Applications of Biotechnological Processes The Food Industry and Fermentation

Dairy Products Yeast Extract Products Fruit Produce

Dairy Products Microbes are used to make cheese, butter, yoghurt and sour cream. Traditional Method: Products were produced through the action of indigenous bacteria present in milk.

Modern Method Milk is pasteurised to ensure safety for human consumption (kills indigenous bacteria). Microbial cultures are added to the milk. Bacteria convert the lactose in milk to lactic acid (lower pH). Bacteria are referred to as “lactic acid bacteria” e.g. Lactobacillus or Bifidobacterium

A lowering of the pH results in the protein in milk clotting and a release of flavours and aromas. A lower pH also reduces the likelihood of contamination. The specific bacteria used will determine specific properties, textures and aromas in the final product. Sometimes a second inoculum of bacteria is added to create the final, desired product

Functional Foods Functional foods are those which provide health benefits beyond basic nutrition. e.g. novel fermented drinks (also known as probiotics) provide several health benefits:

Probiotics contain “live” cultures that can re-establish themselves in our gut flora to return the individual to full health. They often do this by competing with disease causing gut flora for nutrients and by producing chemicals that will inhibit pathogen growth. Examples: Bio-yoghurts Some probiotics can shorten the duration of infant viral diarrhoea

Probiotic bacteria are able to establish themselves in the gut and synthesise vitamins. These vitamins can be absorbed through the individuals gut wall and taken up by the bloodstream. Probiotics and nutraceuticals are believed to have some anti-cancer properties, have the ability to reduce cholesterol and improve an individual’s intolerance to lactose. (nutraceuticals- food ingredients that provide health benefits)

Yeast Extract Products Yeast is used to produce alcoholic drinks, make yeast extracts (found in Bovril and Marmite) and to make food flavourings. Yeasts have a useful property known as autolysis. This is a process that results in the yeast producing enzymes that degrade itself, thus releasing particular flavours. Example: peptidase production and subsequent protein hydrolysis will create “beef flavour”

The flavour released depends on the enzyme, the stage in the yeast cell cycle and the age of the culture. Yeast flavourings are found in crisps, soups and other packet foods

Fruit Produce Fruit is used to make fruit juices, enzymes are added in their production to clarify the juice. Pectinases are produced by fungi Pectin holds/binds cell walls together, it is extracted during the fruit pressing stage in juice making. Pectin is highly viscous and can lead to problems with clarification and juice filtration Adding pectinase hydrolyses the pectin polymer to individual carbohydrate units

Arabanase Araban is also a polymer found in cell walls, it is extracted during the fruit pressing stage in juice making. It creates a haze in the pressed juice. Adding arabanase removes the hase.

Amylases Starch in pressed juice can be removed by adding amylases.

The engineered process: Fruit is also sold as itself e.g. tomatoes. Transgenic Favr Savr tomatoes have been engineered to not express a gene whose protein causes the softening of fruit. Protein name: polygalacturonase (degrades pectin within the fruit causing it to soften) The engineered process:

mRNAs are complementary to each other and so combine mRNA gene Antisense gene Engineered Tomato DNA Polygalacturonase Protein expression is prevented Original Tomato DNA

Advantage of producing tomatoes this way Tomatoes are able to ripen on the vine without softening and bruising. This gives them a longer shelf life. This also increases the number of tomatoes that are suitable to be sold, thus increasing profits/ reducing costs lost to spoilage.

Past Paper Questions 2006 Q1 2006 Q3 2005 Q1 2003 Q1