Lab 9 Flashcards
What can enzyme-linked immunosorbent assays be used to detect? [3]
- Bacterial toxins
- Bacterial proteins
- Virions
How is the sample prepared for an ELISA?
Homogenized in a phosphate buffer
What does ELISA require?
- Two antibodies that bind to different structures of the target of interest (e.g., toxin).
- One antibody is conjugated covalently to an enzyme (E).
- The enzyme cleaves a colourless substrate (S) to a coloured product (P).
- The amount of product can be measured (qualitative or quantitative - via a standard curve)
What can lateral flow devices detect?
- Pathogens (virus, bacteria)
- Other contaminants (toxins)
Same concept as ELISA
What does fluorescent in-situ hybridization detect?
- Detects and locates a specific sequence on a chromosome
- Allows for direct quantification of pathogens without the need to culture the bacteria first.
How does fluorescent in-situ hybridization (FISH) work?
- Uses a piece of DNA (probe) that is complementary to a sequence in the chromosome.
- A fluorescent dye is attached to the probe
- Would have DNA probes to recognize a sequence of a portion of a pathogen like Salmonella
- Can visualize with fluorescent microscope
- Time to completion = 2-3 days including preparation of sample
Viruses have no widespread use in food production.
True or False?
True.
Viruses have widespread use in food production.
True or False?
False.
They have no use.
Microbes in our foods and drinks can: [4]
- Enhance or spoil taste and texture
- Extend or reduce shelf-life and store-ability
- Increase or decrease mineral, nutrient, caloric, or vitamin content
- Benefit or harm our microbiomes (oral, gut, skin, etc.)
Describe microbes in bread production.
- Bread has been a staple food item in many cultures for thousands of years.
- There are different ways of making bread, some of which do not involve microorganisms, but most breads utilize yeasts, which are single-celled fungi.
- These yeasts ferment sugars to ethanol and carbon dioxide.
- The carbon dioxide helps the bread to rise.
- Some breads (e.g., sourdough) also use bacteria called ‘lactic acid bacteria’, which provide the distinctive sour taste.
What happens to the ethanol? (it gets cooked out)
Describe microbes in dairy prodution.
- Many popular dairy products are produced with microorganisms.
- For example, most cheeses rely on bacteria to create a low pH and thereby help to coagulate milk proteins.
- Blue cheeses also contain molds, which give them their unique characteristics.
- Various molds, yeasts or bacteria are also added to the outside of cheeses to alter the final product (ripening and flavor).
- Yogurt production relies on bacteria, in order to thicken the milk and provide a distinctive sour taste.
- Other fermented dairy products (e.g., kefir) are made with both bacteria and yeasts.
Describe microbes in soybean products.
- Soybeans are used to create a wide array of products, particularly in East-Asian cuisine.
- Some of these products rely on fermentation.
- For example, soy sauce is made from soybeans that have been inoculated with a certain species of mold.
- Miso paste is also made with the same mold and used to make popular food items such as miso soup.
- Tempeh is a solid product, where soybeans are pressed into blocks and fermented by a different species of mold.
Describe microbes in meat and fish products.
- Fermented meat and fish products are common in some countries.
- Some salamis are made with bacteria which can lower the pH of the meat and prevent spoilage.
- Some also use mold to cover the salami for protection.
- However, not all salamis are made using fermentation.
- Fish fermented by bacteria is eaten more commonly in some Scandinavian countries and Central to East Asia.
Describe microbes and vegetables.
- Kimchi is a traditional food in Korea and is made from various vegetables which are fermented by bacteria.
- Sauerkraut is made by fermenting cabbage with bacteria that are naturally present on the leaves.
- Although the word sauerkraut is German, many countries make very similar foods under different names.
- Pickles can be made by fermenting vegetables in brine. Bacteria then create acid which lowers the pH and preserves the contents. Many pickles are instead made by directly adding vinegar to reduce the pH.
Describe microbes in condiments and sauces.
A number of condiments and sauces rely on microorganisms for their distinctive
flavors. These include:
* yeast extracts (e.g., vegemite) – created by destroying yeast cells, which then digest themselves;
* Worcestershire and fish sauces also rely on fermentation by bacteria;
* Some (but not all) hot sauces also use fermentation for a richer flavor;
* Vinegar is made using fermentation of various starting materials, such as wine, cider or fruit juice, by acetic acid bacteria.
