Assistance for North Carolina Science Teachers

Use the information and links found below to assist in fulfilling your competency goals. To find out if students would be available to come visit your classroom and bring food science to you, please contact Sharon Ramsey

Grade 4 Competency Goal 4:
The learner will conduct investigations and use appropriate technology to build an understanding of how food provides energy and materials for growth and repair of the body.
Objectives
4.01 Explain why organisms require energy to live and grow.
4.02 Show how calories can be used to compare the chemical energy of different foods.
4.03 Discuss how foods provide both energy and nutrients for living organisms.
4.04 Identify starches and sugars as carbohydrates.
4.05 Determine that foods are made up of a variety of components:

There are three main constituents of foods-
Carbohydrates
Lipids
Proteins

There are other minor constituents, including
Inorganic mineral components
and Organic materials, including
Vitamins
Enzymes
Emulsifiers
Acids
Oxidants
Antioxidants
Pigments
Flavors

Water is also a very important constituent.

Below you will find information and links to websites containing information and activities about these constituents.

General lab supplies , solution, reagents, etc.

(no supplier is endorsed...these are typical sources found via the internet).
Commercial equivalents for chemicals from the Science House
General lab chemicals and supplies - Carolina Biological
General lab chemicals and supplies - Science Kit.com
General lab chemicals and supplies - Best Lab Deals.com
General scientific supplies and experiment books- Flinn Scientific Inc.

General Information and Muti-component labs(may contain several experiments)

Institute of Food Technologists k-12 resource site
Food Testing lab (protein, fat, sugars)
Food Lab (many different cool food experiments, not all are food chemistry...)
University of Nebraska Lincoln food chemistry experiments page...very expansive experiments in many areas of chemistry

General Food Chemistry information and definitions from the Univ. of Nebraska

Carbohydrates
Sugars
-usually used for sweetness
-soluble in water and readily form syrups
-form crystals when water is evaporated from their solutions
-supply energy
-readily fermented by microorganisms
-prevent the growth of microorganisms in high concentrations (used as a perservative)
-darken in color (carmelize) on heating
-some combine with proteins to give dark colors in a browning reaction
-give body and mouthfeel to solutions in addition to sweetness
(from Food Science, by Norman Potter. AVI Press, New York
Basic Chemistry of Sugar Ring stuctures
General sugar structure
Oregon State U. Sugars composition and uses
Extensive page of information on sugars (FAQ, papers, links) from Orgeon State
German site for Fehling's Test for reducing sugars (good discussion)
Benedict's test for reducing sugars from Western Kentucky Univ.


Starches
-are not sweet
-not readily soluble in cold water
-form pastes and gels in hot water
-provide a supply of energy
-occur in seeds and tubers as characteristic starch granules
General starch structure
Oregon State starch information page(with links that are more in depth for advanced students)
Starch structure and experiments (really cool graphics) from Elmhurst College
German site with lab for starch using Lugol solution
NC State Science House starch experiment with temperature
Starch test on apples using iodine (Nova Scotia Apple site)

Pectins and carbohydrate gums (from plants)
-made up of chains of repeating units, but units are sugar acids rather than simple sugars
-pectins are common in fruit and vegetables and are gumlike
-pectins are soluble in water, especially hot water
-pectins in colloidal solutions contribute viscosity (thickness) to tomato paste and stabilize the particles in orange juice
-in solutions, pectins form gels when sugar and acid are added (jelly manufacture)
-other carbohydrate gums include gum arabic, gum karaya and gum tragacanth and from seaweed we get agar-agar, carageenan and algin
-act as thickeners and stabilizers
(from Food Science, by Norman Potter. AVI Press, New York)

Lipids
-are not polymers of repeating molecular units
-do not form long molecular chains
-do not contribute structural strength to tissues
-smooth, greasy substances
-insoluble in water
-always has other substances associated with it in natural foods (such as vitamins A,D,E and K, sterols, cholesteral in animal fats, ergosterol in vegetable fats, and phospholipids)
-typical lipid consists of glycerol combined with 3 fatty acids.
(from Food Science, by Norman Potter. AVI Press, New York)
IFT Food Chemistry Lipid experiments and background info- teacher page
General lipid structure from the University of Cincinatti
Howard Hughes interactive site for lipids..great graphics
Advanced information on fatty acids and structure from St. Johns University
Institute of Shortening and Edible Oil site- very complete information on fats and oils
Oregon State Univeristy Lipid site...lots of questions and answers
Case study and experiment with fats and temperature

Proteins
-molecules of protein are made pricipally of carbon,hydrogen, oxygen and nitrogen. Most proteins contain some sulfur and traces of phosphorus and other trace elements
-essential to life
-help form supporting and protective structures such as cartilage, skin, nails, hair and muscle
-major constitutents of enzymes, antibodies and body fluids (milk, blood and egg white)
-built from amino acids which polymerized to form long chains
-amino acids have -NH2 (amino group) and -COOH (carboxyl group) attached to the same carbon atom
-when 2 amino acids combine, a molecule of water (H2O) is eliminated and a dipeptide is formed
-side chains can react with dipeptides to form polypeptides
-20 amino acids
- 8 designated essential amino acids for man (cannot be synthesized by man at adequate rate to sustain growth or health and must be supplied by foods) are leucine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
-can form chains which can be straight, coiled or folded
-chains can be oriented parallel to one another like the strands of a rope or randomly tangled like a bunch of string
-changes in temperature and pH change the conformation of proteins
(from Food Science, by Norman Potter. AVI Press, New York)
The chemistry of Amino Acids resource page
Biuret test (and simple lipid test)
British source for Biuret test
structure of proteins from basic to complex (from MIT)
General inforamtion (including history) of protein
Very basic information on proteins from Kid's Health
How Stuff Works page on Proteins

Leavening Agents
Leaven- a substance used to produce fermentation in dough or a liquid or a material used to produce a gas that 'lightens' dough or batter.
- used to raise baked goods.
-water a leavening agent (pie crusts, some crackers)
-air incorporated into batter (angel and sponge cakes)
- expand when heated and cause the raising of the dough or batter when gas is trapped in matrix of gluten and starch from flour

Yeast
-breads and sweet doughs usually leavened with carbon dioxide produced from yeast fermentation
-Saccharomyces cerevisiae ferments simple sugars and produces carbon dioxide and alcohol
-gradual process that starts slowly and increases rate with time as yeast cells multiply and starch is broken down to form sugar

Chemical agents
-produce carbon dioxide gas
-rapid production, can be instantaneous

Baking Soda
-NaHCO3
-needs moisture and an acid source such as vinegar, citrus juice, sour cream, yogurt, buttermilk, chocolate, cocoa (not Dutch-processed), honey, molasses (also brown sugar), fruits or maple syrup to react
-used to neutralize acids in foods
-around 4 times as strong as baking powder
-can cause soapy flavor in high amounts

all about baking soda from Wikipedia

Single-acting and Double-acting Baking Powders
- NaHCO3 plus acidifier(s) and drying agent (usually an acid salt and cornstarch)
-can cause acidity and/or bitter off-flavor
-single acid salt reaction with soda to create gas when moistened in single-acting
-two acidifiers used in double acting to produce CO2 in two steps, first when moistened, then again when heated
-double-acting is the only commercial baking powder available today

Difference between baking powder and baking soda
Experiment with baking powder and baking soda
Interesting history and facts about baking powder and baking soda

 

Vitamins
Ascorbic Acid (Vitamin C)
-water-soluble organic acid with antioxidant properties
-used in the food industry to prevent browning of fruits and oxidation of fats
-necessary to prevent Scurvy
-important in formation of collagen and in absorption of iron and healing of wounds

General information from Wikipedia
Ohio State Extension fact sheet on Vitamin C and nutrition
Uses for Ascorbic acid in the food industry
Simple explanation of the reactions in the Vitamin C test
Quantitative Vitamin C test procedure

Enzymes
Emulsifiers
Acids
Oxidants
Antioxidants
Pigments
Flavors

Water

Calories
-Calorie - amount of heat required to raise the temperature of 1 gram of water 1 degree Celcius.
-Kilocalorie (1000 calories) is the unit commonly used to represent energy values of foods -or Calorie with a C instead of a c
-not all carbohydrates (or fats, or proteins) yield the exact same amount of energy when burned in a calorimeter, so common averages from studies (in kcal/g) are used
-carbohydrates average 4.1 kcal/gram in a bomb calorimeter, are about 98% digestable and yield 4 kcal/g when consumed
-proteins average 5.7 kcal/g in a bomb calorimeter, are not as easily digested and yield an average of 4 kcal/g when consumed
-lipids average 9.5 kcal/g in a bomb calorimeter, are 95% digested and yield an average of 9 kcal/g when consumed
-fats are the most concentrated source of food calories
-carbohydrates are the cheapest source of calories, proteins the most expensive
(from Food Science, by Norman Potter. AVI Press, New York)
Testing nuts for calorie content
Another test for calories from PBS
Test from Nebraska using a cheese puff and chimney calorimeter

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Last modified on November 10, 2005
Webmaster: Sharon Ramsey