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food preservation

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4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.

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Lesson Overview

Total Lessons: 4
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, Eduqas, CCEA

Learning Objectives

Prerequisites

Materials & Equipment

Lesson 1: Introduction: food preservation

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Write down everything you already know about food preservation. Then check against the key terms: key terms from food preservation. Use a mini-whiteboard or paper.

Main Content (35 minutes)

Parent/Teacher Guide:
Before lesson: Read the script below. Pre-teach key vocab: key terms from food preservation.
If stuck: Re-read the revision notes (link above), then break the content into smaller steps.
Extension: See the Stretch & Challenge ideas in Lesson 4.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: food preservation. By the end you will be able to answer exam questions on it unaided. It connects to the rest of Food Preparation and Nutrition because the ideas here recur across the spec."
Mins 5-20 - Direct Instruction: Work through the core ideas below one at a time; after each, ask your student to explain it back in their own words.
Mins 20-30 - Guided Practice: Model the worked example together, then let your student attempt the first practice question with guidance.
Mins 30-35 - Independent Practice: 2-3 practice questions from Lesson 3 below, with immediate feedback.
First Look

Start with the revision notes summary, then attempt: explain the key ideas of food preservation

Plenary (5 minutes)

Check Out

Your student states one thing they learned and one question they still have about food preservation.

Lesson 2: Core Concepts: food preservation

Duration: 50 minutes

Starter Activity (5 minutes)

Review Previous Lesson

Quick recap: write 3 key points from Lesson 1 on food preservation. Check them against the notes below.

Main Content (35 minutes)

Key Fact: Food preservation extends shelf life by preventing or slowing microbial growth (bacteria, moulds, yeasts) and enzymatic spoilage. Microorganisms need warmth, moisture, food, oxygen, and appropriate pH to grow.
Key Fact: Pasteurisation: heating food to 72°C for 15 seconds (HTST) or 63°C for 30 minutes (LTLT), then rapid cooling. Kills pathogenic bacteria but not all spoilage organisms. Used for: milk, fruit juices, eggs. Refrigerated pasteurised products have limited shelf life.
Key Fact: UHT (Ultra-High Temperature): heating to 135°C for 1-2 seconds. Kills all microorganisms including spores. UHT products (e.g. long-life milk) can be stored unrefrigerated for months in sealed containers.
Key Fact: Canning/bottling: food sealed in airtight containers and heat-treated to destroy all microorganisms. Low-acid foods (vegetables, meat) require pressure cooking at 121°C to kill Clostridium botulinum spores. High-acid foods (fruit) need less severe heat.
Key Fact: Freezing: stops microbial growth at -18°C (microorganisms are dormant, not killed). Ice crystals form — slow freezing creates large crystals that damage cell walls (affecting texture), fast freezing creates small crystals with less damage. Blanch vegetables before freezing to deactivate enzymes.
Key Fact: Chilling: storing food at 0-5°C slows microbial growth. Fridge temperature should be 0-5°C. High-risk foods (cooked rice, meat, dairy) must be chilled within 90 minutes of cooking.

Practice (10 minutes)

Q: explain the key ideas of food preservation

Answer:

Plenary (5 minutes)

Explain Back

Your student teaches the key points back to you without looking. Fill any gaps immediately.

Lesson 3: Application: food preservation

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Recall the key terms: key terms from food preservation. Define each in one sentence.

Main Content (35 minutes)

Parent/Teacher Guide: Let your student attempt each question alone first, then compare with the model answer. Award method marks for correct working even if the final answer is wrong.

Work through the practice questions on the revision notes page for this topic.

Plenary (5 minutes)

Error Review

Review any questions answered incorrectly. Identify whether the error was knowledge, method, or reading the question.

Lesson 4: Exam Practice: food preservation

Duration: 50 minutes

Starter Activity (5 minutes)

Command Words

Review what these command words require: state (one point), describe (say what happens), explain (say why), compare (both sides), evaluate (judgement).

Main Content (35 minutes)

Extended Answer

Extended question: Full-Mark Response Compare three different methods of food preservation, explaining how each works and its effect on food quality. [12 marks] <div class="

Freezing, drying, and pasteurisation are three common preservation methods that work through different mechanisms and have different effects on food quality. Freezing works by reducing temperature to -18°C, at which point microorganisms become dormant and enzymatic activity is drastically slowed. Water freezes, immobilising the food's contents. However, ice crystal formation damages cell walls — slow freezing creates large crystals that rupture cells, causing texture changes (e.g. soft strawberries, tough meat). Fast freezing (blast freezing) minimises this damage. Nutrients are largely preserved, though some water-soluble vitamins may be lost in drip loss on thawing. Drying removes moisture, reducing water activity below the level microorganisms need for growth (below 0.6 for most). Without available water, bacteria, moulds, and yeasts cannot grow. Drying concentrates flavours and nutrients per gram but significantly alters texture — dried foods are hard and require reconstitution. Some vitamin C is lost through oxidation during the drying process. Dried foods are lightweight and shelf-stable at room temperature. Pasteurisation uses heat (72°C for 15 seconds) to destroy pathogenic

Exam Tips: Always explain HOW the preservation method works (what it does to microorganisms) | Link each method to the conditions microorganisms need for growth | Consider the effect on nutritional and sensory properties
Common Errors: ✗ Freezing kills bacteria. ✓ Freezing stops bacterial growth by making microorganisms dormant, but most bacteria survive freezing. When food thaws, bacteria resume growing. This is why thawed food must be handled carefully and consumed promptly. ✗ All preserved foods last indefinitely. ✓ Preservation extends shelf life but not indefinitely. Frozen foods deteriorate over time (freezer burn, quality loss). Canned goods eventually degrade. Dried foods can absorb moisture and spoil. Each preservation method has practical limits. ✗ Pasteurisation and sterilisation are the same. ✓ Pasteurisation (72°C/15 sec) kills pathogens but not all microorganisms or spores — products need refrigeration. Steri
Stretch & Challenge (Grade 8-9):
  • Synoptic links: explain how food preservation connects to another Food Preparation and Nutrition topic you have studied
  • Real-world: research one real-world use or example of food preservation
  • Critical: "What are the limitations of the models used in food preservation?"

Plenary (5 minutes)

Assessment Criteria
  • Got it: Confident explanation + correct worked examples
  • Getting there: Main points OK, needs support with detail
  • Not yet: Confused on key concepts - re-run Lesson 2

Homework & Consolidation

Recommended Resources

🎓 Smart Lesson (Guided)