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
Pasteurization
- Heating a food (usually a liquid) to a specific temp for a defined length of time, then immediately cooling it down
- Reduces number of viable pathogens so they’re unlikely to cause disease
- Made popular by Nicolas Appert
Refrigeration
< 40 F
-Lowering of temp of a food to inhibit the growth of bacteria, molds and yeasts
Freezing
< 28 F
- Lowering of temps of a food to stop the growth of bacteria, molds and yeasts and to kill parasites
- Exception = listeria (can grow in cold temps)
What are food additives?
- Any substance or mixture of substances, other than the basic foodstuff, that is present in food as a result of any phase of production, processing, packaging, or storage
- Ex) salt to preserve meat, sugar to preserve fruit, vinegar to pickle veggies
What do food additives do?
- Maintain product consistency (emulsifiers, thickeners)
- Improve or maintain nutritional value (fortification of vitamins, minerals)
- Maintain palatability and wholesomeness (preservatives, antioxidants)
- Provide leavening or control pH (baking soda, tartarate)
- Enhance flavor or color (spices, dyes, synthetic flavors)
Intentional additives
- Compounds purposely added to foods to perform specific functions
- Ex) preservatives, antibacterial agents, sweeteners, colors, flavors
Incidental additives
- Constituents that result from production, processing, storage or packaging
- Typically present in trace quantities
- Ex) metal, insects, packaging material
GRAS
Substances whose use is “Generally Recognized As Safe” by experts, based on their history of use in food before 1958 or based on published scientific evidence
Name the 5 primary types of food additive agents
- Antimicrobial agents
- Sweeteners
- Coloring agents
- Flavoring agents
- Antioxidants
Antimicrobial agents
- Compounds that suppress microbial growth/activity and prevent deterioration of foods
- Most are GRAS
- Ex) benzoic acid and its salts, sorbates, sulfites, nitrates, nitrites, acetates
Sweeteners
- Natural sugars (sucrose, lactose, maltose)
- Non-nutritive sugar substitutes originally synthesized to sweeten foods for diabetics
- Popular for weight control
- Avg American consumes ~ 20 tsp of sugar a day
Aspartame
- Nutrasweet or Equal
- James Schlatter
- Made up of 2 amino acids, aspartic acid, and phenylalanine as the methyl ester
- Limited to cold, non basic foods
- FDA approved as safe except in individuals with genetic disorder phenylketonuria (PKU)
Coloring agents
- Stimulate a color that is perceived by the consumer as natural
- Offset color loss due to light, air, heat, moisture and storage conditions
- Mask natural variations in color
- Enhance naturally occurring colors
- Provide identity to foods for effect, decorative, or artistic purposes (green ketchup, cake icing)
Artificial vs. Natural coloring agents
- Certified colors (artificial) = derived primarily from petroleum and are known as coal-tar dyes
- Exempt from certification (natural) = obtained largely from mineral, plant or animal sources
Flavor
That property of a food or beverage that causes the simultaneous reaction of taste on the tongue and odor in the olfactory center of the nose
- Aroma (odor, smell)
- Taste (sweet, sour, bitter, salty, savory)
- Chemical irritation (pungency)
Flavor agents
Substance added to foods that evoke the simultaneous responses of taste on the tongue and odor in the olfactory center of the nose
Uses of flavoring agents
- Impart, augment, compliment, or modify a flavor
- Mask original flavor
- Antioxidant agents
- Anti-microbial agents
Antioxidants
- Protect against oxidative deterioration of vitamins and essential fatty acids
- Retard off-odors and extend shelf life
- Retard production of toxic by-products
Oxidation
- Can decrease the nutritional values of food
- Oxidation of unsaturated fatty acids produces rancidity
- Sources = heat (cooking), metals, oxygen exposure, light exposure (transparent packaging), storage
What makes a good food antioxidant?
- Active at low concentrations
- Non-toxic
- Able to partition interfaces (oil/water)
- Stable during processing and storage conditions
- Low cost
- Doesn’t affect flavor, odor, color
Classes of food antioxidants
- Synthetic
- Natural
