Reducing sugar concentration

Enzyme activity towards carboxylmethyl cellulose (CMC) was measured by combining 50 fiL enzyme with 0.5 mL of 0.5% CMC in pH 4.8 sodium citrate buffer and incubating at 50°C for 10 min. After this, the reaction was stopped by addition of 1.5 mL dinitrosalicylic acid reagent and the resultant color, which was measured at A54onm, related to the reducing sugar concentration. 

Determine the total reducing sugar content in the sample by using the DNS method and prepare a curve to show the change of the reducing sugar concentration with time. 

It is clear, however, that the operation of the SSF process in continuous reactors led to a worse performance than the one obtained in the batch experiments, with the same enzyme and yeast concentrations in the reactor and similar total reducing sugar concentration (initial, in the batch run and in the feed, for the continuous run). The concentration of free glucose in the effluent was lower than 1 g/1 for all the tested flow rates, except for the two... 

Total reducing sugar concentration (TRS) and glucose concentration (G), in the outlet of reactors 1, 2, and 3, for different feed flow rates (ftccd)-T Assay time... 

The winemaker s challenge is to optimize those conditions that favor growth of fermentative yeasts (Saccharomyces) resulting in complete alcoholic fermentation (final reducing sugar concentrations of <0.2% w/v) while avoiding formation of undesirable odors or flavors. Ideally, completion of alcoholic and malolactic fermentations should result in a wine that is nutritionally insufficient to support further microbiological activity (i.e., the wine has become a nutrient desert ). 

Colorimetric Methods. Numerous colorimetric methods exist for the quantitative determination of carbohydrates as a group (8). Among the most popular of these is the phenol—sulfuric acid method of Dubois (9), which rehes on the color formed when a carbohydrate reacts with phenol in the presence of hot sulfuric acid. The test is sensitive for virtually all classes of carbohydrates. Colorimetric methods are usually employed when a very small concentration of carbohydrate is present, and are often used in clinical situations. The Somogyi method, of which there are many variations, rehes on the reduction of cupric sulfate to cuprous oxide and is appHcable to reducing sugars. 

The dilute acid of HCl was used as a pretreatment agent. In the first method, bean curd refuse was pretreated without heating. An amoimt of 0.5 g bean curd refuse was dipped in 10 ml of 1 mol/1 HCl aqueous solution for 1, 3, 6 and 24 hours. In the next, 0.5 g bean curd refuse was dipped in 10 ml distilled water or HCl solution in the concentration range of 0.01-1 mol/1 and held in a steam-heated auto clave at 121 C for 1, 15 or 30 min. After neutralization with 5 mol/1 NaOH solution, the concentrations of reducing sugar, total sugar and TOC were measured for the pretreated solution. 

If a semipermeable membrane separates two identical solutions, solvent molecules move in both directions at the same rate, and there is no net osmosis. The two sides of the membrane are at dynamic equilibrium. The situation changes when the solutions on the two sides of the membrane are different. Consider the membrane in Figure 12-14a. which has pure water on one side and a solution of sugar in water on the other. The sugar molecules reduce the concentration of solvent molecules in the solution. Consequently, fewer solvent molecules pass through the membrane from the solution side than from the pure solvent side. Water flows from the side containing pure solvent to the side containing solution, so there is a net rate of osmosis. 

Citric acid concentration (%) pH Reducing sugars (%) Non-reducing sugars (%)... 

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