Food production- microorganisms

• Role of yeast in bread making 


  In bread making, yeast produces enzymes that break down starch in flour, releasing sugars. These sugars are then used by yeast for anaerobic respiration, producing carbon dioxide that causes the dough to rise, resulting in the formation of bread during baking.
• What happens to ethanol produced by yeast to make sure bread doesn’t contain ethanol 


  Any ethanol produced by yeast during anaerobic respiration in bread making is evaporated during baking, ensuring that bread does not contain alcohol
• How does yeast contribute to the rising of bread dough


  Yeast produces carbon dioxide during anaerobic respiration, which gets trapped in small air pockets in the dough, causing it to rise (increase in volume), ultimately resulting in the light and fluffy texture of bread after baking.
• What happens to yeast during baking


  Yeast is killed by the high temperatures used during baking, preventing further respiration, while any ethanol produced as a waste product of anaerobic respiration is evaporated, ensuring that bread does not contain alcohol.
• Define the term fermentation.


  Fermentation is a metabolic process carried out by microorganisms like yeast, involving the breakdown of sugars into simpler compounds, often accompanied by the production of energy, ethanol, carbon dioxide, or other by-products under anaerobic conditions.
• How can the effect of temperature on yeast fermentation be investigated?


  The effect of temperature on yeast fermentation can be investigated by measuring the rate of carbon dioxide production, which correlates with the rate of anaerobic respiration, at different temperatures using a water bath setup with yeast and sugar solution, observing the number of bubbles produced within a fixed time period.
• What role does temperature play in yeast fermentation?


  Temperature affects the rate of yeast fermentation by influencing enzyme activity. Higher temperatures closer to the optimum temperature of yeast enzymes increase enzyme activity, leading to faster fermentation rates, while temperatures beyond the optimum can cause enzyme denaturation and decrease fermentation rates.
• What is the purpose of adding oil to the yeast and sugar solution in the experiment investigating the effect temperature on yeast fermentation?


  Adding oil to the yeast and sugar solution creates a barrier that prevents oxygen from entering the solution, thereby inhibiting aerobic respiration in the yeast and promoting anaerobic respiration, which is essential for observing the effect of temperature on yeast fermentation.
• enzyme activity in yeast fermentation increasing with temperature 


  Higher temperatures closer to the optimum temperature of yeast enzymes increase enzyme activity, facilitating faster fermentation rates due to increased rates of enzyme-controlled reactions involved in anaerobic respiration.
• Why is limewater used in the experiment investigating the effect temperature on yeast fermentation?

  Limewater is used in the experiment to detect the production of carbon dioxide, which is a by-product of yeast fermentation. When carbon dioxide bubbles through limewater, it forms a cloudy precipitate of calcium carbonate, indicating the release of carbon dioxide during yeast fermentation.
• What happens to carbon dioxide production if the temperature exceeds the optimum for yeast enzymes?

  What happens to carbon dioxide production if the temperature exceeds the optimum for yeast enzymes?
• What are some advantages of using bacteria in food production?


  Bacteria are useful in food production due to their capability toproduce complex molecules, such as enzymes for milk fermentation, and their rapid reproduction, which accelerates the production of desired chemicals, enhancing efficiency in processes like yoghurt making.
• What type of bacterium is typically used in yoghurt production?


  Lactobacillus is the specific type of bacterium commonly used in yoghurt production, as it plays a crucial role in fermenting milk sugars (lactose) into lactic acid, thereby souring and thickening the milk to form yoghurt while also acting as a preservative due to the increased acidity.
• pasteurised milk involvement in yoghurt production 


  In yoghurt production, milk is pasteurised at temperatures between 85-95°C to eliminate unwanted bacteria that could interfere with the fermentation process, ensuring the growth of Lactobacillus bacteria and preventing contamination or spoilage of the yoghurt.
• Define fermentation in the context of yoghurt production.


  Fermentation in yoghurt production refers to the metabolic process carried out by Lactobacillus bacteria, where milk sugars (lactose) are converted into lactic acid, resulting in the souring and thickening of the milk to form yoghurt. Fermentation also helps preserve yoghurt by lowering pH and inhibiting harmful microorganisms.
• What affect will the conversion of lactose to lactic acid have on the pH during yoghurt production?


  The conversion of lactose into lactic acid by Lactobacillusbacteria will Lower the pH during yoghurt production .
• How does temperature control affect yoghurt production?


  Temperature control is critical in yoghurt production as it facilitates the optimum growth and activity of Lactobacillusbacteria.
• What Lactobacillus bacteria coverts during yoghurt production 


  Lactobacillus bacteria convert lactose into lactic acid during yoghurt production through fermentation.
• Why is it essential to sterilise equipment in yoghurt production?

  Sterilising equipment in yoghurt production is essential to eliminate unwanted bacteria, ensuring a clean environment for Lactobacillus bacteria to thrive during fermentation without competition or contamination, thereby maintaining the quality and safety of the yoghurt product.
• Define the term fermenter.


  Fermenters are containers used to grow (‘culture’) microorganisms like bacteria and fungi in large amounts.
• List uses of an industrial fermenter.

  can then be used for:

  • Brewing beer.
  • Making yoghurt. 
  • Making mycoprotein. 
  • Producing genetically modified bacteria and moulds that produce antibiotics. (e.g. penicillin) or other medicines.
  • Other valid examples.
• What is the function of the stirring paddles inside the fermenter?


  The stirring paddles agitate the contents of the fermenter ensuring that microorganisms, nutrients, oxygen, temperature and pH are evenly distributed throughout.
• What is the function of the cooling jacket around the fermenter?


  The cooling jacket runs cold water around the outside of the fermenter. This helps to cool the contents to avoid overheating and to keep the temperature as close to optimum as possible. The microorganisms release heat energy as they carry out exothermic respiration so without the cooling jacket it would easily overheat.
• How is the fermenter cleaned between uses?


  The fermenter is cleaned using scorching hot steam. This is just water. No other chemicals are used. It is important to avoid using any harsh anti-microbial chemicals such as bleach because it could contaminate the product inside the fermenter and potentially kill the useful organisms inside the fermenter.
• How do the microorganisms in the fermenter get the nutrients they need to survive?


  The microorganisms get their nutrients into the machine through pipes. The necessary biological molecules for the metabolism and reproduction of the organisms, such as glucose, are provided.
• How are the temperature and pH monitored inside the fermenter?


  The temperature and pH are monitored through probes on the inside of the machine that connects to a computer where the readings can be viewed and adjustments made if the readings stray from the optimum.