Maltose preparation

Maltose, prepared from starch by treatment with barley malt extract and repeatedly recrystallized from 90 % alcohol, showed the same... 

During illness, carbohydrates can be provided as small frequent meals, as drip-feeding, and sometimes as continuous drip-feeding. Using alpha-dextrin maltose preparations has the added advantage of low osmolality and easy digestion. 

A mixture of dextrins and maltose prepared from cornstarch by acid treatment or by digestion with enzymes. It is used mainly in milk formulas for infants. 

Amylase occurs in many plants, such as barley, wheat, rye, soy beans, and potatoes, where it is generally accompanied by some a-amylase. [ -Amylase initiates hydrolysis at the nonreducing end of an amylose or amylopectin chain, and removes maltose units successively until the reducing end of the molecule is encountered in amylose or a branch is met in amylopectin. ( -Amylase is used commercially in the preparation of maltose symps. After P-amylase hydrolysis of amylopectin there remains a P-amylase limit dextrin. ( -Amylase has been used as a probe of the fine stmcture of amylopectin (43-46). 

Such symps are used in the preparation of confections, preserves, and other foodstuffs. The maltose in malt symps is important in brewing (see Beer). Intravenous feeding (primarily in Europe and Japan) and sports beverage formulations take advantage of the fact that energy release from maltose becomes accessible to the body at a slower rate than energy suppHed by monosaccharides (31). 

The living character of the ROMP promoted by the initiator Ru(CHPh)(Cl)2 (PCy3)2 (Cy = cyclohexane) was tested with the synthesis of diblock, triblock, and tetrablock copolymers of norbornene derivatives carrying acetyl-protected glucose, [2,3,4,6-tetra-O-acetyl-glucos-l-O-yl 5-norbornene-2-carboxylate], A or maltose groups, [2,3,6,2/,3/,4/,6/-hepta-0-acetyl-maltos-1-O-yl 5-norbornene-2-carboxylate], B, shown in Scheme 41 [102]. The AB, ABA, and ABAB structures were prepared by sequential addition of monomers with narrow molecular weight distributions to quantitative conversions. 

In addition to possible variations between methods, there may also be variations in Tg within a method, depending on the measurement protocol employed. For example, the DCS Tg midpoint for a quench-cooled ( 100 K/min) maltose sample, heated at a scanning rate of lOK/min, was 43.1 0.21 °C, whereas for a maltose sample prepared using equal heating and cooling rates of lOK/min the Tg was 41.2 0.10°C (Schmidt and Lammert, 1996). For the same samples, DSC Tg Active temperatures were also calculated. Tg Active for the quench-cooled sample was 41.0 0.20 °C, whereas for the equal-rate sample, Tg Active was 38.6 0.06 °C. 

Momenteau et al. described the preparation of amphiphilic glyco-conjugated meso-monoarylbenzochlorins from meso-monoarylporphyrins.74 The reaction of metal free benzochlorin 94 with 1-bromoethoxy-per-acetyl-maltose, in DMF and in the presence of potassium carbonate, gives compound 95b in 95% yield (Scheme 12). After deacetylation of 95b maltosylchlorin 95a was obtained quantitatively. 

This particular trimethylglucose is unique in that it was separated in crystalline form from the hydrolyzates of the methyl ethers of several naturally-occurring glucose polymers almost two decades before it was synthesized from glucose. These natural sources, which still furnish the most convenient routes for the preparation of 2,3,6-trimethyl-D-glucose, include maltose,124-128 cellobiose,127,128 lactose,122-181 starch,71,182 glycogen,188,184 cellulose,185-187 and lichenin. 188,189 The literature pub-... 

It is important to note that no evidence of maltase activity was found in the amylase preparations even when the highest concentrations used in these comparisons were allowed to react for twenty-four hours with one per cent maltose under the conditions for the hydrolysis of starch. Similarly, no evidence was obtained for the presence of any other contaminating or extraneous carbohydrases in the amylase preparations. Partial inactivation of the amylase under a number of different conditions failed to give any evidence of selective inactivation such as might be expected if more than one enzyme were present. The substrates used for measuring the activity of the partially inactivated amylase were starch and starch hydrolyzates that had already been extensively (58) J. Blom, Agnete Bak and B. Braae, Z. physiol. Chem., 250, 104 (1937). 

Prior to 1939, however, it was not known whether the cyclodextrins were products of the synthetic metabolism of Bacillus macerans, and therefore, perhaps, quite different from the components of starch, or whether they were formed by a single enzyme and therefore closely related to the starch structure. Then, Tilden and Hudson announced the discovery of a cell-free enzyme preparation from cultures of Bacillus macerans which had the ability to convert starch into the Schardinger dextrins without the production of maltose, glucose, or any other reducing sugars. They thus concluded that the Schardinger dextrins were either the true components of starch or closely related to such true components. 

Hydroxypyridonimine analogues (177) of the much-studied 3-hydroxy-4-pyridinones (cf. Section 5.4.5.5.2), are prepared from maltose or lactose. They form stable iron(III) complexes. 

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