food tests Flashcards
steps to prepare food samples
- crush with mortar and pestle
2.add crushed food to distilled water and stir - filter out solid food to get a liquid sample
which test tests for sugar
benedict’s test
benedict’s test only works with _______ sugars
reducing
when testing for sugar, how much of the liquid food sample is added to a test tube
5 cm^3
when testing for sugar, what temperature must the water bath be
75 degrees celsius
when testing for sugar, how much benedict’s solution is added to the sample?
10 drops
when testing for sugar, how long is the test tube left in the water bath for?
5 minutes
when testing for sugar, what is the test tube held in when in the water bath
a test tube holder
if no sugar is present, what colour is the benedict’s solution?
stays blue
what colour does benedict’s solution change to when sugar is present
green, yellow or brick red depending on sugar concentration
what is the carbohydrate food test?
the iodine test
how much food sample is used when testing for starch?
5cm^3
when testing for carbohydrates, what colour is the result of no carbohydrates being present
the iodine solution remains brown
when testing for carbohydrates, what must we do after adding iodine solution
shake the sample
what colour is a positive result when testing for carbohydrates?
iodine solution turns blue-black
what is the test for proteins called?
the biuret test
how much food sample is added when testing for PROTEINS
2cm^3
when testing for protein,how much biuret reagent is added to the food sample?
2cm^3
what is the result of proteins not being present in a food test?
biuret solution remains blue
what is the result of proteins being present in a food test
biuret solution turns pink-purple
how to test for lipids?
ethanol test
when testing for lipids, ethanol solution is added to food sample and…
shaken
what happens if lipids are present after the ethanol test?
solution turns cloudy
