Glucose/fructose ratio

The initial HMF content in all honey samples was lower than the allowed maximum limit of 40 mg/kg as recommended by Turkish Alimentarus Codex [17], for honey in general. These results contradict the observation made by some authors that the types of honey produced in subtropical climates have high HMF exceeding 40 mg/kg [18]. However, the European Union council directive also allows for a maximum of 80 mg/kg for honey from tropical climates. The HMF level in honey is said to depend on the type of sugar present in honey and the fructose glucose ratio [19]. The HMF formation results from the acid catalyzed dehydration of hexose... 

Crude muscle hexokinase phosphorylates both glucose and fructose. The two activities may be separated with ammonium sulfate. Crude extracts have a fructose glucose ratio of 0.26 on fractionation with ammonium sulfate between 0.35 and 0.54 saturation, a fructose glucose ratio of 0.148 is observed. Muscle fructokinase is not inhibited by glucose and is saturated by its substrate at unusually high concentrations. The reaction product is not the expected fructose-6-phosphate but rather fructose-1-phosphate. Muscle glucokinase has not as yet been examined to any extent for its specificity. 

Bacterial f. of the high-molecular levan type are extracellular products of Bacillus polymyxa when grown on 4-16% sucrose solutions or on -+sucrose molasses. The m.w. is 2 x 10 , the fructose glucose ratio is 12000 1, and 72% of the fhictose has a P-1,2 backbone with 12% branch points of P-1,2-linkages and 13% terminal groups. The water solubility of f. decreases with increasing m.w. 

Rats 61 2 vs 52 2% Dogs 29 2 vs 15 1% Ca from CCM in AJ better retained than diat from OJ In rats Ca retention CCM-AJ and CCM-OJ > milk (42 2%) Hi er ratio of fructose glucose and lower acid content of CCM-AJ improved Ca retention in rats... 

Other systems for fractionating D-fructose-D-glucose mixtures are based on cationic resins in the hydrogensulfite-sulfite form,55 strontium sulfonate resin,58 silver sulfonate resins,57 and polymeric aryl-boronic resins.58 The arylboronic systems have been used to effect isomerizations to relatively high D-fructose D-glucose ratios, as well as to cause fractionation. 

The ratio [NADH]/[NAD] controls the formation of D-fructose. The ratio is low in cytosol, leading to a concentration of seminal D-fructose derived from blood D-glucose without energy expenditure beyond that required to maintain a favorable ratio of the nicotinamide nucleotides.92... 

The average reducing sugar/soluble solids content was 63.5% The average ratio of fructose/glucose was 1.17. Both values compare with those of standard commercial tomato cultivars (8). 

For different feed compositions, a maximum value of PR was found for a feed ratio of 40/60. This demonstrates the existence of an optimum. The results obtained in this study were compared with the simulation of an SMB bioreactor for the inversion of sucrose to fructose and glucose and found to be consistent [160]. 

A good example of using adsorptive separation in a non-refining/petrochemical application is the separation of fructose from an aqueous solution of mixed sugars. This process allows the production of high concentration fructose which has a much higher sweetness to calorie ratio than simple glucose or sucrose. As in fine chemical and pharmaceutical applications we can often use adsorption when distillation is not possible or feasible or when the material is thermally sensitive. 

The main compounds in honey are glucose and fructose, and their ratio can be used as a check for authenticity regarding their botanical origin [49], as shown for some honeys in Table 19.2. 

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