HSC central resources Senior science Preservatives …...HSC central resources Senior science...

HSC central resources Senior science Preservatives and additives

1 | P a g e

2001 Question 28 — Preservatives and Additives (25 marks)

(a) (i) Identify ONE process that can be used to physically preserve food. 1

(ii) Describe how this process preserves food. 2

(b) The diagrams show the effect of temperature on the bacteria that cause food-

poisoning and the food-poisoning chain.

(i) Foods are sometimes kept warm at approximately 55°C . What is ONE 1 problem associated with this practice?

(ii) Explain how you could break the food-poisoning chain to prevent food- 3

poisoning. (c) Identify and explain the important steps leading to the discovery of the 5

antibiotic, penicillin.

(d) (i) Outline an investigation in which you determined the pH of a range of 3 consumer products.


2 | P a g e

(ii) Explain how pH might influence the activity of microorganisms during 3

the manufacture of these products.

(e) The National Food Authority uses codes as alternatives to the names of 7 preservatives and additives on labels.

Assess the need for labelling of additives and preservatives.


3 | P a g e

2002 Question 29 — Preservatives and Additives (25 marks) (a) (i) Identify ONE substance that can be used as a natural food dye. 1

(ii) Describe the effects of adding food dyes to food. 3

(b) The Australia New Zealand Food Authority (ANZFA) has published the Food

Standards Code.

In this Code, the term ‘preservatives’ includes:

• benzoic acid and its salts

• dimethyl dicarbonate

• methylparaben

• sulfur dioxide

• nisin

• sorbic acid and its salts

• propionic acid and its salts.

(i) Identify a bacteriocin from the list above. 1

(ii) Assess the need for control and labelling of additives and preservatives in 5 food and drink products.

(c) Discuss the historical development of our scientific understandings of the causes 7

of food spoilage. In your answer, you should relate these understandings to improved methods of food preservation and the impact of these methods on society.

(d) A student carried out an investigation to determine the minimum temperature to which soup should be heated to ensure that all micro-organisms are destroyed. In her investigation she heated soups to different temperatures, extracted samples of the soups and grew the samples in 10 cm agar square dishes.

After three days she estimated the percentage cover of micro-organisms on the agar by using a grid. Her results are shown in the table.

Temperature to which the soup was heated (°C)

Percentage of the agar plate covered by micro-organisms

30 20 40 40


4 | P a g e

50 60 60 80 70 0 80 0

(i) Using the information in the table, determine the minimum safe 1 temperature to which soup should be heated to destroy the micro-organisms.

(ii) The diagram shows colonies of micro-organisms that were grown on 3

agar in a 10 cm square dish from a sample of her soup.

Determine the percentage of the agar covered in micro-organisms and the temperature to which the soup was heated. Show your working.

(iii) How should the student minimise any potential risks involved in carrying 4

out this investigation?


5 | P a g e

2003 Question 29 — Preservatives and Additives (25 marks) (a) (i) Identify ONE bacterial microbe that causes spoilage in food. 1

(ii) Describe how the use of ultra-high temperature (UHT) as a preservative 3

measure has improved the quality of food available for society. (b) (i) Identify ONE way in which bacteriocins can be used to preserve food. 1

(ii) The diagrams show labels found on two food containers. 5

DANGER This food may contain substances that can cause allergic reactions

in some people.

Ingredients: Corn and/or Rice, Vegetable Oil, Skim Milk Powder, Whole Milk

Powder, Cheese Powder (3.0%), Salt, Whey Powder, Yeast and/or

Extracts, Hydrolysed Vegetable Protein, Flavour Enhancers (621, 631, 627), Food Acids (262, 270, 330, 331), Mineral Salt (339),

Flavours, Anti-Caking Agent (504), Onion Powder, Herbs,

Spices and/or Extracts, Antioxidants (304, 306).

No Preservatives. No Artificial Colours.

No Artificial Flavours.

Food Label 1 Food Label 2

Discuss the usefulness of these labels, and explain how they can be improved.

(c) Discuss the addition of substances to improve the appearance and shelf-life of 7

cosmetic products. (d) (i) Distinguish between the roles of preservatives and additives used in 2

foods.


6 | P a g e

(ii) In your study of Preservatives and Additives, you carried out a first-hand 3 investigation to compare the solubilities of preservatives such as nitrates, nitrites and sulfites. Outline your investigation, including the procedure used and a summary of your results.

(iii) How does the solubility of the compounds you investigated relate to their 3

role as preservatives in cured meats?


7 | P a g e



8 | P a g e

(c) The Australian Food Standards codes are numbers listed on the labels on food 7 products. One ingredient of a generic brand of cooking salt is the anticaking agent 554 (sodium aluminosilicate) while another brand of cooking salt contains 535 (sodium ferrocyanide).

Discuss the use of the Australian Food Standards codes on labels as alternatives to the names of preservatives and additives.

(d) (i) How does salt act as a preservative in food? 1


9 | P a g e

(ii) A group of students, Alicia, Daniel, Patrick and Alex, investigated the 3 flow rate of salt and the effect of adding glucose to the salt.

They prepared three samples by mixing different masses of salt and glucose in Petri dishes and allowed them to stand for 48 hours.


10 | P a g e


(a) (i) During your study of this option you have undertaken a range of 2 practical experiences that have involved collecting data.

Identify TWO differences between first-hand and secondary-source investigations.

(ii) Danni took some sultanas and placed them in a beaker of water. After 2 one hour, Danni noticed that the sultanas were swollen.

Explain why the sultanas became swollen in terms of your understanding of osmosis.

(b) Mieke often makes ‘pickled cucumber’ for an Indonesian dish. She slices cucumbers very thinly and then places them in a clean bowl containing castor sugar dissolved in vinegar. The bowl of cucumber is then placed in the refrigerator, where it remains fresh for several days.

(i) Justify TWO methods Mieke uses to preserve the cucumber. 3 (ii) Compare TWO preservation techniques used by different cultures. 3

(c) Many Australians are concerned with the large number of preservatives and

additives in food.

Assess the advantages and disadvantages to society of using chemical additives 7 and preservatives in our food.


11 | P a g e

(d) Marmalades are jams containing citrus fruits and usually have lemon or orange

peel suspended in the mixture. Citrus fruits are rich in pectin, so that the jam will set.

Awaiting Copyright Clearance

(i) Name ONE natural preservative in the above recipe, and describe its 2 function.

(ii) Justify the need for hot, sterilised jars and prompt sealing of home-made 3 jams.

(iii) Commercial jams are made from the same ingredients, but often have the 3 preservative potassium metabisulfite (223) added to them. Home-made jams continue to be made safely without any artificial preservatives.

Discuss the addition of metabisulfite to commercial jams.


12 | P a g e

2006 Question 28 — Preservatives and Additives (25 marks) (a) Food additives are substances that can be added to food products to achieve a

specific purpose. Sometimes they have more than one effect.

(i) Identify ONE food additive. 1

(ii) Identify a different food additive, outline its specific purpose and 3 identify another effect of this additive.

(b) This label was taken from a bottle of cream.

2007 Question 29 — Preservatives and Additives (25 marks) (a) (i) How do preservation techniques increase the shelf life of food? 1

(ii) Copy and complete the table in your writing booklet. 4


13 | P a g e

Preservation Example of Type of food method method preserved

Physical

Chemical

(b) Four new types of bacteriocins are being investigated for use in some freshly

squeezed orange juices.

To test the effectiveness of the bacteriocin, a small disc of paper which has been soaked in the bacteriocin is placed onto the surface of an agar plate. The agar plate has thousands of micro-organisms growing on it and looks cloudy.

If the bacteriocin works, the area around the disc will become clear where the micro-organisms have died.


14 | P a g e

(d) The following article was published on the internet.

Eating out a danger

Fast food restaurants and salad bars, rare 50 years ago, are today a primary source of food consumption for many Australians. In Australia, it is estimated that the number of food service outlets has grown 57 per cent with Australians spending 30 per cent of their food budget on take-away food and dining out.

Around sixty to eighty per cent of foodborne illnesses arise from take-away food or dining out.

Studies in New South Wales have shown that a history of eating out in the week before the onset of gastroenteritis was associated with a significantly increased yield of Salmonella and Campylobacter. Consequently, with the increasing trend towards take-away food and dining out, there is the likelihood of increasing numbers of people contracting foodborne illnesses.

(i) Outline how you could assess the reliability of the information presented 2 in this article.

(ii) Design a first-hand investigation to test one of the claims made in this 4

article.

(iii) Propose future directions of research relating to the incidence of 2 foodborne illnesses.


15 | P a g e


16 | P a g e

2008


17 | P a g e


(d) The following photographs show examples of food preservation methods.


18 | P a g e


19 | P a g e

2010 Question 32 — Preservatives and Additives (25 marks) (a) (i) Name a food additive that is not a preservative. 1

(ii) Contrast the roles of preservatives and other additives used in foods. 3

(b) Homemade jam was prepared from fruit and stored in screw top glass jars. After

a few months, colonies of microbes started to grow on the surface of the jam.

(i) State a problem that is evident in the scenario outlined above. 1

(ii) Propose and justify a possible strategy that could be used to solve the 3 problem you identified in part (i).

(c) (i)

(ii)

Describe the results of a first-hand investigation to demonstrate the 2 solubilities in water of nitrates, nitrites and sulfites. Relate the solubilities of nitrates, nitrites and sulfites to their roles as 3 preservatives in meats.

Answer parts (d)–(e) in a SEPARATE writing booklet.

(d) The following information refers to the work of an Australian scientist. 5

Awaiting copyright

Assess the contribution that scientific investigation of preservatives and additives makes to society using the information above to illustrate your answer.

(e) Assess the need to control both the use of additives and their labelling in food.


20 | P a g e



21 | P a g e

HSC central resources Senior science Preservatives …...HSC central resources Senior science...

Documents

Transcript of HSC central resources Senior science Preservatives …...HSC central resources Senior science...