Food
Chemistry information and links
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
Vitamins
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
