B3 CGP Book Edexcel

B3 Revision

Fermentation

Fermentation is when microorganisms break down large molecules in the absence of oxygen (anaerobic conditions) to produce different substances including food and drugs.

For years the food industry has been using microorganisms to produce food.

Bacteria Ferment Milk to Produce Yoghurt…

1) The equipment is sterilised to kill off any unwanted microorganisms

2) The milk is pasteurised (heated up to 72°C for 15seconds) – also to kill any unwanted microorganisms. Then the milk is cooled

3) A starter culture of bacteria is added, and the mixture incubated (heated to 40°C) in a fermenter

4) The bacteria ferment the lactose sugar in the milk to form lactic acid. Lactic acid causes the milk to clot and solidify into yoghurt (a sample is taken to make sure it’s the right consistency

5) Finally, colours and flavours are added. Then the yoghurt is packaged

LACTOBACILLIUM BACTERIA IS USED

Soy Sauce is made by Fermentation too ..

1)Cooked soy beans and roasted wheat are mixed together

2)The mixture is fermented by the Aspergillums fungus

3)The mixture is fermented again by yeasts

4)The mixture is fermented yet again by the Lactobacillus bacterium

5)The liquid is filtered to remove any gungy bits

6)Then its pasteurised to kill off the microorganisms, and finally put into sterile bottles

Functional Foods have Health Benefits

A functional food is one that has some kind of health benefit beyond basic nutrition.

For example, it might prevent some sort of disease.

Plant Stanol Esters

•Chemicals that can lower blood cholesterol and reduce the risk of heart disease

•Some food manufacturers add them to spreads and some dairy products – people who are worried about their blood cholesterol levels may choose spreads with plant stanol esters in over normal spreads

•Stanols occur naturally in plants, but in very small quantities. So they are produced by using bacteria to convert Sterols (types of fat found in plants) into Stanols

•The spreading margarine Benocol contains stanol ester – it works by blocking the absorption of cholesterol from the gut

Prebiotics

•Some people take prebiotics, as they promote the growth of ‘good’ bacteria in the gut.

•Contain added sugars called oligosaccharides.

•They’re a food supply for ‘good’ bacteria in our gut. ‘Bad’ bacteria and humans cant digest the prebiotic – they don’t have the right enzymes

•They occur naturally in foods like leeks, onions and oats, but you cant get enough of them in a normal diet to cause significant effect. This is why some people take supplements

Probiotics

•Probiotics contain the good bacteria themselves.

•When we eat these foods, the bacteria that is lost is replaced.

•Bacteria can be lost because of poor diet, stress, food poisoning and if you are taking antibiotics

•Encouraging the growth of ‘good’ bacteria in our gut and replacing those lost may help us to keep well

•They are produced by fermentation, when bacteria ferment milk and other things

Microorganisms and Food

•Sometimes the microbial product (what…