NUFS 100 - Topic 2 Food Chemistry

how is food, food?

why are foods high in moisture

come from biological things like plants and animals

what is food a mixture of?

carbohydrates, fats, water, protein, and miscellaneous atoms (ash)

what are some complex organic molecules?

carbon, hydrogen, nitrogen, oxygen

5 major chemical compounds in food

lipids, carbs, protein, water, minerals/ash

what does fat make when it oxidizes?

prefatty acids

What does proximation do?

implications for shelf life

foods must align with legal definition

directs processing parameters

determine energy in foods (caloric content)

always expressed in percentages

True or false: you can not remove all the water in a food?

true. Molecules really like the water and can not let it go, so there will always be some water in a food no matter what

How to find Kcal

multiple by the macronutrients by proximation

What are the macronutrients in Carbs, Protein, Fat, and alcohol?

carbs - 4

protein - 4

fat - 9

alcohol - 7

What do carbohydrates do?

Hydrates carbon (Cn (h2o) n)

source of energy and fiber

monosaccharides

pentoses (5 chain) and hexoses (6 chain)

glucose, fructose, galactose

Disaccharides

Two monosaccharides linked.

sucrose

aka table sugar is glucose and fructose

lactose

glucose and galactose.

too power for isabelle

maltose

glucose and glucose

function of sugar in food

crystalizes

provide body and mouth feel

preservation effect

source of food for yeast

hygroscopic

browning reaction

Millard reaction

reducing sugars and amino acids ie toast

caramelization

lose moisture, sugars decompose and create polymers

oligosaccharides

combination of 3 or more monosaccharides

polysaccharides

long chains of oligosaccharides: starch cellulose, pectin and some hydrocolloids

complex carbs are added to food to:

increase fibber

thicken foods

form gels

bind water

stabilize proteins

straches

long chains of glucose linked together (500-100,000)formed by two different molecules (amylose and amylopectin) , each different

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amylose

linear chains, gel formation

amylopectin

branched chains, viscosity

cellulose

major component of cell walls

long chains of glucose linked together (1-4)

dietary fiber

Pectin

functions as an intercellular cement in fruits and veggies

gelling agent in foods

dietary fiber

Gums

thicken and stabilize food products

xanthan, agar, guar gum etc

dietary fibre

carbs not digested by humans

high fructose corn syrup HFCS

a development in the industry

derived from glucose and hydrolyzed by corn starch

developed in the 50s refined in the 70s, in food since 75

true or false:

every component in complex carbs must do everything it is capable of

false

amino acids

builiding block of protein ( 20 amino acids)

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The shape and function of the protein is determined by the..

amino acid

true or false:

a protein does not need to be broken down to be absorbed

false

4 types of protein structures

primary

secondary

tertiary

quaternary

true or false:

denaturation affects the primary structure

false

denaturation

small changes have a big effect; cooking egg

primary structure

the sequence of a chain of amino acids

secondary structure

occurs when the sequence are linked by hydrogen bonds

include: alpha helix, beta-pleated sheet

tertiary structure

occurs when certain actions are present between the alpha helix and beta-pleated sheets

Quaternary structure

a protein consisting of more than one amino acid chain

involves noncovalent association of protein chains

protein chains may or may not be identical

Function of proteins in foods

emulsifiers

colours; through millard reaction

texture control - thickening, binding, gelling agents

flavour generation - savoury

proteins precipitate at their _____ point

isoelectric

isoelectric

the ph where there is no net charge

what precipitates to make curd and whey

casein

fats appear solid at ____ temp

room temp

oils are ___ at room temp

liquid

lipids are mainly…

triglycerides

true or false:

lipids are not present in monoglycerides

false.

they are present in monoglycerides, diglycerides, and free fatty acids

carotenoids

make food appear a yellow or orange colour

chlorophyll

make food appear green

structure of fatty acids esterified to _____ determines fat properties ie melting point

glycerol

determinates of faty acids

4-28 carbon atoms

saturated vs nonsaturated

cis vs trans orientation around double loom 67

function of lipids in foods

nutrients

texture and mouth feel

flavour

heat transfer

emulsifiers - bind immiscible food components

hydrolytic rancidity

free faty acids are liberated when fat and water interact

oxidative rancidity

reaction across double bands of fats and oxygen.

long chains are degraded

shorter chains are released and odorous

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what types of food are effected by rancidity most

food with high fat contents

water is a growth parameter for ___

microbes

lettuce is what % moisture

96

we remove water to:

inhibit microbial growth

prevent chemical reactions

how we remove water?

freezing - stopping water

drying - removing moisture

addition of salt or sugar

thermal processing

Function of water in foods

flavors, minerals, and vitamins can be dissolved

lubricates as you chew and swallow

texture

facilitate heat transfer - in brine (canned)

facilitates microbial growth

facilitates freeze concentration

true or false:

not all water is available for microbial growth

true

water activity

tells how much water id available for chemical reaction and microbial growth

water activity close to __ is low

0

water activity close to __ is high

1

Bacteria grows at a water activity of

0\.85

yeast grows at a water activity of

0\.68-0.80

mold grows at a water activity of

0\.65

measurement of water activity formula

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free water

can be extracted by a food easily by cutting or squeezing

bound water

can not be extracted easily

can not be used as a solvent for salt and sugar

can be frozen at temps lower than the water freezing point

molecules can not escape as vapour

Pw is known because of the relationship between…

water and temperature

true or false:

vitamins and minerals do not contribute to energy

true

why are vitamins and minerals called trace or ash

there is so little there is a trace amount

vitamins and minerals can be removed and added through..

fortification

thermal processing reduces vitamin _

C

true or false:

vitamin and mineral content can not be altered

false

flour milling to reduce bran and germ reduces vitamin _

B