Lecture 7: Food Colors, Additives, and Processing Flashcards
Why do we process foods?
- Preservation
- Improve taste
- Increase variety of foods
- Convenience
How does preservation contribute to food safety
Used to extend the shelf life of a food by controlling the growth of pathogenic bacteria and decrease toxin formation in foods by:
- Decreasing the water activity of food
- Decrease the pH of a food (make it more acidic)
- Decrease the temp a food is stored at
What are the most important factors to control in food?
- Water content
- pH (acidity)
- Temp
Water content and food safety
- Bacteria need a high moisture content to grow
- Drying foods decreases the risk of getting sick as bacteria can’t grow on them
- Bacteria need protein to grow
pH and food safety
- pH measure the acidity of a food
- Bacteria thrive in a neutral environment (pH 7)
- Food with a pH above 8 tend to be bitter and unappealing
- Foods with a pH below 6 tend to be tart and sour
- pH below 4.6 = safety zone where bacteria can’t grow
Temperature and food safety
- Temp danger zone (40 - 140 F) = rapid multiplication of microorganisms
- Refrigeration(< 40 F) = very slow growth
- Freezing (< 28 F) = no growth
- > 140 F = death of microorganisms
Drying
- Removal of free water so bacteria can’t grow
- Through sun, air, heat, fire, or vacuum
Water activity
- Scale of 0 - 1
- Partial pressure of water above the soln normalized to the partial pressure above pure water
- Pure water has an activity of 1
- Higher activity = bacteria grows more easily
Freeze drying
Freezing of foods and subsequent removal of water from the frozen food through use of a vacuum
Smoking
- Addition of smoke and heat to preserve food
- Action of the chemicals in the wood smoke and the partial drying of food
Curing
- Addition of a chemical compound (salt, sugar, sodium nitrate) to a food to slow bacterial growth (especially in meats)
- These compounds “grab” water and hold onto it, making it less available for bacteria
Fermentation
Use of special bacteria, molds or yeasts to prevent spoilage by converting the elements of a food that spoil easily (sugar) to more stable elements that act as preservatives (alcohol, acid, CO2)
Sterilization
- Any process that removes or kills all forms of microbial life, including fungi, bacteria, viruses, spore forms
- Can be done in glass jars, cans or synthetic materials
Aseptic packaging
Process by which a sterile (aseptic) food product is packaged in a sterile container in a way that maintains sterility
Irradiation
- Exposing a food to ionizing radiation to sterilize the food
- Destroys insects, fungi, or bacteria that cause human disease or food spoilage
