- Slides: 17
Food categories and composition information • 14 categories defined by USDA as “commodities” – red meat, poultry, fish/shellfish, eggs, dairy, beverage milks, fats/oils, fruits, vegetables, peanuts/tree nuts, flour/cereal products, caloric sweeteners, coffee, cocoa – these include some processed foods • Food Guide Pyramid (1992) defined 6 categories from a nutritional pov – now 5 with My. Plate (2011) – – – Bread, cereal, rice, pasta (grains) Fruit group Vegetable group Milk, yogurt, & cheese group (dairy) Meat, poultry, fish, beans, eggs & nuts group (protein) Fats, oils & sweets (no recommendation)
Food Guide Pyramid (1992)
New for 2011 at: http: //www. choosemyplate. gov/food-groups/ New nutritional guidelines: five categories recommended for balanced daily consumption Can click on each category for description of what’s included, how much to eat, health/nutritional benefits
Where to find composition information • Composition of recognized nutrients in a given food/beverage can be found in USDA National Nutrient Database http: //www. nal. usda. gov/fnic/foodcomp/search/ • To search the content of specific constituent across many foods, access nutrient lists at: http: //www. ars. usda. gov/Services/docs. htm? docid=22114 • Databases on certain foods like flavonoids that are extensively researched are re-released periodically: http: //www. ars. usda. gov/Services/docs. htm? docid=6231 • Manufactured products are required to use “Nutrition Facts” labeling • Data given per serving • Total fat, carbohydrate, protein, cholesterol, sodium, vitamins & minerals by weight & RDA • May list other constituents but not a complete list
Where to find composition information • Searchable nutrition facts database for produce and products at http: //www. nutritiondata. com/ • For more specific information on phytochemical composition • USDA databases (recognized nutrients) • Scientific literature (all phytochemicals) – AGRICOLA database (link from UMD library site), can search National Agricultural Library – Scifinder Scholar database – searches CAS online for chemistry literature – Pubmed – studies on health/nutrition – Journal of Agricultural and Food Chemistry
Nutritional & Health Studies and Industry News • Nutraingredients-USA: nutrition & supplements news (http: //www. nutraingredients-usa. com) • Food Navigator: food & beverage news Europe(http: //www. foodnavigator. com/) USA (http: //www. foodnavigator-usa. com/) • Can search by topic, ingredient, health conditions
2 slices Domino’s deep-dish cheese pizza, as reported by Nutrition. Data. com
A word about organic foods • Certification requirements and farming practices vary worldwide but generally – Grown without synthetic pesticides/herbicides or fertilizers – Processed without irradiation or “chemical” food additives – Not genetically modified – For animal products, pesticide-free feed and no antibiotics or growth hormones
But are organic foods better for you? • 2012 study: Smith-Spangler, et al, Annals of Internal Medicine 157: 348 -366 • Meta-analysis of 17 human and 223 studies of nutrient & contaminant levels in foods between 1966 and 2011 • Conclusion: published literature lacks strong evidence that organic foods are significantly more nutritious, but they may reduce exposure to pesticide residues and antibiotic-resistant bacteria.
Natural food constituents classified by chemistry & physiological roles • Carbohydrates – energy storage • Lipids (fat/oil) – energy & structural • Amino acids and proteins – structural & regulatory – Lipoproteins, glycoproteins, etc…specialized roles • • Water Vitamins and co-factors - catalysis Minerals Plant secondary metabolites or “phytochemicals” – Roles in plants are many – defense, propagation – Can be classified into subcategories based on biosynthetic pathway and structure – structural similarities exist among members of a genus (e. g. Vaccinium berries)
Cereals, grains • • Corn, rice, wheat, barley, rye, oats, millet, sorghum, etc Kernels (seeds) used (endosperm, bran & germ) http: //www. choosemyplate. gov/food-groups/grains. html Contain primarily carbohydrates – simple sugars – disaccharides – polysaccharides: amylose/amylopectin (starch) and cellulose (undigestible = fiber) – Fiber may be insoluble or soluble in water, structurally complex molecules – Ratio of simple: complex carbs varies • Protein, fat and mineral content varies – Vitamins/minerals may be added back if lost in processing • Plant proteins are generally deficient in lysine & methionine from: Murano, P. “Understanding Food Science and Technology”, Wadsworth, 2003.
Essential amino acids • • • Histidine Isoleucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine Cannot be synthesized by human body, therefore must be included in diet “Complete proteins” Body doesn’t store a. a. ’s to a great extent, needs constant supply from: Murano, P. “Understanding Food Science and Technology”, Wadsworth, 2003.
Meat, poultry & seafood • It’s got a lot of protein and saturated fat but it can be tasty • Furnishes all of essential amino acids • B vitamins, iron & other minerals too. • Seafood is a bit more interesting from a health p. o. v. due to omega-3 fatty acid content in some fish…stay tuned! from: Murano, P. “Understanding Food Science and Technology”, Wadsworth, 2003.
Fruits & vegetables • What’s the difference? Sugar content? • Botanically speaking, a fruit is the ripened ovary of a plant, contains the seeds • A vegetable is any other edible plant part: leaf, shoot, root, tuber, bulb, flower or stem • Tomatoes & squash are fruit! • Composed mainly of water, carbohydrates, but high in vitamin content (esp. A & C) • Secondary metabolite/phytochemical content is diverse • USDA website lists categories of fruits and vegetables, some health benefits – http: //www. choosemyplate. gov/food-groups/vegetables. html – http: //www. choosemyplate. gov/food-groups/fruits. html from: Murano, P. “Understanding Food Science and Technology”, Wadsworth, 2003.
Legumes & nuts • Legumes are edible seeds, pods of certain flowering plants – Mainly from families Leguminosae, Fabaceae – Beans, lentils, soybeans, peanuts • Tree nuts – Are actually fruits – Include almonds, walnuts, pecans, macadamias, etc. from various families • Both legumes and nuts – Have a high protein content compared to other plant-based foods (common nuts range from 8 -38 g protein/cup) – Legumes are deficient in lysine – Carbohydrate composition may contain substantial fiber – Good source of minerals – Nuts are higher in fat, but mainly unsaturated from: Murano, P. “Understanding Food Science and Technology”, Wadsworth, 2003.
Dairy products • Derived primarily from cow’s milk but some other sources as well • Whole milk composition = 88% water, 3. 3% protein, 3. 3% fat, 4. 7% carbs • p. H = 6. 6, high calcium content • Milkfats primarily saturated but contain fat-soluble vitamins A, D, E, K • Major carb = lactose – intolerance caused by lactase deficiency • Major proteins = casein & whey – casein is coagulated out as curd by lowering milk p. H to 4. 6 with rennin, an enzyme used in cheesemaking – whey proteins can be pptd out by heat, isolated by filtration – whey used as supplement and gelling agent from: Murano, P. “Understanding Food Science and Technology”, Wadsworth, 2003.
Beverages • • No one category Main ingredient is water Alcohol Sweeteners – sucrose, high fructose corn syrup, artificial • o Brix = wt % sucrose – (g sucrose/100 g sample) – measured by refractometry – flavor depends on Brix: acid ratio • Nutrients? • Phytochemicals? Water content of selected beverages Club soda Iced tea Light beer Beer Cola Orange juice Red wine Vodka (90 proof) 100% 95% 92% 89% 88% 62% From Murano, Understanding Food Science & Technology (2003). from: Murano, P. “Understanding Food Science and Technology”, Wadsworth, 2003.