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How to prevent enzymatic reactions in fruits and vegetables GCSE coursework
- Institution
- GCSE
This coursework is about the different ways you can prevent and slow down enzymic reactions in fruits and vegetables.
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Aliya HussainFood preparation and nutrition coursework
Chosen task: Investigate the ingredients and methods to prevent enzymic
browning and oxidation when preparing fruit and vegetables.
Task analysis: I want to carry out investigations to find which ingredients and
methods prevent enzymic browning and oxidation. To investigate I will be using
different fruits and vegetables that go through enzymatic browning, for example,
apples, bananas, grapes, avocados, lettuce and aubergines. I will be trying out
different methods to prevent enzymic browning and oxidation and see which
method is the most effective.
Aim: my aim is to see which methods and ingredients work best at preventing
enzymic browning.
Prior learning - enzymic browning and oxidation: When a fruit or a vegetable has
been cut the cells get cut open as well, this allows oxygen to react with the cells
resulting in an oxidation reaction. However, because enzymes (biological
catalyst) are found in the cells, when the cells get cut open the oxygen gets in
contact with enzymes which increase the rate of the oxidation reaction resulting
in enzymic browning. There are different methods of preventing enzymic
browning for example, after cutting a fruit or vegetable put it into cold water,
putting an acidic solution on it or blanching.
Process of
enzymic
browning over
https://www.google.com/search?safe=strict&tbm=isch&q=enzymatic+browning&chips=q:enzymatic+browning,g_1:apple:kEKzBEyw9jM%3D&usg=AI4_-
kT2fAztqyfS3dzBuupT8FK1X3vwsg&sa=X&ved=0ahUKEwj1rOeam9_kAhX0sHEKHap2DrcQ4lYIKSgA&biw=1280&bih=907&dpr=1#imgrc=IN_fJFJr15t7CM :
Research: Enzymic browning is a chemical reaction which occurs in fruit and
vegetables by enzyme phenolase. Phenols and the Enzyme phenolase
are found in plant cells. For example, the cells of an apple contain
enzyme phenolase and phenols; when they are exposed to oxygen in
the air the oxygen results in an oxidation reaction. The phenolase
changes the phenols into melanin, which is a brown pigment and gives
fruit and vegetables a brown colour when oxidised.
http://www.food-info.net/uk/colour/enzymaticbrowning.htm
Enzymes are proteins which can seed up chemical reactions and act
structure of as biological catalysts. Enzymes also cause fruit and vegetables to
phenol ripen or over ripen, which gives them a brown colour.
Enzymic browning can be slowed down or prevented, in order to prevent it you
will need to denature the cells, this is because after a cell has been denatured it
can no longer carry out its cellular function, therefore it will not go through an
oxidation reaction and will not enzymically brown. This could be done in many
1
, Aliya Hussain
ways but the two main methods of preventing enzymic browning is by adding
heat or an acid to fruit or vegetable, this is because heat and acid denature the
cells. Lemon juice could be added to stop the enzymes from working properly
this is because lemon juice has a high acidic PH level of 2 and enzymes only
work best at the PH level of 3. Enzymic browning could also be prevented by
adding heat. When the fruit or vegetable gets heated at a high temperature the
enzymes get denatured, which prevents enzymic browning. Putting the fruit or
vegetable in a cold environment could slow enzymic browning down. The cold
environment would slow down the oxidation reaction; this is because enzymes
only react at a fast rate at 37°C so the cold environment would slow down the
oxidation reaction. However the fruit/vegetable will still eventually brown.
Enzymes can be
denatured by
heating them at
a high
temperature or
by putting acid
https://www.google.com/search?q=enzyme+denature&rlz=1C1CHBF_en-GBGB745GB745&sxsrf=ACYBGNRAaunRuoQ25hq_Wi9QBmHjvK-
XtA:1569520561968&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiB8cDch-
_kAhWxSBUIHadIB78Q_AUIEigB&biw=1600&bih=740#imgrc=DY2vwzaPMmmnqM :
Investigation
Aim: My aim is to see which methods and ingredients work best at preventing
enzymic browning.
Hypothesis: My hypothesis is that the most succsessful method of preventing
enzymic browning in fruit and vegetables is going to be blanching because it is
going to denature the enzymes the most.
Investigation: To test my hypothesis I’m going to be doing three investigations
which focus on preventing enzymic browning in fruit and vegetables.
-Investigation 1: soaking fruit/vegetable in different acidic solution- investigation
1 relates to my research because I found out that by soaking fruit and vegetable
in an acidic solution will prevent enzymic browning because the acid in the
solution will denature the emzymes.
-Investigation 2: different methods - investigation 2 relates to my research
because I will be trying out different methods such as blanching, acidic solution,
ascorbic acid and cold environemt and will see which method works best at
preventing enzymic browning.
-Investigation 3: blanching fruit/vegetable for different lengths of time -
investiagtion 3 also relates to my research because I found out that blanching
the fruit and vegetable can prevent enzymic browing because the fruit and
vegetable is put in boiling water and then put in to cold water which denatures
the enzymes therefore preventing an oxidation reaction to take place.
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