Short Answer:

To prevent nuts from burning in an air fryer, roast them at a moderate temperature of 160–170°C (320–340°F) and monitor the cooking time carefully, usually 5–10 minutes depending on nut size.

Shake or stir the nuts halfway through roasting to ensure even browning. Using a single layer in the basket and a light coating of oil or seasoning helps create a crunchy texture without burning.

Detailed Explanation:

Moderate Temperature

Burning often happens when nuts are roasted at too high a temperature. Using 160–170°C (320–340°F) allows nuts to cook evenly, releasing natural oils and achieving a golden-brown color without scorching. High temperatures can quickly char the outer layer while leaving the inside raw, creating a bitter taste and unpleasant aroma.

Proper Cooking Time
Cooking time is crucial to prevent burning. Small nuts like peanuts may take 5–7 minutes, while larger nuts like cashews or almonds may need 8–10 minutes. Monitor closely near the end of cooking to avoid over-browning. Remove nuts as soon as they reach the desired color and aroma.

Single Layer Placement
Spread nuts in a single layer in the air fryer basket to allow proper airflow. Overcrowding prevents even roasting and can lead to some nuts burning while others remain undercooked. For larger batches, roast in multiple small batches to ensure uniform cooking.

Shaking or Stirring
Shake or stir the nuts halfway through the cooking process to expose all sides to hot air. This ensures even browning and prevents hotspots that can cause burning. Moving the nuts allows heat to reach every piece, producing a consistent golden color and crisp texture.

Light Oil Coating
A thin layer of oil helps promote even roasting and prevents direct exposure to high heat that can cause burning. Avoid excessive oil, which can lead to greasiness and uneven browning. The oil also helps spices and seasonings stick, enhancing flavor without increasing the risk of burning.

Seasoning Considerations
Add dry seasonings like salt, paprika, or cinnamon before roasting. Avoid wet or sugary coatings during roasting, as they can burn quickly and create a bitter taste. For sweet nuts, add sugar or honey after roasting for the best flavor without burning.

Cooling and Storage
After roasting, allow nuts to cool in a single layer to stop cooking from residual heat. Cooling prevents them from continuing to roast and potentially burning. Store in airtight containers at room temperature to maintain crispness and prevent spoilage.

Conclusion:

Preventing nuts from burning requires moderate temperature, careful timing, single-layer placement, shaking or stirring, and light oil coating. Proper seasoning and cooling help preserve flavor and texture. Following these steps ensures evenly roasted, golden, and crunchy nuts without any burnt pieces.