Food Composition (1/11) Flashcards
T/F: all of your food is made of ‘chemicals’
true
What are the most abundant food chemicals?
water, carbohydrates, fat, and protein
What is bound water?
water that is already involved with other stuff in the food so it won’t participate in other reactions
What is free water?
water that is available to participate in other reactions
What type of measurement allows us to figure out how much water is “free”?
water activity
What does high water activity mean?
food spoils faster
How can we lower the water activity?
dry the food out, freeze it, and add other ingredients such as salt or sugar
Why is water vital in food preparation?
it acts as a solvent, helps with heat transfer, cleaning, chemical rxns, and flavor
What is hard water?
when the water has a lot of ions such as calcium in it
How does hard water change how water works in foods?
hydration of dried things can be slower, differences in pH can change color of foods and can lead to cloudiness in things like tea
How can we change the hardness of water?
using water softeners, distillation, and reverse osmosis
How does water softeners work?
replaces calcium with sodium or potassium. Sodium is more common due to potassium costing more and can make water have a bitter taste
What is reverse osmosis?
uses diffusion and dialysis membranes to remove dissolved ions
What are carbohydrates made of?
sugars
What are monosaccharides?
single sugars
What are examples of monosaccharides?
glucose, fructose, ribose, galactose
What are disaccharides?
two sugars
What are examples of disaccharides?
sucrose, lactose, maltose
What are examples of oligosaccharides?
inulin, human breast milk
What are examples of polysaccharides?
starch, pectin, gums
What is the sugar structure?
a chain of carbons with OH and H attached
What has to be in the structure to be a sugar?
one carbon must be doubly bound to oxygen or the chain can convert to a ring where the carbon is single bound to two oxygens
How do we get energy from larger carbohydrates?
by enzyme digestion
What are examples of digestible carbohydrates?
sucrose, maltose, and starch
What are examples of not digestible carbohydrates?
cellulose, pectin, oligosaccharides of glucose and fructose, and beta-glucans
How is fiber excreted?
in the feces or digested by bacteria in colon (resulting in gas)
What is carmelization?
sugars when heated start reacting with each other, leading to lots of different types of big molecules, small molecules, and brown things
What is Maillard browning?
sugars reacting with amino acids, creating new molecules that smell nice and are brown
What are fats insoluble in?
water
What are triglycerides?
the form of fat that gives us energy
Which provides more energy per gram, triglycerides, carbs, or proteins?
triglycerides
What is the kcal/g for fat?
9 kcal/g
What is the kcal/g for carbs?
4 kcal/g
What is the kcal/g for protein?
4 kcal/g
What makes up a triglyceride?
3 fatty acids plus 1 glycerol
Whats the difference between saturated fats and unsaturated fats?
saturated fats have no double bonds and unsaturated fats do
What do sterols do?
control how cell membranes work, serve as biological signals to certain parts of the body, and are part of bile
What is the function of fat in food?
used for rapid dehydration cooking, makes foods feel tender, and flavor
What are proteins made up of?
amino acids
Amino acids from the protein can be used for?
making new proteins or broken down for energy
What are the essential amino acids?
isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, histidine
What determines the function of a protein?
the 3D shape made by the amino acids
What does denature mean?
destroying the structure of a chemical, so it no longer has the same function
How does denaturing proteins occur?
with cooking or blending food
What are sources of protein in the human diet?
meats, eggs, dairy, legumes, nuts, cereal grains
What is the protein function in food?
bind water, form gels or foams, thicken, react with sugar for maillard browning, give structure, and enzymes are proteins!
What are solutions?
When two or more things mix at the molecular level
What color are solutions usually?
clear (light passes right through)
What are examples of solutions?
salts in water, sugar in water, and some proteins in water
What are dispersions?
when two or more things are mixed, but on the molecular level
What are the two types of dispersions?
colloids and suspensions
What are colloids?
looks like its completely mixed together, but you might be able to see chucks/droplets under a microscope (opaque)
What are suspensions?
often can see the different particles in this type of mixture (opaque, or clear with floaters)
What are the special types of colloids?
sol, gel, goams, and emulsions
What is sol?
solid dispersed in a liquid
What is gel?
large dispersed molecules trapped in water, forming a solid-like structure
What are foams?
gas dispersed in a liquid or a solid
What are emulsions?
fat and water mixed
Whats the difference between sol vs gel?
sol behaves more like a liquid and gel behaves more like a solid
