ALS14SQ(FOOD) - Section 14.2/ Chemistry and food / 1 SKH...

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Section 14.2/ Chemistry and food / SKH Bishop Baker Secondary School AL Chemistry Section 14 Chemistry and Society (14.2 Chemistry and food) AS94A Q.7 ( II ) Chemistry and food (a) Oil and fat turn rancid and develop an ‘off’ odour after use for some time. Briefly explain how this occurs. (2 marks) (b) Both sodium nitrite and monosodium glutamate ( MSG ) are common food additives. For each of these substances, give ONE reason for its use as a food additive and ONE adverse effect from its excessive intake. Sodium nitrite Reason for use as a food additive : Adverse effect from excessive intake : Monosodium glutamate (MSG) Reason for use as a food additive : Adverse effect from excessive intake : (4 marks) AS94B Q.8 (a) Briefly explain each of the following observations and its underlying chemical principles. (i) Meat can be stored longer if placed in a freezer. AS95A Q.7 ( II ) Chemistry and food The ingredients of a brand of apple juice are listed below : water, cane sugar, concentrated apple juice, sulphur dioxide, citric acid, vitamin C, sodium citrate, flavourings, stabilizer (E466), natural colour (E160). (a) (i) Sulphur dioxide is added to prevent browning of the apple juice. Explain the action of sulphur dioxide. (ii) Suggest ONE OTHER function of sulphur dioxide in the apple juice. (iii) For humans, the acceptable daily intake (ADI) of sulphur dioxide should not exceed 0.7 mg per kg of body weight. What is the possible menace of excessive intake of sulphur dioxide ? (4 marks) (b) Sodium citrate is added to regulate the acidity of the apple juice. Explain the action of sodium citrate. (2 marks) (c) Why is cane sugar added to the apple juice ? (1 mark) 1
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Section 14.2/ Chemistry and food / AS96A Q.4 Diabetics cannot produce enough insulin (a protein) in their bodies. As a result, ingested glucose passes out in the urine without being fully utilized. The presence of glucose in the urine can be tested by the use of clinistix paper. (a) A portion of the structure of insulin is shown below : (i) Use square brackets [ ] to mark a peptide link on the above structure. (ii) Referring to the above diagram, draw the structure of ONE hydrolysis product of insulin. (2 marks) AS96A Q.7 ( II ) Chemistry and food The ingredients of a popular drink are listed below : carbonated water, sugar, caramel, phosphoric acid, caffeine and other flavourings (a) Which ingredient is most abundant in the drink ? (1 mark)
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This note was uploaded on 08/17/2011 for the course CHEM 100 taught by Professor Fleet during the Fall '08 term at Oxford University.

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ALS14SQ(FOOD) - Section 14.2/ Chemistry and food / 1 SKH...

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