Transcript Food categories and composition information

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 MyPlate (2011)
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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 NutritionData.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
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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
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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
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Histidine
Isoleucine
Leucine
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, peas, 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
• pH = 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 pH 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
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No one category
Main ingredient is water
Alcohol
Sweeteners
– sucrose, high fructose corn
syrup, artificial
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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%
100%
95%
92%
89%
88%
88%
62%
From Murano, Understanding
Food Science & Technology
(2003).
from: Murano, P. “Understanding Food Science and Technology”, Wadsworth, 2003.