General Microbiology Lecture 10 - Food Microbiology Part 1

Why do people study food microbiology?

• microbes used in food production

• prevent the spread of food-borne illnesses

• find efficient ways to safely preserve and prepare foods

What is fermentation?

alternative metabolic pathway, works without oxygen as terminal electron acceptor, produces much less ATP than glycolysis

Brewing or fermentation of foods with microbes has been performed for thousands of years across the globe and beer making has been around since at least 10,000 years ago. True or false

true

Who was the first to demonstrate that the conversion of sugars to alcohol was carried out by microorganisms in 1861?

Louis Pasteur

How is lambic beer made?

is fermented through exposure to wild yeasts and bacteria native as opposed to exposure to carefully cultivated strains of brewer's yeast

What is spontaneous fermentation?

is when a brewer leaves the inoculation up to whatever organisms happen to be in the air when they are fermenting

Describe the brewing process.

1. Prepare wort: Heat grain in water to turn starches into sugars.

2. Add hops: Add hops at different times to give the beer bitterness or flavor.

3. Cool wort: Use a wort chiller to cool the liquid quickly.

4. Add yeast: Add yeast to start fermentation.

5. Fermentation: Yeast creates CO2 and alcohol until it stops, then falls out of the liquid.

What is lactic acid bacteria?

bacteria that were formerly in the genus Lactobacillus, gram positive rod, can ferment lactic acid anaerobically

What is the function of lactic acid bacteria?

• used to produce fermented food

• produce lactic acid for pharmaceutical products

• production of biodegradable plastics

What is the purpose of pasteurization?

kill pathogenic microbes,but does not sterilize

All pasteurized materials will eventually _____

spoil

What is the purpose of high temperature short time (HTST)?

lowers bacterial counts and preserves taste and smell

Ultra-high temperature Pasteurization will:

render food safe for longer, but will affect taste and smell

What happens during pressure canning?

allows food to reach 116C which destroys Clostridium botulinum and endospores are killed by high heat and pressure

What is Clostridium botulinum?

gram positive endospore producing bacterium that produces a neurotoxin called botulinum

What is Botulinum?

a neurotoxin produced by Clostridium botulinum

How is botulinum used in botox?

blocks acetylcholine from being released which causes muscles to relax and wrinkles temporarily go away