The same structure, on purpose#

Last week’s structure repeats here: anatomy first, then handling, then portioning.

• beef is the primary material — the animal most students will have handled in the widest range of cuts
• goat and lamb are the same argument applied to a smaller frame with a different fat distribution, not a separate topic

Worked muscle versus resting muscle#

A cut’s texture is a direct record of what the muscle did in the living animal.

• leg, shoulder, neck — worked constantly against load, dense fibre, high collagen (chewy, unrendered)
• loin, along the animal’s back — did comparatively little work, far less connective tissue, finer grain

What follows from that#

• tender with minimal treatment
• dries out rather than softens if treated the way a shoulder is treated
• fat accumulates where the animal stored energy, not where it worked hardest — a related but separate logic from connective tissue

Goat and lamb, briefly#

• proportionally less external fat than beef of a comparable cut
• smaller muscle groups — connective tissue is a larger share of any given cut’s mass

Treatment follows anatomy, not convention#

• high-collagen cut — needs time and moisture for collagen to convert to gelatin
• low-collagen cut — gains nothing from the time a tougher cut requires
• an anatomical answer, even though tradition usually arrives at the same answer by trial rather than by dissection

Unchanged from week 3#

• refrigerate promptly — within 2 hours, 1 hour above 32 °C (90 °F)
• keep at or below 4 °C
• treat any surface or tool that has touched raw meat as contaminated until washed

Portioning#

Along, rather than across, the direction of connective tissue and fibre — this is what makes a portion cook predictably.

The same logic scales with portion size. A primal cut carries the least surface per gram; breaking it down for sale or for the kitchen adds cut surface, and cut surface is where surface bacteria take hold first. Carried to its extreme — grinding — that is why ground red meat keeps for 2 days against the 3–5 days a whole cut keeps (see Whole cuts versus ground, ahead).

Whole cuts versus ground#

Grinding mixes surface bacteria through the whole volume, so ground red meat follows the shorter window rather than the longer whole-cut one.

The danger zone, unchanged#

The 4 °C to 60 °C danger zone applies identically to red meat as to poultry and fish.

Bright red, then brown: oxidation, not spoilage#

A freshly cut surface is bright cherry red; refrigerated, it turns brown. Same pigment, myoglobin, in different chemical states — not different levels of safety.

• oxymyoglobin — myoglobin freshly bound to oxygen, bright red, the colour of a cut just made or a package just opened
• metmyoglobin — the same pigment further oxidised by air and store lighting, brown
• USDA FSIS: this colour shift alone does not mean the meat has spoiled — an intact cut’s interior is often greyish from lack of oxygen, which is normal

What actually indicates spoilage#

Colour records what a surface has been doing chemically since it was cut. It does not, by itself, say whether the meat is still sound. FSIS names three checks that do:

• slime or tackiness on the surface — a texture change, not a colour change
• an off odour — sour or otherwise unlike the neutral smell of fresh meat
• the date on the label, read against how long the meat has actually been held

None of the three is colour. A brown cut with none of them is oxidised; a bright red cut with any one of them is not fresh, whatever its colour says.

Two ground-beef blends, per 100 g#

Raw, from USDA FoodData Central — the same two blends, and the same figures, that this week’s tutorial calculator uses.

Lamb leg and goat, per 100 g#

Same source and convention as the previous slide. Both are whole raw cuts, not ground, and both sit in the calculator as the lower-fat comparison point against the two beef blends.

What the numbers say#

• fat is where the four separate most clearly — from 2.3 g in goat to 17.2 g in the whole lamb leg, a wider spread than the two beef blends show against each other
• iron does not track fat the same way: goat, the leanest of the four, also carries the most iron per 100 g; lamb leg, the fattiest, carries the least
• which cut a recipe should reach for is still the anatomy question covered above, not a question the nutrition table settles