Ingredient Anatomy
Know what you are cutting.
Which part to keep, which to remove, and why it behaves the way it does.
Parts of an egg
Each part behaves differently: whites set first, yolks later, and the air cell grows as an egg ages.
- Shell: Porous calcium carbonate; lets moisture and air pass slowly.
- Membranes: Two thin membranes inside the shell; they separate at the blunt end to form the air cell.
- Air cell: Grows as the egg loses moisture — why older eggs float and peel more easily when hard-boiled.
- Thick white (albumen): Holds the yolk centred; firm in fresh eggs, it thins with age — fresh eggs poach neatly.
- Thin white: Runny outer layer that spreads in the pan.
- Chalazae: Twisted cords anchoring the yolk; perfectly edible, sometimes strained out of custards.
- Yolk: Fat, protein and lecithin — the emulsifier behind mayonnaise and hollandaise.
- Whites begin to set at a lower temperature than yolks, which is why soft-boiled eggs have set whites and runny yolks.
- US food-safety advice: cook eggs until yolk and white are firm, and egg dishes such as frittata or quiche to 160 °F (71 °C).
Sources
- Safe Minimum Internal Temperature Chart for Cooking — FoodSafety.gov (US Department of Health and Human Services)
Chilli: where the heat lives
Capsaicin is made in the pale placenta (ribs) where the seeds attach — not in the seeds themselves.
- Stem and calyx: Cut off and discard.
- Wall (flesh): Flavour and colour; in most chillies relatively little heat, though super-hot varieties also make capsaicinoids in the wall.
- Placenta / ribs: The white tissue down the middle, where capsaicinoids are produced in tiny vesicles — the hottest part.
- Seeds: Pick up heat from contact with the placenta, but do not produce it.
- To tame a chilli, scrape out the white ribs as well as the seeds.
- Heat varies hugely between and within varieties — taste a small piece first.
Herb stems vs leaves
Tender-stemmed herbs can be used stems and all; woody herbs need stripping.
- Tender leaves: Coriander, parsley, dill, basil, mint: add at the end or raw; heat dulls them.
- Tender stems: Coriander and parsley stems are full of flavour — chop finely into pastes, chutneys and bases.
- Woody stems: Rosemary, thyme, oregano: too tough to eat; strip leaves, or add whole sprigs to braises and remove later.
- Roots: Coriander roots are pounded into Thai curry pastes.
- Woody herbs survive long cooking; tender herbs are best added late or raw.
Garlic: head, clove and germ
A head (bulb) is made of cloves, each wrapped in papery skin, with a root end and sometimes a green germ.
- Head / bulb: The whole cluster. Roast whole for a sweet, spreadable paste.
- Clove: One segment; cutting or crushing breaks cells and releases pungent compounds — the finer the cut, the stronger the flavour.
- Skin: Papery layers; loosen by crushing gently under a knife.
- Root end: Hard base; trim it off.
- Germ: The green shoot in older cloves. Many cooks remove it, saying it tastes harsher or bitter — a matter of taste rather than safety.
- Garlic burns quickly — add it after onions, or to warm (not smoking) oil.
Some of this is common kitchen wisdom rather than settled science.
Citrus: zest, pith and segments
The aromatic oils live in the coloured zest; the white pith beneath is bitter.
- Zest (flavedo): Thin coloured outer layer full of aromatic oil glands.
- Pith (albedo): Spongy white layer; bitter in most citrus — avoid when zesting.
- Segment membrane: Thin skins around each segment; cut away for supremes.
- Juice vesicles: The flesh: tiny juice sacs.
- Seeds: Bitter; strain out of juice.
- Zest before you juice — it is impossible afterwards.
- Candied peel uses pith that has been blanched to remove bitterness.
A grain kernel
Whole grains have three parts; refining removes the bran and germ.
- Bran: Fibrous outer layers; slow water absorption — whole grains take longer to cook.
- Germ: The embryo; rich in oil, so whole-grain flours go rancid sooner. Store them cool.
- Endosperm: Starchy centre — what remains in white rice and white flour.
- Husk / hull: Inedible outer layer removed from rice, barley and oats before sale.
- Brown rice needs more water and time than white rice because the bran slows absorption.
Onion: root, layers and grain
An onion is layers of swollen leaves joined at a root plate; its 'grain' runs from root to tip.
- Papery skin: Dry outer leaves; discard (or use for stock colour).
- Layers (fleshy leaves): Each ring is one leaf; they separate into petals.
- Root plate: Holds the layers together — keep it on while dicing.
- Grain: Lines running pole to pole; slicing with them keeps strands intact, across them breaks more cells.
- Stem / neck: Top end; cut off first.
- Leave the root on while dicing so the layers stay together; cut it off last.