Lab 4 Flashcards
What can cause nutrient losses?
Light, heat, air exposure or leaching into cooking water
What is a way to decrease nutrient losses via air exposure?
Cut and peel (large pieces) just prior to consumption
Where are a lot of nutrients stored?
Just beneath the skin - peeling should be avoided or left until just after cooking
What is a way to minimize nutrient loss with water?
Quick cooking methods, using minimal amounts of water
Or even where the liquid is consumed
Why should we wash fruit and vegetables?
To remove pesticide residue and surface contamination (including bacteria)
What plant foods (groups) phytochemicals found in?
Flavonoid anthocyanin, Carotenoids (lutein), lycopene, indole glucosinolate, allicin and catechins
What are herbs and their purpose?
Herbs are concentrated sources of anti-oxidants. They serve as key ingredients for flavouring purposes
What are common herbs?
Parsley, basil, dill, oregano, thyme, rosemary, mint
What are some key features of Glucosinolates?
- Very water soluble
- Better absorbed if the source is well-chewed
- Quick cooking in small quantities of water
What vegetables are rich in glucosinolates?
Brussel Sprouts, Collards, kale, watercress, turnip, broccoli, rapini, mustard greens, cauliflower
What pigment do glucosinolates contain?
Chlorophyll
What are some key characteristics of anthocyanins?
- Red to Blue colour
- Water-soluble pigment
- Vary in colour due to pH
Examples of anthocyanin-containing foods?
Berries, eggplant, red cabbage
What happens to anthocyanins in an acidic environment? In a basic environment?
ACIDIC: red
BASIC: blue, greenish-blue,black
Where is Allicin present?
Alliums such as garlic, onions, shallots and chives
What is the best source of allicin?
Freshly crushed garlic
What foods contain flavanols?
Japanese green tea, onions, grapes.
How should you prepare green tea?
8-10 minutes to extract the maximal amount of anti-oxidants
What is chlorophyll?
A large molecule that is either blue-green (a) or yellow-green (b)
How do you enhance the green colour of chlorophyll?
Blanching and then rinsing in cold water enhances the green colour. Blanching allows air to escape from the vegetable and allows for the colour to be brighter
What happens to green veggies when they are cooked?
Cell rupture and release organic acids
Plastids become permeable to the acids.
H+ ions from acids move to central Mg in the chlorophyll to form pheophytin (green-grey) or pheophytin b (dull yellow-green).
How do you minimize the formation of pheophytin?
Cook green vegetables in uncovered pan as quickly as possible to allow volatile acids to escape
What happens when greens are exposed to an alkali?
Phytyl group of sodium salt chlorophyllin can be split off. (its a pigment that is a bright green and is easily leached into cooking water
What are the disadvantages of using baking soda while cooking green vegetables?
- Destruction f B vitamin Thiamin
- Bitter taste
- Mushy texture
What happens when chlorophyll is exposed to zinc/copper?
Colour turns to bright green
What are carotenoids?
- Fat Soluble substances
- Require presence of dietary fat for proper absorption in digestive tract
What are some carotenoids?
Lutein
What are some great sources of lutein?
green leafy vegetables, green peas, broccoli and romaine lettuce
Hoe is lycopene maximized?
When cooked and consumed in the presence of fat.
What happens to lycopene when excessive heat is applied?
Reduction of colour intensity and Vit A potential
What are 2 ways that anti-oxidant food are beneficial for health?
- Prevention of oxidation
- Reduce free radicals : blood vessel disease, cancer
What happens to vitamins when foods are cooked?
Vitamins are lost
How do you blanch?
Put in boiling water for 1 minute then place in bowl of cold water
Why are green placed in water after blanching?
To keep bright green colour and to make it fresh and crisp.
What are some key differences between raw and cooked greens?
- raw greens are tougher
- cooked are softer and brighter
What is the appearance of Cholorphyll containing greens after uncovered and shocked and then uncovered, shocked and lemon juice added
1) Birght green
2) Event Brighter green
What happened to the Anthocyanin containing vegetable with pH?
Vinegar made it turn a bright red
Baking Soda made it turn a blue-purple
How do you steep different teas?
White- 80C, 2-5mins Green- 80C, 1-3 mins Oolong 80C, 2-3 mins Black- 100C, 4mins Herbal-100C, 3-6mins
