Cambridge IGCSE · thinka-original Practice Paper

2024 Cambridge IGCSE Food and Nutrition (0648) Practice Paper with Answers

Thinka Jun 2024 (V2) Cambridge IGCSE-Style Mock — Food and Nutrition (0648)

200 marks360 mins2024
An original Thinka practice paper modelled on the structure and difficulty of the Jun 2024 (V2) Cambridge IGCSE Food and Nutrition (0648) paper. Not affiliated with or reproduced from Cambridge.

Section A

Answer all questions. You are advised to spend no longer than 45 minutes on this section.
5 Question · 40 marks
Question 1 · short_answer
8 marks
(a) State two functions of vitamin B2 (riboflavin) in the human body. [2]

(b) Name four good food sources of riboflavin. [4]

(c) State two symptoms of riboflavin deficiency. [2]
Show answer & marking scheme

Worked solution

(a) Functions of riboflavin include:
1. Assists in the release of energy from carbohydrates, proteins, and fats.
2. Maintains healthy skin, eyes, and the nervous system.
3. Essential for cell respiration and growth.

(b) Good food sources of riboflavin include:
1. Milk and dairy products (e.g., cheese, yogurt)
2. Eggs
3. Organ meats (e.g., liver, kidney)
4. Yeast extract (e.g., Marmite)
5. Green leafy vegetables (e.g., spinach)
6. Fortified breakfast cereals

(c) Symptoms of riboflavin deficiency (ariboflavinosis) include:
1. Cheilosis (painful cracks/fissures at the corners of the mouth)
2. Angular stomatitis (inflammation of the corners of the mouth)
3. Glossitis (sore, red, swollen tongue)
4. Dermatitis (itchy, scaly skin lesions)
5. Sore, red, itchy, or watery eyes

Marking scheme

(a) [Max 2 marks]
1 mark for each correct function of riboflavin.
- Energy release from nutrients [1]
- Promotes healthy skin/eyes/nervous system [1]
- Role in cellular respiration/growth [1]

(b) [Max 4 marks]
1 mark for each correct food source.
Acceptable answers include: milk, cheese, yogurt, eggs, liver, kidney, yeast extract, green leafy vegetables, fortified cereals.

(c) [Max 2 marks]
1 mark for each correct deficiency symptom.
- Cracks at the corners of the mouth / cheilosis [1]
- Sore/magenta tongue / glossitis [1]
- Dry, scaly skin / dermatitis [1]
- Itchy, watery, or red eyes [1]
Question 2 · short_answer
8 marks
(a) Define the term 'dietary fibre' (non-starch polysaccharide / NSP) and state its primary chemical component. [2]

(b) State three physiological benefits of including adequate dietary fibre in the diet. [3]

(c) Name three high-fibre food ingredients that can be easily incorporated into home-baked bread. [3]
Show answer & marking scheme

Worked solution

(a) Dietary fibre (NSP) is the indigestible part of plant-based foods that cannot be broken down by human digestive enzymes in the small intestine [1 mark]. Its primary chemical component is cellulose [1 mark].

(b) Physiological benefits of dietary fibre:
1. Absorbs water, swelling to bulk feces and soften waste, making it easier to pass.
2. Stimulates peristalsis (muscle contractions of the gut), which prevents constipation.
3. Lowers the risk of bowel disorders such as diverticular disease, haemorrhoids, and bowel cancer.
4. Slows down the absorption of glucose, helping to control blood sugar levels.
5. Promotes satiety (feeling of fullness), helping in the prevention of obesity.
6. Assists in lowering blood cholesterol levels.

(c) High-fibre ingredients for bread include:
1. Wholemeal or whole-wheat flour
2. Bran (wheat bran or oat bran)
3. Rolled oats or oatmeal
4. Seeds (e.g., linseed/flaxseed, chia, sunflower, pumpkin, sesame seeds)
5. Cracked wheat or bulgur wheat
6. Dried fruits (e.g., raisins, sultanas)

Marking scheme

(a) [Max 2 marks]
- Definition: Indigestible carbohydrate / plant material not broken down by digestive enzymes [1 mark]
- Primary chemical component: Cellulose [1 mark]

(b) [Max 3 marks]
1 mark for each physiological benefit.
- Absorbs water / bulks/softens feces [1]
- Stimulates peristalsis / prevents constipation [1]
- Reduces risk of bowel cancer / diverticular disease [1]
- Regulates blood sugar / slows glucose absorption [1]
- Increases satiety / aids weight control [1]
- Helps lower blood cholesterol [1]

(c) [Max 3 marks]
1 mark for each valid food ingredient.
Acceptable answers include: Wholemeal flour, bran, oats, seeds (or named seed), nuts, dried fruit.
Question 3 · short_answer
8 marks
(a) State four safety rules that must be followed when using and caring for kitchen knives to prevent cuts. [4]

(b) Explain four safety precautions to take in the kitchen to prevent accidental burns or scalds during cooking. [4]
Show answer & marking scheme

Worked solution

(a) Safety rules for knives:
1. Keep knives sharp; dull knives are more prone to slipping and causing injuries.
2. Use the correct knife for the specific task (e.g., a paring knife for peeling fruit).
3. Always cut on a secure, flat chopping board, never in your hand.
4. Cut away from your body and keep fingers curled back (claw grip).
5. Wash knives separately; never leave them submerged in soapy water where they cannot be seen.
6. Carry knives pointing downwards, close to the side of your leg.
7. Store knives in a knife block or magnetic strip rather than loose in a drawer.

(b) Safety precautions to prevent burns and scalds:
1. Turn saucepan handles inward, away from the front of the cooker hob, to prevent them from being knocked over.
2. Always use dry oven gloves or cloths; damp cloths conduct heat rapidly and generate hot steam.
3. Tilt saucepan lids away from your face when opening them to allow steam to escape safely.
4. Do not overfill pots with hot liquids or deep fryers with oil to avoid boil-overs.
5. Keep children and pets away from active cooking zones.
6. Avoid wearing loose clothing, dangling sleeves, or long jewelry that could catch fire or snag on pot handles.

Marking scheme

(a) [Max 4 marks]
1 mark for each safety rule.
- Keep knives sharp [1]
- Use correct knife for the task [1]
- Use stable chopping board [1]
- Cut away from body/fingers (claw grip) [1]
- Wash separately / do not leave in soapy water [1]
- Carry pointing down beside leg [1]
- Store in block/rack, not loose in drawer [1]

(b) [Max 4 marks]
1 mark for each explained safety precaution.
- Turn pan handles inwards / away from edge [1]
- Use dry oven gloves (explain: damp cloths cause steam burns) [1]
- Open pot lids away from you (explain: directs steam away) [1]
- Do not overfill pans with hot oil/liquid [1]
- Avoid loose clothing around heat [1]
- Ensure hobs are turned off immediately after use [1]
Question 4 · short_answer
8 marks
(a) Explain how high sugar content acts as a preservative in home-made jam. [2]

(b) State two reasons why pectin is a necessary component in jam making, and name two fruits high in pectin. [4]

(c) Name two other preservation methods that rely on the removal of water to prevent food spoilage. [2]
Show answer & marking scheme

Worked solution

(a) Preservation mechanism of high sugar content:
High concentrations of sugar create a hypertonic environment, drawing water out of any micro-organism cells present by the process of osmosis [1]. This dehydrates the microbial cells, making it impossible for bacteria, yeasts, or moulds to grow, survive, or reproduce [1].

(b) Importance of pectin and sources:
- Reasons why pectin is necessary: Pectin is a soluble structural polysaccharide that acts as a gelling agent [1]. In the presence of sugar and acid, it forms a secure network/gel, setting the jam and giving it its characteristic thick, spreadable consistency [1].
- Fruits high in pectin: Plums, cooking apples, lemons, oranges, blackcurrants, gooseberries, damsons [any two, 1 mark each].

(c) Water removal preservation methods:
1. Sun drying / dehydration / oven drying
2. Freeze drying / spray drying
3. Salting (dry salting/curing)
4. Smoking

Marking scheme

(a) [Max 2 marks]
- Mentions hypertonic solution / draws water out of microbial cells by osmosis [1 mark]
- Micro-organisms are dehydrated/cannot survive/multiply without available water [1 mark]

(b) [Max 4 marks]
- Reasons why pectin is needed (max 2 marks): Acts as a gelling agent [1]; sets the jam / yields correct consistency [1].
- Fruits high in pectin (max 2 marks): 1 mark for each correct fruit (e.g., apple, lemon, lime, plum, gooseberry, blackcurrant).

(c) [Max 2 marks]
1 mark for each valid method.
Acceptable answers include: Drying/dehydration, salting/dry curing, smoking, freeze-drying.
Question 5 · short_answer
8 marks
(a) Identify the gas produced by yeast during fermentation that causes bread dough to rise. [1]

(b) State the four conditions required for yeast to grow and produce gas in bread-making. [4]

(c) Explain what happens to yeast cells when bread dough is baked in a hot oven, and state the temperature range at which this occurs. [3]
Show answer & marking scheme

Worked solution

(a) Carbon dioxide / \(CO_2\).

(b) Conditions required for yeast growth:
1. Warmth (ideal temperature is around \(25^\circ C - 35^\circ C\)).
2. Moisture / water / liquid (to activate the yeast cells).
3. Food / sugar / fermentable carbohydrate (such as glucose, for the yeast to feed on).
4. Time (for fermentation and gas production to occur).

(c) When bread dough is baked in a hot oven:
- The intense heat kills the yeast cells and denatures the enzymes responsible for fermentation [1].
- Consequently, fermentation ceases and gas production stops, fixing the expanded shape of the bread [1].
- This yeast destruction happens when the internal temperature of the dough rises to between \(55^\circ C\) and \(60^\circ C\) (accept any temperature within the range \(50^\circ C - 65^\circ C\)) [1].

Marking scheme

(a) [Max 1 mark]
- Carbon dioxide / \(CO_2\) [1]

(b) [Max 4 marks]
1 mark for each required condition.
- Warmth / correct temperature [1]
- Moisture / liquid [1]
- Food / sugar [1]
- Time [1]

(c) [Max 3 marks]
- Yeast is killed / enzymes are denatured [1]
- Fermentation / gas production stops [1]
- Occurs at \(55^\circ C\) to \(60^\circ C\) (accept any specific temperature or range from \(50^\circ C\) to \(65^\circ C\)) [1]

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Section B

Answer all questions.
6 Question · 45 marks
Question 1 · Structured Science & Safety Applications
7.5 marks
Cleaning food preparation areas thoroughly is essential to prevent food poisoning, but kitchen staff must follow strict safety procedures when handling chemical sanitizers and cleaning motorized equipment.

(a) State three safety precautions to follow before cleaning an electric commercial food slicer. [3]

(b) Explain why chemical sanitizers must be used at the correct concentration and contact time. [3]

(c) State three symptoms of chemical contamination if sanitizers accidentally transfer to food. [1.5]
Show answer & marking scheme

Worked solution

(a) Before cleaning an electric commercial food slicer, the following safety precautions must be taken:
1. Turn off the slicer and unplug it from the electrical mains socket to prevent accidental activation.
2. Wear heavy-duty, cut-resistant gloves to protect hands from the sharp blade.
3. Turn the thickness control dial to zero (fully closed position) so the blade edge is not exposed.

(b) Chemical sanitizers require specific conditions to work effectively and safely:
- **Concentration:** If the mixture is too weak, it will not kill pathogenic microorganisms. If it is too strong, it can leave toxic chemical residues on food-contact surfaces, causing chemical food poisoning.
- **Contact Time:** Sanitizers do not kill bacteria instantly; they require a specific contact time to successfully disrupt and destroy microbial cell membranes.

(c) Symptoms of consuming food contaminated with chemical sanitizers include:
1. Nausea and vomiting.
2. Burning sensations in the mouth, throat, or stomach.
3. Abdominal pain or stomach cramps.

Marking scheme

Part (a) [Total: 3 marks]
Award 1 mark for each valid safety precaution listed (up to 3):
- Switch off and unplug the appliance from the mains. [1 mark]
- Wear protective / cut-resistant safety gloves. [1 mark]
- Set the blade indicator / thickness dial to zero / closed position. [1 mark]
- Do not spray water or cleaning chemicals directly into the motor housing. [1 mark]

Part (b) [Total: 3 marks]
Award 1.5 marks for explanation of concentration:
- Too weak does not kill pathogens [0.75 marks] and too strong leaves toxic chemical residues / causes chemical contamination [0.75 marks].
Award 1.5 marks for explanation of contact time:
- The chemical needs sufficient exposure time to react with / penetrate and destroy the cell walls of microorganisms [1.5 marks].

Part (c) [Total: 1.5 marks]
Award 0.5 marks for each valid symptom of chemical contamination (up to 3):
- Vomiting / nausea [0.5 marks]
- Burning in mouth / throat / esophagus [0.5 marks]
- Abdominal pain / stomach cramps [0.5 marks]
- Dizziness / headache [0.5 marks]
Question 2 · Structured Science & Safety Applications
7.5 marks
A student is preparing a traditional white sauce (béchamel) and deep-fried potato croquettes.

(a) Describe the scientific process of starch gelatinisation when making a white sauce. [4]

(b) State three safety rules that must be followed when deep-frying the potato croquettes to prevent a kitchen fire. [3]

(c) State the type of fire extinguisher that should be used to put out a cooking oil fire. [0.5]
Show answer & marking scheme

Worked solution

(a) Starch gelatinisation occurs in the following stages:
1. Starch granules are suspended in liquid (milk) and heated.
2. At around 60°C, the starch granules absorb the liquid and begin to swell.
3. As the temperature rises, the granules continue to absorb liquid and swell to many times their original size, making the mixture viscous/thick.
4. Around 85°C, the swollen starch granules burst, releasing amylose and amylopectin molecules into the surrounding liquid, trapping the liquid and forming a thick gel upon boiling and cooling.

(b) Safety rules for deep-fat frying:
1. Do not fill the deep-frying pan more than half-full with oil to prevent boiling over.
2. Ensure food (potato croquettes) is dried thoroughly with a paper towel before frying to prevent water droplets from causing hot oil to spit.
3. Never leave the deep-fat fryer or pan unattended while the heat is on.

(c) A Class F (or Class K in some regions) wet chemical fire extinguisher, or a fire blanket, must be used to extinguish cooking oil fires.

Marking scheme

Part (a) [Total: 4 marks]
Award 1 mark for each step in the scientific process of gelatinisation (up to 4):
- Starch granules are suspended in liquid and heated. [1 mark]
- At 60°C, starch granules absorb liquid and swell. [1 mark]
- The mixture thickens as granules swell and restrict liquid movement. [1 mark]
- At 85°C, the starch granules burst. [1 mark]
- Amylose/amylopectin are released, trapping the liquid to form a thick gel upon boiling. [1 mark]

Part (b) [Total: 3 marks]
Award 1 mark for each valid safety rule to prevent fire (up to 3):
- Do not overfill the pan with oil (maximum half-full). [1 mark]
- Dry food thoroughly before putting it into the oil. [1 mark]
- Never leave the pan/fryer unattended. [1 mark]
- Heat the oil gradually and do not let it reach its smoke point. [1 mark]
- Use a thermometer to control temperature. [1 mark]

Part (c) [Total: 0.5 marks]
Award 0.5 marks for identifying the correct fire fighting equipment:
- Wet chemical / Class F / Class K fire extinguisher or fire blanket. [0.5 marks]
- Reject: Water / carbon dioxide / foam extinguishers.
Question 3 · Structured Science & Safety Applications
7.5 marks
Raw poultry carries a high risk of foodborne pathogens and requires careful handling and cooking.

(a) Explain the term cross-contamination and describe how it can be prevented during the preparation of chicken breasts. [3]

(b) Explain how heat causes the denaturation and coagulation of protein in chicken muscle fibers during cooking. [3]

(c) State the minimum internal temperature cooked poultry must reach to ensure all pathogenic bacteria are destroyed, and name the tool used to verify this temperature. [1.5]
Show answer & marking scheme

Worked solution

(a) Cross-contamination is the transfer of harmful bacteria or microorganisms from a contaminated source (like raw poultry) to ready-to-eat food or clean kitchen utensils. It can be prevented by:
- Using a designated, color-coded chopping board (typically red) exclusively for raw poultry.
- Washing hands thoroughly with warm water and antibacterial soap immediately after handling raw chicken.
- Storing raw poultry on the bottom shelf of the refrigerator so its juices cannot drip onto other foods.

(b) During cooking, heat affects the protein in chicken muscle fibers through:
- **Denaturation:** Heat disrupts the chemical bonds that maintain the protein's unique, folded three-dimensional shape. This causes the protein chains to unfold and straighten.
- **Coagulation:** The unfolded protein chains bump into each other and form new, permanent bonds, creating a dense, solid network that traps water. This changes the texture from soft and translucent to firm and opaque.

(c) Cooked poultry must reach a minimum internal temperature of 75°C (167°F) to be safe. This temperature must be verified using a digital food probe thermometer inserted into the thickest part of the meat.

Marking scheme

Part (a) [Total: 3 marks]
Award 1 mark for the definition of cross-contamination:
- Transfer of harmful bacteria/pathogens from a raw/contaminated food to cooked/ready-to-eat food. [1 mark]
Award 1 mark each for any two valid prevention methods (up to 2):
- Use a designated red / raw meat cutting board. [1 mark]
- Wash hands with warm soapy water immediately after contact with raw meat. [1 mark]
- Store raw chicken on the lowest shelf of the fridge. [1 mark]
- Clean and sanitize all knives and surfaces after preparation. [1 mark]

Part (b) [Total: 3 marks]
Award 1.5 marks for explanation of denaturation:
- Heat breaks chemical bonds [0.75 marks] and causes protein chains to unfold / lose their shape [0.75 marks].
Award 1.5 marks for explanation of coagulation:
- Unfolded proteins form new bonds / clump together [0.75 marks] to create a firm, solid network that traps water [0.75 marks].

Part (c) [Total: 1.5 marks]
Award 1 mark for the correct temperature:
- 75°C / 74°C / 165°F. [1 mark]
Award 0.5 marks for the correct tool:
- Food probe thermometer / meat thermometer. [0.5 marks]
Question 4 · Structured Science & Safety Applications
7.5 marks
When preparing fresh apples for a fruit salad, they quickly turn brown, which affects their appearance and appeal.

(a) Explain the chemical reaction that causes freshly cut apples to turn brown. [3]

(b) Suggest three different culinary methods to prevent this browning from occurring, giving a scientific explanation for each method. [3]

(c) State three safety guidelines to follow when using a chef's knife to slice apples. [1.5]
Show answer & marking scheme

Worked solution

(a) The chemical reaction is called enzymic browning. When apple cells are cut, the cell walls rupture and expose an enzyme called polyphenol oxidase (or phenolase) and phenolic compounds to oxygen in the air. The enzyme acts as a catalyst, causing the oxygen to react with the phenols (oxidation), producing brown-colored pigments called melanins.

(b) Methods to prevent enzymic browning and their scientific explanations:
1. **Acidulation (e.g., dipping in lemon juice):** The highly acidic environment (low pH) denatures and deactivates the polyphenol oxidase enzyme, stopping the reaction.
2. **Blanching (immersing in boiling water briefly):** High heat denatures and permanently deactivates the protein-based enzyme.
3. **Submersion in water:** Placing the cut apples under water acts as a physical barrier that prevents oxygen from reaching the tissue, preventing oxidation.

(c) Knife safety guidelines when slicing apples:
1. Use the 'claw grip' to hold the apple, keeping fingertips curled inward and away from the blade.
2. Always cut on a secure, stable, non-slip chopping board.
3. Keep the knife sharp, as a dull knife requires more force and is more likely to slip and cause injury.

Marking scheme

Part (a) [Total: 3 marks]
Award 1 mark for each key point of enzymic browning (up to 3):
- Cell rupture exposes enzyme (polyphenol oxidase / phenolase) and phenolic substrates. [1 mark]
- Oxygen in the air reacts with the phenolic compounds (oxidation). [1 mark]
- This reaction is catalyzed by the enzyme and produces brown pigments / melanin. [1 mark]

Part (b) [Total: 3 marks]
Award 1 mark for each method with its corresponding scientific explanation (up to 3):
- Acidulation / dipping in citrus juice: the low pH denatures / inactivates the enzyme. [1 mark]
- Blanching / heating: thermal energy denatures the enzyme. [1 mark]
- Submerging in water: blocks oxygen from entering the cut cells / prevents contact with air. [1 mark]
- Coating with sugar syrup: acts as a barrier to exclude oxygen. [1 mark]
- Adding an antioxidant (ascorbic acid): reacts with oxygen first, preventing oxidation of phenols. [1 mark]

Part (c) [Total: 1.5 marks]
Award 0.5 marks for each valid knife safety guideline (up to 3):
- Keep fingers curled in a claw grip. [0.5 marks]
- Cut on a flat, stable, non-slip chopping board. [0.5 marks]
- Ensure the knife is sharp. [0.5 marks]
- Cut away from the body / fingers. [0.5 marks]
- Do not leave knives in a sink full of soapy water. [0.5 marks]
Question 5 · Structured Science & Safety Applications
7.5 marks
Baking powder and steam are two different types of raising agents used in flour mixtures.

(a) Explain how baking powder works as a chemical raising agent when liquid and heat are applied during baking. [3]

(b) Explain how steam acts as a physical raising agent in a mixture such as choux pastry, including the conditions required for it to be effective. [3]

(c) State three safety precautions to observe when opening and placing items into a hot domestic oven. [1.5]
Show answer & marking scheme

Worked solution

(a) Baking powder is a chemical raising agent containing an acid (e.g., cream of tartar), an alkali (sodium bicarbonate), and starch.
- When liquid is added to the mixture, the acid and alkali dissolve and react with each other.
- This reaction releases carbon dioxide (\(CO_2\)) gas.
- When heat is applied during baking, the gas expands, and additional chemical reactions take place to release more gas, causing the mixture to rise.

(b) Steam acts as a physical raising agent through the expansion of water vapor:
- Choux pastry contains a very high proportion of liquid. When placed in the oven, this moisture turns into steam.
- The steam expands to 1600 times the volume of the water, forcing the raw batter outwards and upwards, creating a large hollow center.
- For this to work, a very high oven temperature (typically above 200°C) is required to vaporize the water quickly before the egg protein coagulates and sets the pastry's structure.

(c) Safety precautions when using a hot domestic oven:
1. Always wear dry, insulated oven gloves (wet gloves conduct heat and can cause steam burns).
2. Stand to one side of the oven when opening the door to let the hot air and steam escape safely.
3. Pull the oven rack out slightly before placing baking trays onto it, instead of reaching deep inside the hot oven chamber.

Marking scheme

Part (a) [Total: 3 marks]
Award 1 mark for each key concept (up to 3):
- Baking powder contains both an acid and an alkali (sodium bicarbonate). [1 mark]
- Moisture dissolves the chemicals, allowing them to react and produce carbon dioxide (CO2) gas. [1 mark]
- Heat causes the gas bubbles to expand, pushing up the mixture, and accelerates gas production. [1 mark]

Part (b) [Total: 3 marks]
Award 1 mark for each key concept (up to 3):
- The mixture must contain a high proportion of liquid / moisture. [1 mark]
- High heat converts this moisture into steam, which expands and forces the dough / pastry to rise. [1 mark]
- Requires a very hot oven (above 200°C / gas mark 6-7) to quickly produce steam before the protein / starch sets the structure. [1 mark]

Part (c) [Total: 1.5 marks]
Award 0.5 marks for each valid safety precaution (up to 3):
- Use thick, dry oven gloves / mitts. [0.5 marks]
- Stand to the side of the oven door when opening. [0.5 marks]
- Pull out oven racks slightly before loading/unloading. [0.5 marks]
- Ensure no children or pets are near the hot oven door. [0.5 marks]
- Avoid touching the hot heating elements or oven interior. [0.5 marks]
Question 6 · Structured Science & Safety Applications
7.5 marks
Chilling and freezing are widely used methods to extend the shelf life of highly perishable foods.

(a) Contrast the scientific effect of chilling (at 1°C to 5°C) with freezing (at -18°C or below) on the growth of food-spoilage microorganisms. [3]

(b) Explain why frozen foods, particularly raw meats, must be defrosted thoroughly before cooking, and describe the safest method to do so. [3]

(c) State three signs of 'freezer burn' on food and explain how it affects the quality of the food. [1.5]
Show answer & marking scheme

Worked solution

(a) Contrast between chilling and freezing on microorganisms:
- **Chilling (1°C to 5°C):** This temperature range slows down the rate of multiplication and metabolism of most food-spoilage and pathogenic bacteria, but does not stop it completely. Microorganisms continue to grow, but at a much slower rate.
- **Freezing (-18°C or below):** This temperature completely stops the growth and multiplication of all microorganisms. Water in the food is converted into ice crystals, which deprives bacteria of the liquid moisture they need to live and reproduce. However, freezing does not kill the microorganisms; they simply become dormant.

(b) Defrosting science and procedure:
- **Why:** If food is not fully defrosted, the center remains frozen. During cooking, the heat energy is used up thawing the icy core rather than cooking it, meaning the internal temperature of the food may not reach the required 75°C. This allows pathogenic bacteria in the center to survive and cause food poisoning.
- **Safest Method:** Defrost the food slowly in the refrigerator on the bottom shelf. The cool refrigerator temperature (1°C to 5°C) prevents the outer layers of the food from entering the danger zone (5°C to 63°C) while the center gradually thaws.

(c) Freezer burn:
- **Signs:** Dry, greyish-brown patches on meat, a shriveled or dehydrated surface texture, and the presence of heavy ice crystals on the packaging or food.
- **Effect on Quality:** Freezer burn causes moisture loss through sublimation, leaving the food tough, dry, stringy, and lacking in its natural flavor when cooked.

Marking scheme

Part (a) [Total: 3 marks]
Award 1.5 marks for explanation of chilling:
- Temperatures of 1°C to 5°C slow down / retard bacterial growth / chemical activity [1 mark] but do not stop it completely / spoilage eventually occurs [0.5 marks].
Award 1.5 marks for explanation of freezing:
- Temperatures of -18°C or below halt / stop microbial growth completely [1 mark] because liquid water is unavailable / turned to ice [0.5 marks].

Part (b) [Total: 3 marks]
Award 1.5 marks for the explanation of the risk of incomplete defrosting:
- Frozen cores take longer to heat; heat won't penetrate to the center [0.75 marks] meaning the core won't reach the safety temperature of 75°C to destroy pathogens / bacteria will survive [0.75 marks].
Award 1.5 marks for description of the safest defrosting method:
- Thaw inside the refrigerator / chiller [0.75 marks] on the bottom shelf to keep the surface out of the 'danger zone' (5°C to 63°C) / to prevent cross-contamination from drips [0.75 marks].

Part (c) [Total: 1.5 marks]
Award 0.5 marks for each valid sign/effect of freezer burn (up to 3):
- Greyish / brownish-white patches on the surface of the food. [0.5 marks]
- Shriveled / dehydrated / dry texture. [0.5 marks]
- Excess ice crystals inside the package. [0.5 marks]
- Loss of flavor / rancidity of fats. [0.5 marks]
- Food becomes tough / fibrous when cooked. [0.5 marks]

Section C

Answer either Question 12 or Question 13.
1 Question · 15 marks
Question 1 · essay
15 marks
Dietary fibre (NSP) is a crucial component of a healthy diet.

Discuss the health benefits of dietary fibre (NSP) and explain how consumers can increase their intake of fibre when preparing and cooking family meals.
Show answer & marking scheme

Worked solution

Candidates should cover two main areas in their essay:
1. The physiological and health benefits of dietary fibre (NSP) in the body.
2. Practical culinary methods to incorporate more high-fibre ingredients during meal preparation and cooking.

Health Benefits of Dietary Fibre (NSP):
- **Water Absorption & Bulk:** NSP absorbs moisture in the intestines, swelling to provide soft bulk to the faeces.
- **Stimulation of Peristalsis:** The bulk stretches the gut wall, stimulating muscular contractions (peristalsis) to quickly clear waste.
- **Prevents Constipation:** Keeps stools soft and easy to pass, avoiding straining.
- **Reduces Bowel Disorders:** Lower transit time reduces the risk of diverticular disease, haemorrhoids (piles), and colorectal cancer.
- **Weight Management / Satiety:** High-fibre foods expand in the stomach, promoting a feeling of fullness and preventing overeating / obesity.
- **Blood Sugar Control:** Soluble fibre slows down carbohydrate digestion, preventing rapid glucose spikes (beneficial for type 2 diabetes management).
- **Lowering Cholesterol:** Soluble fibre binds to cholesterol-rich bile acids, helping to lower blood cholesterol levels and reduce Coronary Heart Disease (CHD) risk.
- **Healthy Gut Microbiome:** Acts as a prebiotic, feeding beneficial gut flora.

Practical Ways to Increase Fibre Intake in Family Meals:
- **Whole Grain Substitutions:** Use wholemeal bread, brown rice, and wholemeal pasta instead of white, highly refined versions.
- **Retain Edible Skins:** Do not peel fruits (e.g., apples, pears) and vegetables (e.g., potatoes, carrots, cucumbers) before cooking or serving.
- **Incorporate Pulses:** Add lentils, chickpeas, and beans to soups, stews, casseroles, or minced meat mixtures to stretch the meal and add fibre.
- **Flour Modification:** Replace white flour with wholemeal flour (entirely or in a 50/50 mix) when preparing pastries, crumbles, sauces, or bread.
- **Add Oats:** Use oats to thicken soups/sauces, as a topping for fruit crumbles, or in home-baked biscuits.
- **Incorporate Seeds and Nuts:** Sprinkle pumpkin, flax, or sesame seeds on salads, stir-fries, or mix them into bread and cake mixtures.
- **Focus on High-Fibre Vegetables:** Choose high-fibre side dishes such as peas, broccoli, and sweetcorn.
- **Dried Fruit Additions:** Include dried apricots, raisins, or figs in desserts, breakfast cereals, or savoury grain dishes.

Marking scheme

Award up to 15 marks in total, structured as follows:

**Positive health benefits of dietary fibre (NSP) [Max 8 marks]:**
- Absorbs water / swells [1]
- Adds bulk to stools [1]
- Stimulates peristalsis / muscular contractions [1]
- Prevents constipation [1]
- Prevents haemorrhoids / piles [1]
- Prevents diverticular disease [1]
- Reduces risk of colon / bowel cancer [1]
- Promotes feeling of fullness / satiety / weight management [1]
- Slows glucose absorption / regulates blood sugar levels / type 2 diabetes management [1]
- Lowers blood cholesterol levels / reduces risk of CHD [1]
- Prebiotic effect / feeds gut bacteria [1]

**Practical preparation and cooking methods [Max 8 marks]:**
- Use whole grain cereals (e.g. brown rice / wholemeal pasta / wholemeal bread) [1]
- Do not peel fruits / vegetables / leave skins on potatoes, carrots, apples [1]
- Add pulses (lentils, beans, chickpeas) to stews / casseroles / mince dishes [1]
- Substitute white flour with wholemeal flour in baking (cakes, pastry, bread) [1]
- Add oats to crumbles / cookies / use oats to thicken soups [1]
- Add seeds / nuts to salads, bakes, or stir-fries [1]
- Choose high-fibre vegetables (e.g., broccoli, Brussels sprouts, peas) as sides [1]
- Add dried fruits (e.g., sultanas, prunes) to desserts, cereals, or baked goods [1]
- Serve raw vegetable crudités instead of cooked/processed snacks [1]

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