8. Gelatin is a soluble protein that can be added to different food products - Scottish Highers Chemistry - Question 8 - 2019
Question 8
8. Gelatin is a soluble protein that can be added to different food products.
(a) A structure for a section of a protein chain in gelatin is shown.
(i) State the n... show full transcript
Worked Solution & Example Answer:8. Gelatin is a soluble protein that can be added to different food products - Scottish Highers Chemistry - Question 8 - 2019
Step 1
State the number of amino acids that joined together to form the section of the protein chain shown.
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Answer
The section of the protein chain shown is formed by 6 amino acids joining together.
Step 2
Name the weakest van der Waals' force between water and gelatin molecules.
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Answer
The weakest van der Waals' force between water and gelatin molecules is London dispersion forces.
Step 3
Describe how the student should have made up the solution.
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Answer
The student should have followed these steps:
Dissolve the gelatin: Begin by adding the 2 g of gelatin into a small volume of water (less than 100 cm³) in the volumetric flask.
Transfer quantitatively: Use rinses and washings to ensure that all gelatin is transferred to the volumetric flask.
Fill to the mark: After the gelatin is completely dissolved, fill the flask with distilled water to the 100 cm³ mark.
Step 4
Predict the student's result for the viscosity, in units, of a 10.0% gelatin solution.
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Answer
Based on the trend shown in the table, the predicted result for the viscosity of a 10.0% gelatin solution can be inferred to be approximately 11 units.
Step 5
Explain why the rate of hydrolysis is reduced.
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Answer
The rate of hydrolysis is reduced when pineapple is cooked because the heat denatures the bromelain enzymes, altering their shape and active sites. This denaturation prevents the enzymes from effectively catalyzing the hydrolysis of gelatin.
Step 6
Calculate the mass, in g, of this pineapple that would be needed to provide 500 mg of bromelain.
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Answer
To calculate the mass of pineapple needed to provide 500 mg of bromelain, we can use the average bromelain content of 21 mg (between 13 mg and 29 mg) per gram of pineapple. Thus:
extMassofpineappleneeded=21 mg/g500 mg≈23.81extg
Therefore, approximately 23.81 grams of pineapple would be required.
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