Bio-Technology (Biology Summary Notes)
Bread Production
- Flour, fat, salt, water and yeast are mixed with dough.
- The dough is kneaded (folded rapidly).
- The dough is covered and left in a warm place to allow the yeast to respire anaerobically.
- Carbon dioxide bubbles are trapped in the dough and cause a leavening (rise).
- The dough is then baked to kill the yeast and evaporated the alcohol.
- The bread is cooled and ready to be packed.
Beer Production
- Malting: the seeds of barley are soaked in water and allowed to germinate. Enzyme produced by germination convert stored starch and proteins into sugar and amino acids.
- Milling: the malted barley is broken up.
- Mashing: hot water is added to the grains to soften them and extract a nutrient rich liquid (also known as Wort).
- Boiling: the female flowers of the hop plants are mixed with the wort to give flavor, the mixture is heated at a high temperature and then . . allowed to cool.
- Fermentation: yeast is added. This converts sugar to ethanol and carbon dioxide.
- Filtration: the alcoholic liquid is extracted. This is the finished beer.
Wine Making: Wine making is similar to beer making only the source of sugar is different. Wine is made from the sugar found in grapes.
Vinegar:
- Vinegar is made from the oxidation of acetic acid bacteria of ethanol in wine, cider, beer, or any other liquid containing alcohol.
Cheese Making:
- Curdling: For cheese production, milk has to be separated into solid curd and liquid whey. This requires an acidic pH. This is obtained by fermentation. The Lactobacillus bacteria are added to the milk and turn lactose (in milk) into lactic acid.
This production of lactic acid reduces the pH which makes the curdle. The enzymes rennin and chymosin aid in this process of curdling.
- Processing the Curd: For soft cheeses the process of now ready and they are packaged but for hard cheeses the curd is now cut into small cubes, this allows water to drain from the individual pieces of curd. Some hard cheeses are also heated in temperatures of around 35°C - 55°C.
Salt is then added to the curd, this: enhances the flavor, preserved the cheese from spoiling, draws moisture from the curd and firms up cheese texture in interaction with its proteins.
Yoghurt making:
- Pasteurised milk is thickened with skimmed milk powder.
- The temperature is kept at a constant 45°C - 48°C. A warm temperature is important because: it helps thicken the milk protein, it reduces the oxygen level and is the ideal temperature for growth of bacteria.
- A yogurt culture is added to the milk and mixed well. This culture will have two types of bacteria that are Lactobacillus bulgaricus and Streptococcus thermophilus. These bacteria are responsible of the lactic fermentation of yoghurt.
- The mixture is allowed to set and coagulate at the temperature of 45°C.
Silage:
- Silage is fermented, high moisture fodder that can be used to feed ruminants or used as a bio fuel, or feedstock for anaerobic digesters.
- The plant material is first collected and chopped into small pieces, it is then placed in a silo or piled up in a large heap covered with plastic. It is compressed several times to remove as much of the oxygen present.
- The silage then undergoes anaerobic fermentation. This converts sugars into acids.
Industrial Fermenters / Bioreactors
- Bioreactors are used when microorganisms are used to ferment and produce foods and other products in large production.
- Advantages:
Ø Reactions can be carried out at low temperatures.
Ø There would be less waste and less need for purification of products since the organisms would have been artificially selected.
Ø The organisms can be genetically engineered sot that they can manufacture products useful to humans that are not normally produced.
Antibiotic production:
- The antibiotic penicillin is also produced in a bioreactor. A culture of fungus Penicillium is added to the fermenter.
- The pH of around 6.5 was maintained, and a temperature of around 30°C was kept.
- The fermentation of Penicillium takes around 6 days.
- Flour, fat, salt, water and yeast are mixed with dough.
- The dough is kneaded (folded rapidly).
- The dough is covered and left in a warm place to allow the yeast to respire anaerobically.
- Carbon dioxide bubbles are trapped in the dough and cause a leavening (rise).
- The dough is then baked to kill the yeast and evaporated the alcohol.
- The bread is cooled and ready to be packed.
Beer Production
- Malting: the seeds of barley are soaked in water and allowed to germinate. Enzyme produced by germination convert stored starch and proteins into sugar and amino acids.
- Milling: the malted barley is broken up.
- Mashing: hot water is added to the grains to soften them and extract a nutrient rich liquid (also known as Wort).
- Boiling: the female flowers of the hop plants are mixed with the wort to give flavor, the mixture is heated at a high temperature and then . . allowed to cool.
- Fermentation: yeast is added. This converts sugar to ethanol and carbon dioxide.
- Filtration: the alcoholic liquid is extracted. This is the finished beer.
Wine Making: Wine making is similar to beer making only the source of sugar is different. Wine is made from the sugar found in grapes.
Vinegar:
- Vinegar is made from the oxidation of acetic acid bacteria of ethanol in wine, cider, beer, or any other liquid containing alcohol.
Cheese Making:
- Curdling: For cheese production, milk has to be separated into solid curd and liquid whey. This requires an acidic pH. This is obtained by fermentation. The Lactobacillus bacteria are added to the milk and turn lactose (in milk) into lactic acid.
This production of lactic acid reduces the pH which makes the curdle. The enzymes rennin and chymosin aid in this process of curdling.
- Processing the Curd: For soft cheeses the process of now ready and they are packaged but for hard cheeses the curd is now cut into small cubes, this allows water to drain from the individual pieces of curd. Some hard cheeses are also heated in temperatures of around 35°C - 55°C.
Salt is then added to the curd, this: enhances the flavor, preserved the cheese from spoiling, draws moisture from the curd and firms up cheese texture in interaction with its proteins.
Yoghurt making:
- Pasteurised milk is thickened with skimmed milk powder.
- The temperature is kept at a constant 45°C - 48°C. A warm temperature is important because: it helps thicken the milk protein, it reduces the oxygen level and is the ideal temperature for growth of bacteria.
- A yogurt culture is added to the milk and mixed well. This culture will have two types of bacteria that are Lactobacillus bulgaricus and Streptococcus thermophilus. These bacteria are responsible of the lactic fermentation of yoghurt.
- The mixture is allowed to set and coagulate at the temperature of 45°C.
Silage:
- Silage is fermented, high moisture fodder that can be used to feed ruminants or used as a bio fuel, or feedstock for anaerobic digesters.
- The plant material is first collected and chopped into small pieces, it is then placed in a silo or piled up in a large heap covered with plastic. It is compressed several times to remove as much of the oxygen present.
- The silage then undergoes anaerobic fermentation. This converts sugars into acids.
Industrial Fermenters / Bioreactors
- Bioreactors are used when microorganisms are used to ferment and produce foods and other products in large production.
- Advantages:
Ø Reactions can be carried out at low temperatures.
Ø There would be less waste and less need for purification of products since the organisms would have been artificially selected.
Ø The organisms can be genetically engineered sot that they can manufacture products useful to humans that are not normally produced.
Antibiotic production:
- The antibiotic penicillin is also produced in a bioreactor. A culture of fungus Penicillium is added to the fermenter.
- The pH of around 6.5 was maintained, and a temperature of around 30°C was kept.
- The fermentation of Penicillium takes around 6 days.