Chapter 17: Fermentation: Desirable Effects Part 2

composed of carbon, oxygen, nitrogen, and hydrogen

• C, O, N, H

| - Minerals and vitamins to aid with enzyme activity

Some microorganisms can remain alive, but

| dormant, in dried conditions

0.70 or lower

by removing water, adding solutes, or by freezing

Minimum, preferred, maximum

Modertate temp

Freezing: slows enzyme activity and cell reproduction
Heating: can kill microorganisms

at 5 C to 12 C above the temperature for maximum growth

enzymatically controlled change in a food product caused by the action of microorganisms

– digestive enzymes released by the
microorganisms
– the release of by-products, such as carbon dioxide, acetic and lactic acids, and ethanol

Energy

color, texture, flavor, aroma, and pH

when nutrients broken down by digestive enzymes are absorbed by microorganisms for growth and energy

all yeast breads, alcoholic beverages, and vinegars

Saccharomyces cerevisiae

– Sugar is its main source of energy

| – It can utilize on honey, molasses, or corn syrup

– Warm liquid activates yeast
– Mixing distributes yeast evenly
– Kneading the dough develops the gluten

• Proofing

• Allows the yeast to produce enzymes that break down sugars

| - Releasing alcohol and carbon dioxide

– carbon dioxide becomes trapped in pockets throughout the dough, gluten stretches, and the dough rises
– the dough continues to rise during baking and a crust forms

flour, yeast, salt, and water

fermented juice of plant products such as grapes, honey, various fruits and dandelions

Sulfur dioxide (SO2) or potassium metabisulfite

held in anaerobic conditions for up to 4 weeks in oak barrels or stainless steel tanks

when bubbling from CO2 production stops

in barrels or vats to slowly develop the characteristic flavors

– Beers are made from fermented barley
– Bourbon is made from corn
– Rum is made from sugar cane or molasses
– Brandy is distilled wine or fermented fruit juice
– Liqueurs have a brandy base with sugar and flavorings added

1) Lactic acid fermentation
2) Proteolytic
3) Acetic acid fermentation

Fermented foods produced by bacteria whose by-product is lactic acid
Produces the other by-products of acetic acid, formic acid and carbon dioxide

the lactic acid bacterial fermentation of cabbage submerged in brine, a salt and water solution

The salt controls water activity and pulls water with dissolved sugar and nutrients to the surface

Bacteria utilize the sugar and release carbon dioxide and lactic acid into the brine

heating them in a spiced vinegar solution, refrigerating in an acid brine, or fermenting them with lactic acid bacteria

– washing the cucumbers in a chlorine solution

| – placing them in a brine with a pure culture of Lactobacillus (starter culture)

vegetables such as watermelon rinds, beets, cauliflower, okra, and onions, and even eggs

to make dry and semidry sausages

– Increased acid tenderizes the meat and adds a tart flavor

| – Fermentation, smoking, and drying prevent spoilage

Milk is pasteurized, then rennin and lactic acid bacteria are added to form curds

– Curds are cut into small cubes and heated to help the whey separate from them
– Whey is drained off and collected for use as an additive in other processed foods

– mixed with cream to make cottage cheese

| – put in presses to squeeze out excess moisture for making aged cheese

cheeses wrapped with wax are placed in curing rooms

Different bacteria or molds

refers to the strength of flavor and aroma

Develops as cheese ages

– have firmer consistency
– have more crumbly textures
– melt into sauces more readily

antibiotics, flavor compounds, and enzymes

– soy sauce, a fermented mix of soybeans and wheat
– tempeh, a soybean cake of cooked, mashed soybeans pressed into blocks, inoculated with Rhizopus molds, and wrapped in banana leaves

uses bacteria as well as fungi to produce the product

lactic acid bacteria is needed to form the product, then other microorganisms develop the flavors and textures

lactic acid bacteria ferments the product, and then a yeast starter proceeds to ferment the product

Acetic acid fermentation

• Alcohol

| - Releases acetic acid

Vinegar

produces candied citron from citron lemons

turns cacao beans into chocolate

• Microorganisms help preserve some foods

| * Fermentation offers a wider range of food options

Fermented foods tend to have a low pH and can be stored for longer periods (especially at refrigerated temperatures)

– microorganisms used
– other ingredients added
– impact of fermentation on bioavailability

Fat and calcium

Bacteria: 4.6
Molds: 1.5