Nutrition and Food Science · Secondary 3 · Food Science and Properties · 2.º Período

Properties of Carbohydrates in Cooking

Discover the physical and chemical changes carbohydrates undergo during food preparation. Focus on gelatinisation, dextrinisation, and caramelisation.

TL;DR:This topic explores the science behind cooking with carbohydrates, specifically focusing on starch and sugar. Students investigate the processes of gelatinisation, dextrinisation, and caramelisation. These chemical and physical changes are what give food its texture, flavor, and color, such as the thickening of a sauce or the browning of toast.

• MOE Syllabus Outcomes
• MOE NFS Syllabus 2.1.1
• MOE NFS Syllabus 2.1.2

About This Topic

This topic explores the science behind cooking with carbohydrates, specifically focusing on starch and sugar. Students investigate the processes of gelatinisation, dextrinisation, and caramelisation. These chemical and physical changes are what give food its texture, flavor, and color, such as the thickening of a sauce or the browning of toast.

Understanding these properties allows students to predict and control the outcomes of their cooking. This is a core component of the Food Science section of the syllabus. This topic comes alive when students can physically model the patterns of starch granules swelling and bursting through hands-on kitchen experiments.

Key Questions

1. What happens to starch when heated in liquid?
2. How does sugar change when subjected to dry heat?
3. Why do baked goods turn brown?

Watch Out for These Misconceptions

Common Misconception

Caramelisation and the Maillard reaction are the same thing.

What to Teach Instead

Caramelisation involves only sugar, while the Maillard reaction requires both protein and sugar. Hands-on comparison of heated sugar versus a glazed chicken wing helps students see and smell the difference.

Common Misconception

Starch thickens a liquid as soon as it is added.

What to Teach Instead

Starch requires heat and liquid to reach the gelatinisation point. A 'live' heating demonstration where students measure temperature against viscosity helps correct this misunderstanding.

Active Learning Ideas

Inquiry Circle

The Thickening Agent Test

Students test different starches (cornflour, potato starch, plain flour) to see which creates the clearest and thickest gel at a specific temperature. They record observations and present their 'best starch' recommendation for a fruit glaze.

60 min·Small Groups

Stations Rotation

The Browning Spectrum

Set up stations for caramelisation (heating sugar) and dextrinisation (toasting bread). Students observe the changes in color, smell, and taste at different time intervals, noting the point where 'flavorful' turns to 'burnt'.

40 min·Small Groups

Think-Pair-Share

Why Did My Sauce Lumps?

Students are given a scenario of a failed white sauce. They must individually identify the scientific reason for the lumps (gelatinisation gone wrong), discuss with a partner, and share a foolproof prevention technique.

20 min·Pairs

Frequently Asked Questions

What is the best way to teach gelatinisation?

Use a step-by-step experiment. Have students observe starch granules under a microscope if possible, or use a clear glass pot to watch the transition from a cloudy suspension to a thick, translucent gel as heat is applied.

How can active learning improve understanding of food science?

Active learning, like station rotations, allows students to see chemical changes in real-time. Instead of reading about dextrinisation, they smell the toasted bread and see the color change, which creates a much stronger mental link to the scientific term.

Why do students struggle with the term 'dextrinisation'?

It is a complex word for a simple process. Relate it to everyday 'dry heat' cooking like baking or toasting. Once they see it as 'the science of toast,' the term becomes much less intimidating.

What safety precautions are needed for caramelisation lessons?

Sugar reaches very high temperatures. Ensure students use long-handled spoons, wear aprons, and never leave the heat unattended. Using a collaborative safety checklist before starting can help reinforce these rules.