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) – 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

• 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

Where to find composition information

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

• 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• 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 constantsupply

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

• 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 selectedbeverages

Club soda 100%Iced tea 100%Light beer 95%Beer 92%Cola 89%Orange juice 88%Red wine 88%Vodka (90 proof) 62%

From Murano, UnderstandingFood Science & Technology (2003).

from: Murano, P. “Understanding Food Science and Technology”, Wadsworth, 2003.