Vitamins
March 3-10, 2010
Ascorbic Acid:
•
Citrus fruits, melons, and strawberries
•
Honey dew, cantaloupe
•
Potato skins (near skin of potatoes)
•
Vegetables
•
Parsley
•
Water soluble and highly susceptible to oxidation
•
Antioxidant = susceptible to oxidation (b/c it’s a reducing agent)
•
Some losses with cooking and processing
•
May leach out into cooking water
•
Some may be oxidized
•
This is why blanching water can be used for soups to retain nutrients
L-ascorbic acid
L-dehydroascorbic acid
- in the original state
- reducing agent
- when it donates H+, it’s in the oxidized form
- will stay stable unless it’s reduced
Vitamin A:
•
Lipid-soluble
•
In a precursor form such a β-carotene in “orange-coloured” crops as well as dark green leafy vegetables
•
Ex. yams, squash, pumpkin, dark green leafy veg
•
Chlorophyll is in dark green leafy veggies
•
Ratio: 6:1 β-carotene to vitamin A due to its insufficient conversions
•
The unique chemical structure allows them to function as antioxidants
•
β-carotene is mostly functional at low oxygen concentrations
o
therefore smokers are breathing in a lot of free radicals, increased oxygen
β-carotene won’t have beneficial functions
•
β-carotene has double bond organization (conjugated double bond)
o
conjugated double bond makes β-carotene good antioxidants
This
preview
has intentionally blurred sections.
Sign up to view the full version.
Vitamins
March 3-10, 2010
Contribution of Edible Plants to Vitamins in the US diet
Group
Vitami
n A (%)
Thiamin
e (%)
Riboflavi
n (%)
Niaci
n (%)
Ascorbi
c acid
(%)
Fruits
Potatoes, sweet
potatoes
Vegetables
Dry beans & peas
Flour (cereal)
7.3
5.7
36.4
Trace
0.4
4.3
6.7
8.0
5.5
33.6
2.0
1.9
5.6
1.8
14.2
2.5
7.6
6.8
7.0
22.7
35.0
20.9
38.3
Trace
0.0
Total (plants)
49.8
58.1
25.5
46.6
94.2
B-Complex Vitamins:
•
Present in moderate amounts in fruits and vegetables
•
Fortified at higher levels in flour
•
Folic acid is important for neural tube defect prevention
•
Moderate amount of B vitamins in fruits & veggies
•
B vitamins are located with bran component of flours & wheats
o
none in all-purpose and cake flour since the bran is removed
o
that’s why in Canada, the flour is fortified
•
flour & cereal products are main contributors to B vitamin in North American diets
Effects of Processing On Colour Pigments
Carotenoids:
•
fairly stable colour
•
includes:
•
β-carotene – orange, yellow colour
•
Lycopene – red
•
Astaxanthin – red (ex. shellfish)
•
some change with processing
o
boiling can affect colour intensity due mostly to a bond geometry
•
Conversion of bond geometry affects intensity of colour
•
Acid – conversion of ‘trans’ to ‘cis’
•
acid enhances bond geometry conversion
•
Trans configuration leads to zig-zag shape

This is the end of the preview.
Sign up
to
access the rest of the document.
- Winter '10
- Y.Yuan
- Enzyme, pH, Redox, Vitamin
-
Click to edit the document details