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Nutrition and Dietetics
NUTR 214
Louise Thibault

Lecture 3 – Vegetables - Webster’s Definition is any part of plant that are used in food - In practice, is edible part of plant, can be raw or cooked. Accompanies main course o Brings colour, flavor and texture to meal (proteins not very colourful) - Seeds tend to have more starch than other vegetables, b/c E needed to grow Classification - Root: Carrots, beets, turnips, radishes, parsnip, sweet potato - Bulbs: onions, garlic, chives, leek, shallot - Stems: Celery, asparagus, Anise (fennel) - Leaves: spinach, lettuce, collard, parsley, kale, watercress, bok choy - Seeds: beans, corn, peas, lentils - Flowers: Broccoli, Cauliflower, artichoke - Tubers: potato, ginger root - Cruciferous: group of veg that have protective effect against cancer (anti-oxidant) o Broccoli, brussel sprouts, cabbage, cauliflower, kale, mustard greens, rutabaga, turnips - Legumes: member of plant family leguminosae; characterized by growing in pods o Excellent source of proteins, fiber, iron, complex carbs o Dietary staple o Soybeans (relatively high in fat): used to make textured vegetable protein, meat analogs, tofu, fermented soy  All AA except methionine  best source of protein in vegetables - Fruits: part of plan that contains seeds; mature ovaries of plants; derived from flowers o Avocado, cucumber, eggplant, okra, pepper, pumpkin, squash, tomato, snap beans o Botanically fruits, but composition closer to real vegetables than fruits = VEG Nutritive Value Amount Exceptions & Notes Calorie Low Beans (lots of starch), peas, potatoes, soy beans (legumes) Fat Low Soy Beans, corn, peanut Cholesterol None Phytosterols don’t act like cholesterol. Veg lowers chol Proteins Not good source of Hqual Soybean has all AA except Methionine Carbohydrates Good Potato and corn have high starch, fruits have simple carbs Veg: ripening = sugar  starch. Sweeter if earlier harvest Fruit: ripening = starch  sugar. Ripe melon sweeter Fiber Rich Lettuce not a lot Vitamins Vit C (sprouted beans) Oxalates in veg can bind to Ca, Zn, Fe = dec absorption Riboflavin (B2) Beta carotene Iron Vit K Folic Acid Ascorbic Acid Minerals Potassium Canning increases Na Sodium High in Organic Acids. When boil, can leak into water = Organic Acids colouring, taste and smell Phytochemicals Allicin (garlic, onions) Carotenoid = ProVitamin A. 6µg ß-carotene = 1µg Vit A Carotenoids Plant Cell - Cell Wall: contains fibrous compounds that are indigestible by humans; very sturdy o Fiber includes: cellulose, pectic compounds, hemicellulose: intra and intercell cement (firmness and elasticity characteristic)  Lignin: non-carb, when plant ages, increase concentration = tougher  Gums: polysaccharide that can absorb water and swell several times in size Composition – dependent on which part of plant - Leaf: actively metabolizing section; large amounts of water 91-96% (b/c less carbs) - Stem: good source of vitamins, minerals and cellulose (good for GI, absorbs water, makes bulk) - Roots and Seeds: Storage for CHO and proteins  high amounts of starch Cooking Vegetables: - Dry Heat vs Moist Heat o Dry: baking, roasting, sautéing, deep frying  generally less nutrient loss o Mois: simmering, steaming, braising, microwaving  lots of nutrient loss into water  Microwave is exception, won’t leach - Minimizing Water Loss: o Cut into larger pieces o Using as little as water o Cooking to just before donness o Leave on skin o Fat-soluble vit (ADEK) more stable than water-soluble - Heat-Induced Changes: o Softening of cellulose and texture + breakdown of hemicellulose  Ca to reduce turgor pressure by combining with pectic substances and becoming insoluble = firming food’s texture  If add alkaline (baking soda), = more breakdown = mushy texture o Gelatinization of starch: Ca to reduce. Often canning process is heated to sanitize so compensate by adding Ca  Ca can come from: molasses, hard water, brown sugar o Hydrolysis of pectic substances and cell separation o Destruction of proteins in membranes  fine because not good source of proteins anyway  But soybeans MUST be cooked = some proteins lost o Denaturation of microorganisms and harmful substances o Change in Flavour  To retain: use minimal H 2 and time  Degorge: use salt (osmotic) to draw out bitter substances. Draws out water = Vit too o Ascorbic Acid: oxidated and leached. Vit C oxidized in potatoes as well o Vitamin A: isomerization (trans to cis) = less bioavailable. So needs more ß-carotene now  Colour good indication of isomerization  if water is orange cooking carrots o Odors: unpleasant odors come from sulphur compounds (organic acids) in cruciferae family allium genus (onions, garlic, shallots, leaks, chives)  Odorless until cut or bruised  activates enzyme to create sulphur compound  Reduced by adding vinegar or reducing cooking time o Nutrient Retention: cook with as little water as possible and leave skin on o Colour: fat and water-soluble pigments affected by heating and pH  If cooked in certain way or with certain ingredients, can prevent colour change Storage - Post-harvest respiration rates differ = different rates of deterioration - Water in vegetable no longer bei
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