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By Sara Gray, Baylee Ruth and Krista Devane

Drying

Fermentation

• Oldest preservation method

•Bacteria, yeast, and mold are unable to grow

•Microorganisms do not grow and food does not spoil as easily

Two types of drying

1. Solar drying: uses sun's rays to dry food

2. Oven drying- uses oven to dry food

•Microorganisms consume sugars and produce acid or alcohol

•Transforms substances into simpler compounds with digestive enzymes, friendly bacteria and other nutrients

•Best achieved at 68-72°F

•When fermentation complete, must immediately can product

Canning

• Involves boiling food in can to kill all bacteria and sealing can to prevent new bacteria from getting in

• Sterilizes food so it will stay good for long period of time

•Refrigerate substance after opening it and use within recommended time

•Boiling food in can occasionally changes taste and texture

Refrigeration

  • One of the most popular ways of food preservation today
  • Slows bacterial action
  • Creates a minimum difference in the taste, texture and nutritional value on the food
  • Meat will last 6-10 days at 0° C, one day at 22° C and less than one day at 38° C

Chemistry Of Preservatives

Preservation In General

Pasteurization

•Process invented by French scientist Louis Pasteur during nineteenth century

•Destroy disease causing microorganisms (pathogens) that may be present in milk

•Increase milk safety for the consumer

• Designed to increase life of milk products

Bibliography

•Food preservation = science of preserving food by many different means

•Involves preventing bacteria growth and other micro-organisms

•Also includes processes that inhibit discoloration that can occur during food preparation

Drying Foods. Washington: Dept. of Agriculture, Office of Communication, 1976. Web.

Brain, Marshall. HowStuffWorks. HowStuffWorks.com, n.d. Web. 21 Dec. 2014

"Food Preservation." Princeton University. N.p., n.d. Web. 21 Dec. 2014.

"Safe Preserving: Fermented Foods." Safe and Healthy: Preserving Food at Home. N.p., n.d. Web. 21 Dec. 2014

"Drying Foods (Dehydrating)." Drying Food (Dehydrating). N.p., n.d. Web. 21 Dec. 2014.

"Pickled Fruits and Vegetables." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 21 Dec. 2014.

"Senior Science." HSC Online. N.p., n.d. Web. 21 Dec. 2014

"Refrigeration." Subject Matter:. N.p., n.d. Web. 21 Dec. 2014.

Freezing

Irradiation

•Freezes food so bacteria can not grow

•Invented by Charles Birdseye in 1929

•Fish, meats, poultry, citrus fruit juices and others commonly preserved through freezing

•Freezing food temperature ranges from 31’F ( -0.6’C) to 19’F (-7’C)

  • Radiation= energy moving through space in invisible waves
  • Food irradiation= ionizing radiation
  • These wavelengths project to food and destroy microorganisms that spoil and deteriorate food
  • A.K.A “cold pasteurization”
  • Uses three types of ionizing radiation sources 1. Cobalt-60 gamma sources 2. Electron beam generators 3. X-ray accelerators

Addition of Chemicals

• Mainly uses nitrates, nitrites, sulfides

•Nitrates break down into nitrites and stop bacterial growth

•Prevent bacterial growth by interrupting normal function of cells

•Prevent discoloration of foods such as dried fruit, dried, fried or frozen potatoes and "fresh" shrimp

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