lesson 14

lesson 14 - [Note: For each of the products that we will...

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[Note: For each of the products that we will review in this lecture, you are responsible for knowing the type of microorganism (bacteria, yeast or mold) that is responsible for each.] [This is another thing that you need to know about each fermentation – whether the food is preserved by acid or alcohol.] Fermentation Reaction Fermentation- the process by which microorganisms anaerobically convert carbohydrates to acid or alcohol common foods: wine, beer, vinegar, bread, cheese, yogurt, summer sausage and some pickles encourages growth of "good" microorganisms, while preventing growth of spoilage- or disease-causing microorganisms. Need controlled temp and pH As the good microorganisms consume sugars in the food product, they release acid or alcohol as a by-product, helping preserve the food and changing the food’s flavor and texture in interesting ways. standard fermentation reaction: sugar carbon dioxide + acid or alcohol. It is acid or alcohol that is produced by microbial metabolism that preserves the fermented food product, extending the shelf life and preventing some (or all) spoilage. 2 Types of Food Fermentation Natural fermentation reactions utilize microorganisms naturally existing on plant or animal food products for the fermentation reaction. The first types of fermented foods produced thousands of years ago were the result of natural fermentation. Today-sauerkraut and genuine dill pickles are produced Controlled fermentation (most fermentation reactions) -the food processor adds a particular type of microorganism so that a desired product is produced. The advantages of controlled fermentation reactions are: consistent products the ability to manipulate flavor and texture wider variety of foods can be produced. Examples: cheese, beer, bread and wine. Natural Fermentation: Sauerkraut Sauerkraut (German word meaning literally ‘sour cabbage’) bacterial fermentation. Two bacterial species are involved: Leuconostoc mesenteroides Lactobacillus plantarum. The production of sauerkraut is an example of a microbial succession as you will see. In a microbial succession, one microorganism grows and makes it suitable for growth of a second microorganism. Key Steps : Cabbage is grated or chopped and 2.5% salt is added. The added salt selects for the Leuconostoc bacteria that begin the process of converting cabbage to sauerkraut. The salt also draws juice out of the leaves; this juice contains sugars that are naturally in the cabbage leaves, sugars that the bacteria will convert to acid. The cabbage/salt mixture is placed in an air-tight container and stored at about 70 degrees F for several weeks to ferment. Cabbage is preserved by acid in the production of sauerkraut. The added salt selects for Leuconostoc mesenteroides and this bacterium grows and produces acid which drops
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lesson 14 - [Note: For each of the products that we will...

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