Humans have used microbes for the preservation and production of food for centuries. The production of acid by bacteria acts as a preservative in many foods, like yogurt and pickles. The production of alcohol by yeasts is used in the making beer and spirits. The carbon dioxide produced during alcohol fermentation

Humans have used microbes for the preservation and production of food for centuries. The production of acid by bacteria acts as a preservative in many foods, like yogurt and pickles. The production of alcohol by yeasts is used in the making beer and spirits. The carbon dioxide produced during alcohol fermentation also adds fizz to beverages like beer and sparkling wine.

In order to practice culturing microbes at home, you are tasked with preparing a food item that requires the culture of microbes! There are many options, but the easiest options would be yogurt using store bought yogurt as starter culture, bread using store bought yeast, or sourdough bread using a native yeast culture. More challenging options might be pickles, kombucha, or beer. Please consider the time constraints of the semester when choosing what  food item you will prepare. This a full lab report. Your write up must have full sentences that make up paragraphs. The bulleted list below is a detailed outline to help you organize your paper. Writing one-word answers for each bullet point or a sentence for each bullet point will result in a failing grade. The project must include the following:

 

  • Introduction (20 points):
    • Identify the kind of food being prepared and the historic function
      • preservation, portability, profit, edibility, health benefits
    • Provide information the organism or organisms used for fermentation
      • Domain, genus and species
      • Metabolic pathway utilized
      • Reactants and Products
      • Preferred habitat
      • thermophile, mesophile, halophile, osmophile, etc
    • What role does the microbe play in food production
      • leavening, acid, fizz, etc
    • How do you expect your end product to come out?
      • For this item, there is no right or wrong answer. This could be your first foray into baking or you could be a seasoned chef. You might be choosing a simple recipe and making no changes, or you could be altering a recipe to make it your own to see how it turns out.
    • Methods (15 points)
      • The full recipe in your own words with a citation
        • Indication of any modifications made to the recipe
      • What tools you will be using?
      • How will you incubate your culture?
        • For yogurt or yeast bread, I recommend incubating in an oven that is turned off with the oven light on to provide some warmth.
      • Photograph of reactants (the ingredients).
    • Results (10 points)
      • Photograph of your finished product with caption.
      • Description of your finished product
    • Discussion (35 points)
      • Media for the culture of microbes can be broken down into two broad classes, defined and complex. Was your recipe for defined or complex media? Why?
      • The ingredients in microbiological media can be broken down into 3 main categories. See page  236 in the lab manual for full descriptions.
      1. Nutritional components
        • What was added to the recipe to support the growth of microbes?
      2. Inhibitors
        • What was added to slow the growth of microbes or to stop the growth of undesirable organisms?
        • Tip (bread): Salt is often added in bread making to slow the fermentation process to increase the flavor profile of bread.
        • Tip (yogurt): Temperature is used to modulate microbial activity. In some cultures, thermophilic homolactic fermenters produces lactic acid but when refrigerated, mesophilic heterolactic fermenters produce other compounds that alter the flavor.
      3. Substrates
        • Usually the specific compound used for microbial growth.
        • In bread making, this is usually table sugar (sucrose) and in yogurt this is usually milk sugar (lactose).
      4. Indicators
        • Usually indicators are dyes that change color in response to changes in pH or redox states.
        • Most food products do not include a color changing indicator.
        • However, in both yogurt and bread making, there are changes that indicate microbial activity has taken place. What are they?
  • What steps involved with the production of your food product had analogous laboratory practices?
  • What were the analogous lab practices and why are they analogous?
    • Example:In home canning, using a pressure cooker is analogous to autoclaving media. The high heat and liquid water kills spore forming bacteria.
    • Sterilizing, enrichment culture, selective media, and selective growth conditions (temperature) are all laboratory practices that likely had an analogous practice in the kitchen.
  • Identify one thing you could do differently and how it would change the outcome of your food product? Would this change improve the product or would it be a catastrophic mistake

 

 

Reference no: EM132069492

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