Microbes and food 1. Menu - you are what you eat
Whipped cream photo
Picture 1.18a You can eat whipped cream as it is or make it into a chocolate mousse.
1.18 Cream
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What is it?
Cream is made by centrifuging milk. This separates off the watery part and concentrates the fat. The different types of cream have different fat contents, ranging from 12% in half cream to around 55% in clotted cream.
How does it spoil?
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Cream is usually pasteurised or sterilized and keeps well in the fridge. Its quality depends on the effectiveness of its heat treatment. The action of spore forming bacteria is similar to that in milk, with Bacillus cereus sometimes causing ‘bitty cream’. If contaminated after treatment, lipolytic microbes such as Pseudomonas bacteria or yeasts can produce some strong and unpleasant odours and tastes.

Cream should be kept in the fridge at 0-5°C and consumed quickly after being opened. Bakery products like cream buns should be eaten as soon as possible after purchase.

Can it be harmful?
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Poor hygeine photo
Picture 1.18b Scratching an itchy nose whilst preparing food can lead to food poisoning.
Cream is generally safe because it has been pasteurised or sterilized. However, fat has a protective effect on micro-organisms and stronger heat treatments are necessary than for liquid milk. Most food poisoning associated with cream is due to contamination with harmful bacteria in the kitchen.

The picture shows an example of poor personal hygiene that could lead to food poisoning. The cook has an itchy nose whilst making a cream dessert and can’t resist rubbing it. Staphylococcus aureus bacteria which sometimes live harmlessly on the skin or in the nose get on to her fingers, and from there on to the spoon being used for stirring the cream. In warm conditions, the bacteria will grow and anyone eating the food could become ill. Cases of salmonellosis are also often associated with cream – in this case due to cross-contamination from foods such as raw meats.