6 Flashcards
Examples of minor food constituents
CHO, Pro, Fat, water > 99% of composition of most food products.
Cranberries: sodium benzoate (natural preservative)
Carrot: (b-carotene pigment)
Vegetables oils: a-tocopherol, antioxydant
Lemons: citric acid (acidulant, pH!)
Papayas: papain (meat tenderizer = proteolytic enzymes)
Food additives definition and GRAS
Constituent isolated from source or synthesized and incorporated into commercial food products = food additives (>3000-4000).
Exception: FDA created GRAS that can be used without approval
Emulsion
Droplets of one liquid (internal phase) are dispersed in another liquid (external, continuous phase). Droplets have a tendency to aggregate to minimize contact with external phase (interfacial tension) = which can cause the breaking of the emulsion (separation into 2 phases).
Emulsifiers
Functionality of an emulsifier is characterized by its hydrophilic-lipophilic balance (HLB). Ex: monoglycerides have higher HLB than diglycerides because 2 hydrophilic/1 lipophilic. Considered a major food additive, important in foods high in fat. Lecithin, monoglyceride and diglyceride
Organic acids
Carboxylic = Citric, malic, tartaric acids are found in many fruits. Flavor + acidifying agents. Produced during fermentation by microorganisms of CHO and fermented foods (curd formation from milk). Phosphoric acid (inorganic is also an acidulants).
Acidulants
Lower pH. Naturally from fruits or synthesized. Used in fruits drinks (organic acids), rootbeer (phosphoric acid) for flavor and preservatives (lowering pH for slow microbial growth). High acid foods =< 4,6. Low acid food > 4,6(require more thermal processes). Jams and jellies and to prevent enzymatic browning in Fruits and veggies. Enzymatic browning: Polyphenol oxidase catalyzes oxidation of polyphenol compounds in plant cells. Enzymatic activity becomes uncontrolled when tissues are damaged (bruised, sliced, peeled) = leads to brown pigments (bananas, potatoes, tea). Nonenzymatic browning is Maillard reaction, so not this!!
Oxidation
Oxidation: electron is removed from molecule by an oxidant. Chain reactions that produced free radicals, which have a single unpaired electron that is really reactive(LOO, lipid-o-o called peroxy)
O2 is a strong oxidant, oxidize electron-rich compounds like:
Unsaturated fats and oils, b-carotene, chlorophyll, vit c.
Causes off-flavors, rancidity of fats/oils, color losses.
Antioxidants
Prevents or delays oxidation by scavenging free radicals and terminating free-radical chain reactions. Sacrificial antioxidants (vit c).
In living cells, antioxidants are replaced by biosynthesis or regenerated by enzymes, but in food antioxidant depletion occurs over time.
Ex: natural= lecithin, ascorbic acid, tocopherols
Synthetic = butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) = 0,01% very effective to stabilize
Abundance of pigments and color compounds in foods
Ex: 100ppm = 10^2/10^6 = 10^4/g= 10^-2/100g = 0,01%
Pigments and color
Absorbs visible light and gives color to plants and animals. Many pigments are unstable so pH, O2, other factors affect their color = often detrimental because of food acceptability.
Examples of pigments
Chlorophylls, anthocyanins, carotenoids, meat proteins, tannins
Chlorophyll
Green beans = 100 ppm of chlorophyll. Conversion of chlorophyll to pheophytin (dark green, olive brown) is caused by loss of magnesium ion. Occurs during blanching, and storage. Also affected by oxidation and changes in pH.
Anthocyanins
Three ring phenolic compounds called flavonoids. 2 rings fused together, linked to 3rd one by a single bond. Lots of functional groups (7 side chains) and they can be H, OH, OCH3. Can also have a sugar attached to OH by a glycosidic bond (glycosylation)
>500 anthocyanins have been isolated. Water soluble. Color changes with pH (stronger in acidic). Responsible for red, blue, purple in raspberries (4000ppm), blueberries, eggplants(7500ppm).
Carotenoids
Fat soluble, unsaturated molecules for orange and yellow colors. Carrots (50-100ppm). B-carotene (carrot, pumpkin) precursor of vit A (1 b carotene= 2 vit a).
Lycopene (tomatoes, red carrots)
Lutein (leafy green vegetables, color masked by chlorophyll, added to chicken feed to make egg yolks darker yellow.
Annatto: food additives in cheddar cheese, obtained from seeds of Bixa orellana tropical that contains bixin (fat soluble carotenoid) and norbixin (water soluble carotenoid)
Saffron: gives flavor and yellow color. Found in crocus stamen. One of the most expensive spices.
Pigments for salmon feed
Salmon color arises because carotenoids in their diet of shrimp and krill become incorporated in the fish flesh. 10 ppm. Farmed salmon are fed a plant based diet and would have grayish flesh so carotenoids are added to their feed (15-20% cost of the feed).
