Kefir is a fermented milk drink rich in probiotics.
Explain why raw milk is heated to a high temperature (pasteurised) at the start of the kefir-making process.
The pasteurised milk is cooled to around 22 °C before the kefir grains (containing active bacteria and yeasts) are added. Explain why this cooling step is necessary.
Kefir is often fortified with calcium. Give one benefit of including calcium in the diet.
Some consumers prefer kefir made from skimmed milk rather than whole milk. Give one benefit of choosing skimmed milk kefir.
Explain why the fermentation process causes the milk to become more acidic (lower pH) and increase in thickness.
Some manufacturers add milled flaxseeds (linseeds) to kefir. Suggest the health benefits of adding flaxseeds to kefir.
74 exam-style questions on Edexcel IGCSE Biology Food production. Each one has a worked solution and a mark scheme showing where the marks go.