Why red-braised pork (红烧肉) needs to simmer for at least 20 minutes to become tender

[Ho Kwok Leung]

Why red-braised pork (红烧肉) needs to simmer for at least 20 minutes to become tender. I've structured it similarly for clarity:

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### **1. Breakdown of Collagen**
- **Role of connective tissue**: Pork belly (used in红烧肉) contains abundant collagen, particularly in the skin and marbled layers. In raw meat, collagen forms a tough, fibrous structure that makes the meat chewy.
- **Hydrolysis process**: When heated above 60°C (140°F), collagen begins to denature and slowly convert into gelatin. Gelatin is hydrophilic, absorbing moisture and creating a soft, melt-in-the-mouth texture.
- **Time requirement**: This hydrolysis reaction requires sustained heat. While 20 minutes initiates the process, traditional methods often simmer for **1-2 hours** to fully transform collagen.

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### **2. Softening of Muscle Fibers**
- **Myofibrillar protein denaturation**: Initially, heat causes muscle fibers to contract and expel moisture, temporarily toughening the meat. However, prolonged gentle heat (80–100°C / 175–212°F) relaxes the fibers, allowing the meat to reabsorb moisture and soften.
- **Temperature control**: Slow simmering avoids rapid protein coagulation (as in high-heat frying), ensuring even heat distribution and uniform tenderness.

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### **3. Fat Rendering and Flavor Infusion**
- **Fat melting**: The fat layers in pork belly gradually render during simmering, lubricating the lean meat and enhancing its juiciness. This also helps caramelized sauces (soy sauce, sugar, spices) penetrate the meat.
- **Flavor development**: Extended cooking deepens flavors via Maillard reactions and sauce reduction, though tenderness primarily relies on structural changes in the meat.

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### **4. Why Can’t We Shorten the Time?**
- **Pressure cooker vs. traditional simmering**: A pressure cooker (120°C+/248°F+) accelerates collagen breakdown, achieving tenderness in 15–20 minutes. However, traditional slow simmering allows richer flavor integration and even texture.
- **Meat size matters**: Larger chunks require longer cooking for heat to penetrate fully.

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### **Summary**
The tenderness of红烧肉 hinges on collagen→gelatin conversion and muscle fiber relaxation, both requiring time and controlled heat. While 20 minutes is a baseline, 1–2 hours of simmering ensures optimal results. For quicker cooking, use a pressure cooker or smaller cuts, but patience rewards you with deeper flavors and silky texture!