food tests- 1.3

malnourished definition

to describe people that do not have a balanced diet

the 7 food groups

-carbohydrates

-protein

-fats

-fibre

-minerals

-vitamins

-water

reagent for starch

iodine solution

method for testing for starch

add iodine

colour change when starch is present

yellow-brown ——> blue-black

reagent for sugar

benedict’s solution

method for testing for sugar

add benedict’s solution to the food and heat in a water bath

colour change when sugar is present

blue ——> brick red precipitate

reagent for protein

biuret solution

method for testing for protein

add biuret solution the the liquid food sample and mix

colour change when protein is present

blue to purple

reagent for fat

ethanol reagent and water

method for testing for fat

mix the fat with ethanol and add an equal volume of water

colour change when fat is present

colourless to white emulsion

use for carbohydrates

energy source

simple sugars in carbohydrates

glucose and lactose

complex carbohydrates

cellulose ( plant cell wall)

glycogen (animal)

starch (plant)

what is starch broken down into during digestion

glucose

molecule we need for respiration

glucose

the main constituent of fibre

cellulose from plant cell walls

elements in carbohydrates

carbon, hydrogen, oxygen

use for fat

-energy store (double the energy pergram compared to carb and protein)

-insulation

-protects internal organs

what does fat turn into when digested

fatty acids and glycerol

fat molecule

elements in fat

carbon, hydrogen, oxygen

use for protein

-growth and repair of cells

-energy when reserves of carb and fat are low

what does protein turn into when digested

amino acids

elements in protein

carbon, hydrogen, oxygen, nitrogen

sub-units of carbohydrates

sugars (glucose)

sub-units for fat

fatty acids

glycerol

protein sub-units

amino acids

the amount of energy you need is based on these factors

• activity levels

• age

• gender

• pregnancy

obesity happens when?

having a higher intake of energy than used in excercise

3 variables for burning food practical

• volume of water

• distance between food and test tube

• burn food completely

• stir water before reading final temp

reasons why burning the food is unreliable

• some heat escapes in the air

• some heat absorbed by glass

• food isn’t completely burnt

ways to improve the accuracy of burning food practical

• add insulation

• add oxygen for complete combustion

reasons why using a calorimeter is more accurate

• stirrer (evenly distributes heat)

• insulation (keeps heat in)

• heat transfer coil (directly heats water)

• oxygen (complete combustion)

• crucible (food can’t drop)