The rest of the course Flashcards
Which are the 5 most common food colour additives in Sweden?
Caramel, beta-carotene, Annato extract (carotenoid), anthocyanins and vitamin B2 (riboflavin)
Name some natural colors
Tetrapyrroles (heme, chlorophylls), Terpenoids (carotenoides), Flavanoids and betalanines
What give the red color in meat
The conjugated double-bond, also the oxidation state of iron
What happens to myoglobin when reacting with oxygen and nitrite and when it is oxidized and heated
Oxygen + myoglobin becomes oxymyoglobin which is Bright red. When this one is heated it becomes methmyoglobin which is Brown. When myoglobin is oxidized it also creates this Product. If both methmyoglobin and myoglobin is treated with NO it turns into a nitrosomyoglobin which is Bright red.
Which two compounds can make meat red
CO and NO
In which way do the partial pressure of oxygen affect myoglobin
The larger the oxygen partial pressure, the more oxymyoglobin. Where the oxygen is low (where plastic touch meat) there is high levels of methmyoglobin. Where it is none oxygen the deoxymyoglobin is present which give a Purple red color (vacuum pack).
How is the chlorophyll affected as a color?
It has a Mg in the middle (as heme has iron). If this is lost it becomes Brown; often in pH <6. If the pythol Group is removed (enzymatic) it becomes more hydrophilic and stable.
What can be done to preserve the green chlorophyll color
Higher pH, High temp/short time processing, transform to chlorophyllide (E140) or substitute the Mg to Cu (Boston gurka, Wakame)
Name some commonly used terenoids
- carotenes (lycopene- red in tomatoes, beta-carotene- orange n carrots)
- Xanthophylls (Lutein- yellow in egg yolk, astaxanthin- yellow egg yolk and salmon, bixin)
Describe the properties of terpenoids
Yellow to orange/red, soluble in lipids, sensitive to oxygen, radicals and light (oxidation)
Name a common flavanoid, the a
Anthocyanidins: give a red/blue/lilac color in blueberry and a lot of other berries and fruits. Affected by pH. At low it is red (and if oxidized it becomes colorless). When the pH increases it goes to violet (neutral) and lastly blue when basic.
What effect do sulfite have on anthocyanins
When sulfite binds it creates a colorless compound. The red color can be preserved by adding other polyphenols that bind to same Place as in red wine/cocktail cherry. White wine have sulfites (can be used to bleach red wine stains)
Name Another flavonoid, the p
Proanthocyanidins: colorless but easily oxidized to red-brownish color
Whats the properties of condensed tannins
Give a brownish color and in nature they occur in polymers, first detected in cocoa beans, ability to precipitate proteins: give that dry taste, inhibit metals (coffee inhibit iron uptake), antioxidant. Often present in tea.
Describe the properties of betalaines
red, heat sensitive, sensitive to oxygen and light - becomes brownish, not so affected by pH
Name a common synthetic colour
Azo-colours: used with restrictions, some are banned in the EU because of the effect in Children
Whats the defintion of vitamins
a Group of organic compounds, 13 recognized in human nutrition, essential in small amounts
Which vitamins are fat-soluble
Vitamin A, D, E, K and caretenoids
Which vitamins are water soluble
VItamin C and B
Whats a vitamer
a compound with similar biological properties to Another but some diff. exists in the chemical structure, ex. retinol (Vit. A), ergo- and colecalciferol (vit. D)
Whats a provitamin
a naturally occuring compound which can be converted into a vitamin by normal body metabolism, ex caretenoids
Whats a problem when analyzing folic acid
Only the reduced form can be detected
Name some precautions taken when sample prep. before analysis
Yellow light, homogenize the sample, do not use Stainless steel, nitrogen gas to prevent oxidation
Which analyze method is used for B6
There exists man diff. variants so you need to homogenize all so not all 3 needs to be detected. Detect by HPLC (fluorescence detection)