FERMENTATIONChapter 17

Page 493

Categories

Bacteria Fungi

Yeast Mold

Common Food Bourne Pathogens Bacteria

Salmonella enteriditus Campylobacter jejuni Many, many others

Fungi Some are used in food production Other are contaminants or even toxic

Types

Bacteria = Monera kingdom Yeast & Mold = Fungi kingdom Proteolytic microbes feed off protein Lipolytic microbes feed off fats Halophilic microbes feed off high salt

concentrations All microbes need water, pH, and

temperature

Pasteurization

Liquid is heated until pathogens and some spoilage bacteria have been destroyed

Prevent disease, lengthen shelf life, can also affect milk flavor

Louis Pasteur http://youtu.be/OXdbQ1JkX7c

Bacteria

Bacteria = single celled organism

Rod-shaped bacteria = bacilli

(buh-sil-uh)

Spherical shaped bacteria = cocci

(kok-sahy)

Sprial shaped bacteria = spirilla

(spahy-ril-uh) 

Aerobic needs air Anarobic oxygen-free environment Gram stain http://youtu.be/CyyY8h1doJk http://youtu.be/MY-ad03-f0I http://www.microbiologybytes.com/video

/Gram.html article

Fungus

Aerobic, spore-producing organism that lacks chlorophyll

Not always single celled Spores = reproductive cells of fungi Explode when full – sending spores

everywhere “Food Poisoning or Witchcraft?”article pg

497

Microbes and Food

Microbes are added to foods to bring about fermentation

As microbes release their digestive enzymes the enzymes break down the food product.

By-product – carbon dioxide, acetic & lactic acid, and ethanol.

Break down large molecules – absorb smaller molecules for GROWTH AND ENERGY

3 types we will look at Yeast, Bacterial, and Mold

Yeasts

Fungi with a single-celled structure Result in the production of alcohol Creates good sources of edible microbial

protein Microbes add nutritional value Baking kills yeast, but not nutritive value

(protein, vitamins & minerals)

http://youtu.be/FqxkMqsEQI0 Alton Brown All yeast breads, alcoholic beverages, and

vinegars require yeast in the production process Most common yeast is Saccharomyces

cerevisiae = warm, moist, where ______ and/or st______

Too much sugar lower the pH of the liquid and microbes can’t reproduce

Quick rising yeast is a combination of 2 yeast strains

Starters – Make a starter

Yeast Fermentation

Warm liquid 110 degrees Fahrenheit Gluten, protein, needs to be developed –

Kneading Proofing – Enzymes released

Break down sugar, releasing ethanol (alcohol) & carbon dioxide

Carbon dioxide is trapped in gluten and EXPANDS

Baking

Baking = alcohol evaporates & yeast cells are killed

Carbon dioxide continues to expand during baking

Crust forms and protein sets If proofed too long – too much carbon dioxide

is produced Gluten is over stretched & bread is heavy or dry Too much alcohol is produced creating bad taste

http://youtu.be/ZXYZYKfjNBg

BREAD!!!Let’s make some bread!!!