Heating Foods and Its Effect on Amoutn of Vitamin C

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Heating Foods and Its Effect on Amoutn of Vitamin C

Aim

The aim of the experiment is to investigate how much Vitamin C /

Ascorbic Acid is destroyed when Orange juice is heated at 80°C for

different lengths of time.

Introduction

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Certain foods contain high concentrations of Vitamin C. When these

foods are heated their ascorbic acid content decreases, this is a

non-reversible reaction.

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During the sterilisation process foods are heated and Vitamin C is

destroyed. In order to maintain the initial concentration, Ascorbic

Acid is added.

[IMAGE]

DCPIP (dichlorophenol-indophenol solution) is a dark blue indicator

that turns colourless when a certain amount of Ascorbic Acid is

detected.

The experiment is to determine the concentration of ascorbic acid

present in five different solutions of orange juice, each of which has

been pre-treated in a different manor as specified in table 1:

Table 1

Solution number

Pre treatment conditions

1

Heated at 80°C for 1 minute

2

Heated at 80°C for 2 minutes

3

Heated at 80°C for 3 minutes

4

Heated at 80°C for 4 minutes

5

Heated at 80°C for 5 minutes

Fair Testing

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* The temperature of a substance affects the rate at which it reacts

with another. This is because the molecules have more kinetic

energy making them react faster. Therefore each test-tube of

orange juice must be cooled to the same temperature (probably room

temperature) before they are tested for their ascorbic acid

content, otherwise the results will be inaccurate.

* Using the same carton of orange juice should ensure that the Molar

strength of each test solution is the same.

* If a stopwatch is used instead of a standard watch to time the 1 -

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