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Vitamin Analysis

Food Analysis Final Exam

Define vitamin. A low molecular weight organic compound required by humans in small amounts for normal metabolism.
Name three units which vitamins can be expressed in. International units (IU), United States pharmacopeia (USP) units, % daily value (DV)
Which vitamins are water soluble? CB
Which vitamins are fat soluble? ADEK
T or F: It is possible to analyze all vitamins by one technique. False
Name three analytical methods which can be used for vitamin analysis. Bioassays, microbiological assays, chemical assays
Which vitamins can bioassays analyze? D, B12
Which vitamins can microbiological assays analyze? niacin, folate
Which vitamins can chemical assays analyze? A, E, C, thiamin, riboflavin
Name three sensitivities to vitamins. light, oxygen, pH, heat
Name four methods of vitamin extraction. heat, acid, ,alkali, solvent, saponification, enzymes
_____ methods are used in bioavailability studies. Bioassay
Describe how vitamin D bioassay methods are completed. Measure bone calcification after feeding animals known and unknown amounts of Vitamin D; "line test".
Describe the principle behind microbiological assays. The growth of microorganisms is proportional to their requirement for a specific vitamin.
Trienzyme digestion is the AOAC method used to determine amounts of _____. folate
Normal phase HPLC and UV detection are methods used to determine amounts of vitamin ___ (along with saponification and extraction). A
Normal phase HPLC and fluorescence detection are methods used to determine amounts of vitamin ___ (along with saponification and extraction). E
Describe how vitamin C is analyzed. L-ascorbic acid is oxidized, and a drops of dye are added in excess until appearance is pink; the volume of dye used is correlated to the amount of vitamin C.
What should be done is a vitamin C sample is colored? Change absorbance to 545 nm,
T or F: The pink endpoint method measures both forms of ascorbic acid. False
T or F: The microfluorometric method measures both forms of ascorbic acid. True
Describe how thiamin is analyzed. After extraction with heat and acid, sample is enzyme hydrolyzed and oxidized to thiochrome before measured for fluorescence.
Describe how riboflavin is analyzed. After extraction with heat and acid, interfering material in sample is oxidized and fluorescence is measured.
Created by: goberoi
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