Cut & Cooking Presets
Cut Type
Target Core Temp:
135°F (57.2°C) - Medium Rare
Thickness:
32 mm
Post-Cook Resting:
3 Minutes Carryover
Diner Vulnerability Profile
Standard Healthy Adult
Pregnancy / High-Risk
Host Biology: Sheep vs Cattle
Why the difference? Felines shed microscopic Toxoplasma gondii oocysts onto pasture grasses. Grazing sheep ingest these, forming dormant, viable bradyzoite tissue cysts deep within skeletal muscle fibers. Cattle mount an innate immune response that normally eliminates the parasite before encystment.
| Characteristic | Pasture Sheep (Lamb) | Feedlot / Pasture Beef |
|---|---|---|
| Primary Hazard | Deep Intramuscular Cysts (Toxoplasma) | Surface Exterior Bacteria (E. coli, Salm.) |
| Sear Safety | Inadequate if core <145°F | Generally safe (surface seared) |
| Freeze Curing | Devitalizes bradyzoites (≤-4°F) | Does NOT kill bacteria (only pauses) |
Thermal Conduction & Pathogen Distribution
Medium Rare
Exterior Sear Crust (>280°F)
Intermediate Zone
Core Center Temp
Inactivated / Devitalized
Viable Active Pathogen
High Toxoplasmosis Risk for Pregnancy
Core temp of 135°F leaves viable Toxoplasma tissue cysts intact in sheep muscle. Congenital toxoplasmosis risk to fetus.
Effective Peak Temp
138.2°F
+3.2°F carryover rest
Toxoplasma Inactivation
< 1.0 Log
Viable cysts present
Surface Bacteria Kill
> 7.0 Log
Surface pasteurized
USDA FSIS Rule
NON-COMPLIANT
Target: 145°F + 3m rest
Biophysical Lethality & Thermal Physics (D-value Kinetics)
Toxoplasma gondii tissue cysts have a reported decimal reduction time (D-value) of ~9.9 minutes at 131°F (55°C), dropping sharply to ~0.4 minutes at 145°F (63°C) with a thermal resistance constant (z-value) of ~9.5°F (5.3°C). Instant surface searing delivers high lethality to surface E. coli but requires thermal diffusion time to conduct heat inward to the cold center.
Thermal Diffusion Time to Core:
~14.5 minutes
Pre-Freezing Devitalization Credit:
None (Never Frozen)
Ground Meat Cross-Contamination:
Not Applicable (Whole Cut)