FND 100: Fruits and Vegetables Part 2 Flashcards
What are good sources of ascorbic acid?
Citrus fruits, melons, and strawberries
Potatoes
Vegetables
Solubility of ascorbic acid
Water soluble and highly susceptible to oxidation
Loss of ascorbic acid with processing
Losses with cooking and processing and is susceptible with oxidation
L-ascorbic acid vs. L-dehydroascorbic acid
L-ascorbic acid is functionally antioxidant when it is oxidized it is known as L-dehydroascorbic acid
Function of L-dehydroascorbic acid
Need to reduce molecule back to OG because it no longer has aspect of vitamin C
What is all purpose flour fortified with?
B vitamins are removed in the process of producing all purpose/ cake flour
Why is flour fortified with B vitamins?
Done for nutrition and also due to folic acid for the prevention of neural tube defects
What contributes the most ascorbic acid?
Fruits
What do potatoes and sweet potatoes contribute?
Ascorbic acid
What do vegetables contribute ?
Vitamin A and ascorbic acid
What do dry beans and pears contribute?
Niacin and thiamine
What does flour contribute?
Thiamine and niacin
How does vitamin A occur?
In its precursor form such as beta carotene in ‘orange-coloured’ crops as well as dark green leafy vegetables
Is vitamin A water soluble or lipid soluble
Lipid soluble
Where is chlorophyll found?
In chloroplast (which also contain lipid) since chlorophyll is lipid soluble
Carotenoids and chlorophyll
Carotenoids are masked in dark leafy greens due to a larger quantity of chlorophyll in chloroplasts
Why does the high level of provitamin A activity in beta carotene make sense?
Because cleaving bonds right down the center will give two molecules of vitamin A for every molecule of beta carotene.
How many beta carotenes do you need to get 1 vitamin A
Need 6 beta carotene to get 1 vitamin A so not perfectly efficient coversion
Why do you need so many beta carotenes for 1 vitamin A
Your body is not perfect so in order to get 1 molecules l of vitamin A from your food you need 6 molecules of beta carotene
What has the highest provitamin A activity?
Beta carotene
What has the lowest provitamin A activity?
Lycopene (tomato) has basically zero provitamin A activity
Where are B-complex vitamins present?
Present in moderate amount in fruits and vegetables fortified at higher levels in flour
What do carotenoids include?
Beta carotene
Lycopene
Astaxanthin
Beta carotene colour
Orange, yellow colour
Lycopene colour
Red
Asthaxanthin colour
Red
What influences the pigment of our fruits and veggies?
Boiling carrots, sweet potatoes, or squash which can influence and decrease the intensity of the colour
What is the intensity of colour related to?
The bond geometry of the molecule
How is intensity of colour affected?
Conversion of bond geometry
Impact of acids
Acid coverts from trans to cis
What is a conjugated system?
Each double bond is connected to the next group. Different to db structure of fatty acids.
Example of nonconjugated systems
Unsaturated fatty acids like linolenic or linoleic are in non-conjugated systems. There is a carbon in between neighbouring double bonds
Fatty acids vs carotenoid structure
Fatty acids has carbon in between. No carbon in between carotenoids
Why are fruits and vegetables susceptible to oxidation?
Due to conjugated double bond system
Why are carotenoids susceptible to oxidation?
Because of the conjugated double bond structure
What happens if beta carotene colour decreaes?
It means it was used as an antioxidant
Why can beta carotene act as an antioxidant?
Because of the double structure and more specifically the antioxidant ability is due to the capacity of them to act as singlet oxygen clenchers
What is singlet oxygen?
Reactive form of oxygen that may damage DNA or cells
Solubility of chlorophylls
Fat soluble
What are the two forms of chlorophyll
Chlorophyll a and b
Colour of chlorophyll a
Blue-green
Colour of chlorophyll b
Green
What happens to chlorophyll with extensive heating and presence of acid?
With extensive heating and presence of acid the pigments can be altered to pheophytin
Pheophytin colour
Dull, olive green instead of the typically bring green of the fresh veggies
What do typical heme structures do?
Bing magnesium in its structure
What is the phytyl tail of chlorophyll structure
Is a hydrocarbon which makes it lipid soluble
What happens to the structure of chlorophyll when it is exposed to an acid?
The molecule of magnesium is removed and replaced with two hydrogen atoms from the acidic environment and then pigment changes to olive green
Why does the pigment change?
Because hydrogen will not interact with core structure in the Sam way that one molecule of magnesium would
How can loss of chlorophyll colour be prevented?
Through use of a base to preserve bright green colour
What does a base do to veggies?
Destroys cellulose and hemicellulose