The chemistry of food

This project should take approximately five hours to complete in full, but you could extend this if you add molecular modelling practice. The activities were initially created for 14–16 year-old learners but can be adapted for other age groups.

Use the resource in a sequence of timetabled chemistry lessons, STEM clubs or during an activity day. 

Learning objectives

• Carry out at least two analytical procedures successfully to obtain reliable results.
• Use a minimum of one set of results to calculate an unknown quantity.
• Summarise at least two careers linked to food that use chemistry.

Guidance notes

Use the PowerPoint to introduce and provide the background science to each of the three practical activities. Carry out the food analysis experiments as a circus of three stations with small groups or pairs of learners circulating after approximately one hour at each station. 

Activity 1: identifying food colourings in soft drinks

In Activity 1, learners find the R_f values of a range of food colourings through thin-layer chromatography (TLC). They then analyse concentrated extracts from soft drinks to find which food colourings are present by comparing the R_f values. Once learners have completed the practical work, they summarise their findings in a memo to a drinks manufacturer. This consolidates their learning and focuses on the career of a food analyst.

Activity 2: finding the vitamin C content of fruit juices

Learners use the reaction between iodine and vitamin C to find the vitamin C content of fruit juice in Activity 2. They carry out a titration, then use their results in structured calculations to determine the vitamin C concentration in the juice.

In their role of food analyst, they write to the juice manufacturer to explain their results with reference to claims on the juice’s nutritional labelling.

Activity 3: finding the iron content of food

Visible absorption spectroscopy is used to find the iron content of some food samples. Learners produce a calibration curve using standard iron solutions, then use this to find the iron content of the unknown samples. 

If you do not have the kit available you could skip this activity or use an alternative, such as Project 2: phone-y science. This allows learners to use an alternative to a spectrophotometer and you could adapt it for testing iron solutions instead of different blackcurrant concentrations.

Challenge activities

Use current news items or reports for learners to read about teenage diets (eg too much sugar or caffeine; not enough iron/vitamins and so on). Learners could write their own summary articles and make suggestions for policymakers.

There are two questions, one on titration and one on chromatography, in the student workbook that learners could complete as an extension or homework activity. 

Find the answers to all the activities in the teacher notes and on the slides. 

Careers

The Chemistry for All project found that recognising the value and importance of chemistry, and appreciating how it can lead to interesting and well-paid jobs strongly related to learners’ future aspirations.

Use the videos embedded in the PowerPoint to introduce learners to four scientists who use their chemistry skills, knowledge and qualifications in their careers. Share our careers website, A Future in Chemistry, with learners to discover the different study options available to them, find more job profiles of chemists making a difference and try our career options game. 

Health and safety

Read our health and safety guidance and carry out a risk assessment before running any live practical. 

The safety equipment suggested is in line with CLEAPSS requirements. For non-hazardous substances, wearing lab coats can help to protect clothes. The safety rules might be different where you live so it is worth checking local and school guidance. Remind learners they should never eat or drink in a science laboratory.

Find more projects like this, plus shorter activities suitable for single science lessons or clubs on our Outreach resources hub.