylor equation [B.79], is depicted in Fig. 6.4-6. Within the range of the materials shown, Tg decreases with lower average molecular weight and/or increased concentration of plasticizer (water). 

Water acts as a plasticizer and increases the mobility of the hygroscopic hemicellulose macromolecules, and this leads to a lower glass transition temperature under moist conditions. Measurements (4) as well as calculations (6) show a decrease to approximately 50 C at 20% water content. In other carbohydrates water also shows a strong softening effect (12,13). 

Maaruf AG, Man YBC, Asbi BA, Junainah AH, Kennedy JF, (2001) Effect of water content on the gelatinisation temperature of sago starch . Carbohydrate Polymers, v46 n4 331-337. 

Ghazaly, K.S. 1992. Sublethal effects of nickel on carbohydrate metabolism, blood and mineral contents of Tilapia nilotica. Water Air Soil Pollut. 64 525-532. 

Demulcents, e.g., pectin (home remedy grated apples) are carbohydrates that expand on absorbing water. They improve the consistency of bowel contents beyond that they are devoid of any favorable effect... 

Saline laxatives like MgS04, Mg(OH)2, Mg2 Citrate and Na+ Phosphates act via their osmotic pressure to retain water in the colon. Other osmotic laxatives are carbohydrates such as lactulose, glycerin, sorbitol, and mannitol. They are not absorbed and are resistant to digestion in the small intestine. Most agents are orally administered. It should be noted however that glycerin, sodium phosphates and sorbitol are formulated for rectal use. From lactulose lactic and acetic acids are formed by intestinal bacteria and apart from its osmotic effects it thus acidifies the content of the colon. The reduction of the pH stimulates motility and secretion. 

Many of the same conclusions may be drawn from results with synthetic auxins as from indole-3-acetic acid water intake increased, there was a lessening of the downward translocation of photosynthate with temporary increases of soluble carbohydrates in the leaves, and alterations appeared in the metabolic ratq and direction and in enzyme activity. However, the direct site of action is not known, and many of the effects are puzzling. n-Fructose oligosaccharides in artichoke and chicory storage-tissue were diminished by 70% (calculated on the content of dry matter) in 6 days... 

---