食品分析实验报告 DNS.docx

Date:2011-05-22Experimental title:Determination of reducing sugar content—DNS methodPrinciple:Determination of reducing sugar is the basic method for the determination of sugar content.Reducing sugar is free aldehyde or ketone containing sugar. Monosaccharides are reducing sugars, disaccharides and polysaccharides are not necessarily reducing sugar.Lactose and maltose are reducing sugars, sucrose and starch non-reducing sugar.The solubility of the different use of sugar, you can sample monosaccharide, disaccharides, and polysaccharides were extracted.(Not reducing) disaccharides and polysaccharides can be double-acid hydrolysis method. Outing to double sugar and reducing the degradation into a single sugar determination. In the sample were calculated reducing sugars content.Content of reducing sugar with glucose instead.Procedures:Reagent preparation:DNS Reagent configurationIn NaOH solution, by adding dinitrosalicylic acid solution and potassium sodium titrateNaOH solution by adding crystalline phenol, add water to dissolve, and finally set the volume.Take (2) 69mL anhydrous sodium sulfite 6.9 g, to dissolveTo (3) into (1), the completely dissolved, stored in brown reagent bottle. At room temperature, place 7-10 days later to useGlucose standard solution configurationAccurately weigh 100 mg of analytical grade glucose (pre-dried at 105 ℃ to constant weight), dissolved in distilled water with a small amount of volume to 100mL, refrigerator use.Operation methodsTake six clean test tubes, adding various reagents in the following orderGlucose solutionDistilled waterDNS reagent012345The amount of sugar contained(mg)00.20.40.60.81.0Distilled water(ml)10.80.60.40.20DNS reagent3mlDistilled water(ml)2.5mlHeatingHeat 5 minutes(90°C)CoolingImmediately with the flow of cold water to coolOptical density(OD)0.761.0861.5222.0532.7833.342Results: Mix the above solution, each tube after the photoelectric colorimeter (510 nm) for colorimetric determination of the blank control solut