Surrounding a food with an edible coating serves as a unique food preservation method. The purpose of edible coatings is fourfold: Read more »

Pickling

Pickling uses vinegar to preserve foods, because the acidity of the vinegar keeps many microorganisms in check. In the Middle East, vinegar was used Read more »

Food Fermentation

Fermentation has been used both for the production and preservation of various foods for thousands of years. Laborers building the Great Wall of China in the third century B.C. were fed fermented vegetables as part of their rations. Vegetables are still commonly fermented throughout Asia, but in North America, the foods most often preserved by fermentation are cucumbers, olives, and cabbage. Read more »

Food Pretreatments

Prior to drying, some foods, such as apricots and peaches, are dipped in a sulfite solution or exposed to sulfur dioxide gas to preserve their natural color and prevent spoilage. Although sulfur protects against enzymatic browning and the loss of vitamin A and C, it destroys thiamin (vitamin B1) and may cause headaches or allergic reactions, including coma and death, in certain sensitive individuals. Read more »

Commercial Food Drying

Since sun drying takes a long time and exposes foods to the weather and to the action of insects, most foods are now dried by various commercial processes, although raisins are still sun dried. Among the commercial types of drying, the three most important are conventional (heat), vacuum (pulls the water out), and freeze-drying (ice crystals vaporize). Read more »

Dried Food Preservation 

Drying is the preservation of food by the process of removing its water, which effectively inhibits the growth of microorganisms. Bacteria and molds need approximately a 15 percent moisture level to survive, while yeast needs at least a 20 percent moisture content. Read more »

Humans have been preserving foods by drying, salting, and fermentation for over 5,000 years. Ironically, the demands of war have triggered the most monumental developments in food preservation techniques. Napoleon’s need for a safe and portable food supply for his armies in the late 1700s and early 1800s led to the discovery of canning. Read more »

Physical Changes in Food

Unlike chemical changes, physical changes in foods do not result in the formation of new compounds. A few of the common physical changes occurring in foods as they spoil are evaporation, drip loss, and separation. Read more »

Chemical Changes in Food

Chemical changes, or reactions, can also contribute to the deterioration of foods. Enzymes play a significant role in catalyzing these reactions and can be categorized depending on the substance they act on (substrate) or their mode of action. Read more »

Biological Changes in Food

Microorganisms, including bacteria, yeasts, and molds, are the prime biological factor involved in food spoilage. These tiny organisms need food to survive just as people do, so food is a natural target. The most common foods spoiled by bacteria include meat, eggs, milk, and opened canned goods. Read more »