Ppt0000009 - Pass the sugar..Honey ! Chemical methods:...

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Unformatted text preview: Pass the sugar..Honey ! Chemical methods: total CHO and reducing sugars Enzymatic methods: glucose & total starch Gravimetric method: total dietary fibers Chromatographic methods: HPLC & GC Concentrated sulfuric acid dehydrate CHO to form aldehydes Aldehydes condense with themselves and phenols to form polymers with yellow- orange color Absorbance @ 490 nm Phenol-sulfuric acid method: total carbohydrates Analyze all sugars: mono, oligo and polysaccharides A standard curve should be ran using standard sugars in the same proportions as they are present in food. Example: In potatoes , glucose and fructose are present in a 1:1 ratio, therefore prepare a standard in the same proportions. Concentrations in samples shall fall onto your calibration curve (Dilute if needed) Reducing sugars reduce Cu 2+ to Cu + in the presence of NaOH. Cu + turns the colorless Ammonium molybdate into blue color (Molybdenum blue) Absorbance @ 520 nm, glucose as standard Somogyi-Nelson method: total reducing sugars Glucose oxidase-peroxidase method H 2 O 2 H 2 O O C H 3 N H 2 O CH 3 NH 2 N H O C H 3 NH O CH 3 + + H 2 O 2 H 2 O O C H 3 N H 2 O CH 3 NH 2 N H O C H 3 NH O CH 3 + + Peroxidase o-Dianisidine Colorless Oxidized o-Dianisidine Brown Use Glucose as a standard One-touch Glucose meter Disposable test strips contain glucose oxidase Require 0.3 -1 l blood (less than one drop) Give a reading within 60 second...
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This document was uploaded on 03/03/2011.

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Ppt0000009 - Pass the sugar..Honey ! Chemical methods:...

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