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10 - Vitamins - Vitamins March 3-10 2010 Ascorbic Acid...

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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
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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
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