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FDSN 507 Midterm 2

Carbohydrate Analysis

Give three reasons why carbohydrates are important. Main source of energy, dietary fiber, provides stability properties, sugar lowers water activity.
Define total carbohydrate. 100 - (moisture + ash + lipid + protein)
Define other carbohydrate. Total carbohydrate - (dietary fiber + sugars)
T or F: Sugars include polysaccharides. False
T or F: Total carbohydrate is always calculated, never measured. True
What are the steps in carbohydrate sample preparation? 1. Dry sample 2. Grind sample to powder 3. Extract lipids via Soxhlet extractor
80% hot ethanol can be used to extract ____. mono-/oligo- saccharides
What method is used to determine total carbohydrate? Phenol-sulfuric acid method
In _____ method, carbohydrates are heated in the presence of furan, which condenses with phenol to form compounds quantified with a spectrophotometer. phenol-sulfuric acid
Name three colorimetric methods for reducing sugar analysis. Somogyi-Nelson, Munson-Walker, Lane-Eynon
Reducing sugar analysis involves reduction of ____ ions in alkaline solution to _____ ions by reducing sugars. cupric, cuprous
What method is used to treat a sample before enzymatic analysis? Carrez treatment
Describe the Carrez treatment. Emulsions are broken, proteins precipitated, and colors absorbed; suspension is filtered and used in assay.
Give two examples of monosaccharides. Fructose, glucose
Give two examples of oligosaccharides. Lactose, maltose, sucrose
Give two examples of polysaccharides. Amylose, amylopectin, starch
Give three advantages to enzymatic methods. Specific for substance being measured, kits available, low detection limits.
Give two disadvantages to enzymatic methods. May have interfering compounds, not always 100% specific
Name two methods for mono- and oligo- saccharide analysis. TLC, capillary electrophoresis
____ can be analyzed by enzymatic methods, degree of gelatinization, or degree of retrogradation. starch
Describe the enzyme method for starch analysis. Starch is converted in D-glucose by enzymes, and then D-glucose is quantified enzymatically; glucose oxidase, peroxidase.
What are disadvantages to the enzymatic method for starch analysis? Amylases must be pure, not quantitative for high-amylose starch.
_____ enzyme is used to determine degree of starch gelatinization and retrogradation. pullulanase, B-amylase
How is pectin content determined? Saponify with NaOH then acidify/precipitate with calcium then weigh pectin; spectrophometric methods
Define dietary fiber. The edible parts of plants resistant to digestion and absorption in the human small intestine with partial fermentation in large intestine.
T or F: Dietary fiber includes monosaccharides. False
Name two types of soluble fiber and what foods it is found in. Pectin, hydrocolloids/gums; beans, fruits and vegetable
Name two types of insoluble fiber and what foods it is found in. Cellulose, ligin; wheat bran and whole grains
T or F: Crude fiber is not used for human food. True
What is the advantage to the AOAC method for total dietary fiber? Includes all fiber components, including resistant starch
What are the disadvantages to the AOAC method for total dietary fiber? Time consuming, overestimates fiber content in foods with simple sugars
Name four physical methods used to analyze carbohydrates. Microscopy, mass spectroscopy, specific gravity, refractometry
Created by: goberoi
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