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Module 8: Food Chemistry, Nutrition, and Traditional Foods Food: Any substances that can be metabolized by an organism to give energy and build tissue Types: Carbohydrates, Proteins, Fats & Oils Others: Vitamins, Minerals, Salts Molecules of Food: Carbohydrates 6-C rings, 5-C rings Mono-saccharides (sugar, fructose) Dissacharides (lactose, sucrose) Polysaccharides (starch, fibre, glycogen) Carbohydrates are assimilated in the body as “mono-saccharides” following digestion Glucose: Body’s Primary Fuels Lactic Acid + ATP + H2O Glycogens (Branched polymers for short-term storage in liver) Glucose (anaerobic) (monomers) (soluble) Pyruvic Acid CO2 + H20 + ATP (aerobic) •Glucose level in blood stream is highly regulated •Aerobic respiration is releasing 90% of the energy stored in glucose Glycogen Anaerobic Metabolism Aerobic Metabolism Pyruvic Acid CO2 + H20 + 32ATP Molecules of Food: Lipids and Fats Fats: Large biological molecules, diverse compositions, insoluble in water (i.e. non-polar in nature) Types: – – – – Fatty acids (assimilable form) Triglycerides (in blood) Phospholipids (cell membranes) Sterols (e.g. cholesterol) Roles: – Source of energy (during sustained activity) – Structure of cell membrane Free Fatty Acids (one chain) • Saturated • Unsaturated (e.g. Omega-3, Omega-6) Fatty Acids • Long-chain fatty acids (12+ carbons) are abundant in meats and fish • Short-chain fatty acids (12 carbons or less) are abundant in dairy products • Cold-water fish are rich in essential omega fatty acids • Unsaturated fatty acids, when cooked, change conformation to a “trans” shape (which tend to accumulate in blood vessels) • Unsaturated fats are more prone to react with oxygen, causing rancidity (common in stored fish) Triglycerides Phospholipids • Phospholipids are “modified” triglycerides where one fatty acid chain is replaced by a phosphate group • Soluble in water • Important in cell membrane Phospholipids Sterols • Multiple rings of carbon • Best-known sterols: cholesterol (the building block for all other sterols) • Bile acids, some hormones, Vitamin C Sterols Cholesterol Sitosterol (the most abundant and common plant sterol) Absorption of Lipids • Fat breakdown occurs in intestines • Smaller units: fatty acids, glycerol, and sterols • Cholesterol and triglycerides are non-polar, hence need “lipoproteins” to carry them in the bloodstream Molecules of Food: Proteins • Chains of Amino Acids • Diverse roles: enzymes, hormones, regulators, molecular transports, antibodies, building tissue like muscles, and energy • Made up of C, H, O, N, other ions Amino Acids • Four components around a central carbon (C) • One hydrogen • An amino group (NH2) • An acid (-COOH) • A functional group Glycine Amino Acids Essential Amino Acid: Leucine Non-essential Amino Acid: Asparagine Molecules of Food: Vitamins • Essential organic compounds to ensure proper metabolism • Little caloric value • Water-soluble vitamins (enter directly into bloodstream) • Fat-soluble vitamins (must be transported by carrier proteins) • Several diseases are associated with vitamin deficiencies Caloric Contents of Food Molecules Food Type Caloric Content (Cal/g) Fats and Oils 9 % Recommended Caloric Intake 30 Carbohydrates 4 58 Proteins 4 10 Vitamins Trace Not Applicable Subsistence Food Provisioning • Nutrition for indigenous people in the Arctic is changing rapidly; from 100% to <50% “country food”. • Presence of larger communities, presence of “Coop” or “Bay” stores, and an increasing cash economy contribute to changes in feeding habits. • Lastly, hunting activities are costly when modern technologies are used the “pay off” of traditional food provisioning is decreasing. Concepts Subsistence activities: The hunting, fishing, and gathering of local foods for consumption, sharing, and trade or barter. e.g. caribou, whales, seals, marine birds, waterfowls, eggs, fruits (largely a carnivore diet) Note: Commercial trapping or fishing is generally not viewed as traditional food gathering; although they could be traditional activities. Example of Subsistence Food Economy Inupiat households in Barrow, Alaska Production vs. Sharing • Food provisioning is crucial, but sharing is an intricate part of subsistence • Sharing touches upon all members of a community, and represents a way of establishing and maintaining ties to family and within the community at large (e.g. support of elders, non-hunting members) • Sharing is viewed as part of the “culture” of indigenous society Quality Food: Arctic Char Body Part Meat Skin Head Eggs Protein, B Vitamins Protein, Vitamin C, Fat, Iron, B Vitamins Excellent Source (25% or more of daily need) Protein, Iron Protein, Iron, Calcium, Fat Good Source (1524% of daily need) B Vitamins Calcium Fair Source (5-14% of daily need) Vitamin C Vitamin A, Fat, Iron Calcium Quality Food: Beluga Body Part Meat Blubber Skin Excellent Source (25% or more of daily need) Iron, Protein Fat Protein Good Source (15-24% of daily need) Fair Source (514% of daily need) Protein, Omega3 fatty acid Fat Iron Fat, Vitamin A Quality Food: Caribou Body Part Meat Blood Liver Excellent Source (25% or more of daily need) Protein Iron Protein, Iron, Vitamin A Good Source (15-24% of daily need) Iron, B Vitamins Protein Fair Source (5-14% of daily need) Fat, Calcium B Fat, Vitamins Calcium Bone Marrow Stomach Contents Fat Fat Iron, Fat Iron, Vitamin A Iron Protein, Fat, Vitamin A Protein, Fat, B Vitamins, Calcium Protein Quality Food: Muskox Body Part Meat Excellent Source (25% or more of daily need) Protein, Iron Good Source (15-24% of daily need) B Vitamins Fair Source (514% of daily need) Vitamin C Quality Food: Polar Bear Body Part Meat Blubber Excellent Source (25% or more of daily need) Iron, Protein Vitamin A, Fat Good Source (1524% of daily need) Fair Source (5-14% of daily need) Omega-3 fatty acid Fat Iron, Protein Quality Food: Ring Seal Body Part Intestine Liver Blubber Meat Brain Eyes Excellent Source (25% or more of daily need) Protein Iron, Protein, Vitamin A Fat, Vitamin A, Omega-3 fatty acid Iron, Protein, B Vitamins Iron, Protein Vitamin A, Protein, Iron Good Source (15-24% of daily need) Iron Vitamin C Iron, Vitamin C Fair Source (514% of daily need) Fat Fat Protein Fat Fat What is special about a subsistence diet in the North?