Of reducing sugars

Benedicts reagent (Section 25 19) A solution containing the citrate complex of CUSO4 It is used to test for the presence of reducing sugars... 

Emmerich Method. This method is for determination of trace amounts of reducing sugars in pure sucrose and white and refined sugars with reducing sugar content up to 0.15%. The test is carried out in a nitrogen atmosphere and is based on the reduction of 3,6-dinitrophthahc acid. 

Composition. Molasses composition depends on several factors, eg, locality, variety, sod, climate, and processing. Cane molasses is generally at pH 5.5—6.5 and contains 30—40 wt % sucrose and 15—20 wt % reducing sugars. Beet molasses is ca 7.5—8.6 pH, and contains ca 50—60 wt % sucrose, a trace of reducing sugars, and 0.5—2.0 wt % raffinose. Cane molasses contains less ash, less nitrogenous material, but considerably more vitamins than beet molasses. Composition of selected molasses products is Hsted in Table 7. Procedures for molasses analysis are avadable (59). 

Oxidation of the aldehyde group of an aldose to form a carboxyUc acid or carboxyUc acid anion is often used analytically to determine the amount of reducing sugar. The Benedict and Fehling methods measure the amount of reducing sugar present in a fluid. In these reactions, the oxidant, Cu ", is reduced to Cu". Cu" precipitates as CU2O, which can be measured in a variety of ways. In the ToUens test, Ag" is reduced to Ag. ... 

Fig. 9.—Reaction model for alkaline degradation of reducing sugars.

There is little doubt that Shallenberger s AH,B hypothesis is the most plausible concept in the explanation of the initial stimulation of the sweet-taste receptor. However, it was unfortunate that the evidence was accrued largely with the aid of reducing sugars, which, in solution, equilibrate between many isomers, so that it is not possible to relate total gustatory response to any one particular stereochemical structure It is also not... 

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. 

Mode of action and kinetics. Routine polygalacturonase assays were performed in a reaction mixture containing 50 mM Na-acetate pH 4.2 and 0.25 % w/v pga at 30 °C. The release of reducing sugars was determined according to Stephens et al. [9]. For determination of pH optima the 50 mM Na-acetate buffer was replaced by Mcllvain buffers. 

PG activity was assayed from cells grown in a medium containing 1% glucose in one-litre self-induced anaerobic fermentation for 5 days by increase of reducing sugars. Enzyme activity increased from pH 3.0 to pH 5.0 (citrate buffer) and decreased drastically above 5.0 (phosphate buffer), but activity was not affected differentially by the two buffers used (data not shown). PG activity increased almost linearly from 20°C to 40°C but above this optimum, activity was lost rapidly and the enzyme was completely inactivated at 60°C and 70°C after 10 and 6 min, respectively (data not shown). No PL, PGL or PME were detected. 

Gritzapis, P. and Timotheou-Potamia, M. (1989). Determination of reducing sugars with a 2,4-dinitrophenolate-selective membrane electrode. Anal. Chim. Acta 218, 37-46. 

Peris-Tortajada, M., Puchades, R., and Maquieira, A. (1992). Determination of reducing sugars by the neocuproine method using flow injection analysis. Food Chem. 43,65-69. 

A number of reducing agents have been determined directly using tetrazolium salts. Thus, the analyses of reducing sugars,423,424 hydraz-ides, 425 sulfides and thiols,426 ascorbic acid,427,428 formaldehyde,429 L-... 

The Maillard reaction is likely to take on additional significance with the introduction of many new protein and peptide pharmaceuticals. For example, Tarelli et al. have demonstrated that lysine vasopressin undergoes rapid glycation in the presence of reducing sugars in both aqueous and solid formulations and that the N-terminal adduct can form rapidly even at — 20°C [52], A textbook that deals with the consequences for the chemical and life sciences of the Maillard reaction has been published [53]. 

In all cases where the chemical properties of these preparations have been studied the active material appears to be predominantly carbohydrate in nature, containing in the case of the A factor 50-70% of reducing sugar, 5.7% nitrogen and giving by colorimetric estimations 25-30% of glucosamine on hydrolysis. 

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