Colour
Pigments (1)
Pigments (2)
Synthetic Colorants
Analyzing Colour from Spectra
100
Colours we see are __________ by an object.
Reflected
100
Which pigment is necessary for photosynthesis?
Chlorophyll
100
Which is the most widely occurring pigment in plants?
Anthocyanins
100
What is the purpose of artificial ingredients?
They provide colour and flavour
100
In what region does the wavelength of visible light lie?
400nm-700nm
200
What are dyes?
Synthetic food-grade water-soluble substances that are added to produce colour
200
Which colours are Anthocyanins responsible for?
Pink, Red, Purple, Blue
200
State a factor that affects colour
pH
200
Why have dyes used in the past been withdrawn?
The have been found to be carcinogenic
200
Which coloured lights have the highest and lowest energy?
Red (highest) Blue (lowest)
300
What are pigments and where are they found?
Natural colorants which are found in the cells of plants and animals
300
What type of reactions can modify colour?
Oxydative Reactions
300
Which pigment is responsible for the colour of live lobsters?
Red Astaxanthin
300
What are E-numbers?
Numbers given to food additives so that they can be identified
300
Why do chlorophyll a and chlorophyll b not appear the same shade of green?
Light is being transmitted in the 500-550nm region, but the exact values are different
400
What is the complementary colour of blue-violet, and why is that colour seen?
Yellow. White light absorbs the blue-violet wavelength energy and the colour that is remaining (yellow) will be transmitted
400
What is myoglobin?
a red protein containing heme that carries and stores oxygen in muscle cells
400
Why do lobsters turn red when cooked?
The extreme heat breaks double bonds which causes electrons to move to a lower energy level and transmit a different colour
400
What do E-numbers not take into account?
Different countries have different regulations. Some dyes that are permitted in some countries are banned in others
400
What are the common parts of chlorophyll a and chlorophyll b?
long hydrocarbon tail, and hydrophilic porphyrin ring
500
What is the colour of food determined by?
Substances in food that absorb different wavelengths of light
500
What pigment does lettuce have that may have made it orange if the amount of chlorophyll was not so high?
Carotenoids
500
What is the difference in structure between carotenoids and astaxanthin?
Double bonded oxygen present in astaxanthin
500
Why is there a need for International Legislation on Colorant Legislation?
To bring all countries onto equal terms involving the regulations against certain dyes
500
Chlorophyll a can transfer light energy to ______ ______ reactions of photosynthesis
Carbon Fixation
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