Short Answer:

Yes, adding a small amount of oil to frozen foods before air frying can improve crispiness. The oil helps brown the exterior, enhances flavor, and creates a slightly crunchy texture on the surface.

However, too much oil is unnecessary because air fryers use circulating hot air to cook and crisp food. A light spray is sufficient to boost crispiness without making the food greasy, especially for breaded or coated frozen items like nuggets, fries, or spring rolls.

Detailed Explanation:

Adding Oil for Crispiness

Role of Oil in Air Frying
Oil promotes the Maillard reaction, which is responsible for browning and creating a crispy outer layer. When lightly sprayed on frozen food, oil helps the surface crisp faster while retaining moisture inside, producing a desirable texture. Without oil, some coated or breaded items may not brown as evenly or achieve maximum crunch.

Types of Frozen Foods That Benefit
Breaded items like chicken nuggets, mozzarella sticks, or spring rolls respond well to a light oil spray. Even frozen fries or vegetables can develop a more appealing golden color and slightly crisp edges with minimal oil. High-moisture foods may not need oil, as the circulating hot air is usually enough to crisp the exterior.

Amount of Oil to Use
Only a small amount of oil is needed—usually a light spray or 1–2 teaspoons for a full basket. Excess oil can make the exterior greasy and reduce the crispiness by creating a heavier coating that traps moisture. Use minimal oil to enhance texture without compromising flavor.

Application Tips

• Spray oil evenly over all frozen pieces to ensure uniform browning.
• Toss or shake the food halfway through cooking to distribute oil and heat evenly.
• Combine with proper temperature (180–200°C) and cooking time for optimal results.

Alternative Techniques
Even without oil, frozen foods can become crispy due to the high heat and hot air circulation in the air fryer. Oil simply enhances the effect, especially for foods with breading or coatings that benefit from additional browning.

Additional Benefits

• Improves visual appeal with a golden-brown exterior.
• Enhances flavor by providing a slightly richer taste.
• Helps maintain crispiness for thicker or breaded items.

Conclusion:

Adding a small amount of oil to frozen foods before air frying can improve crispiness, browning, and flavor, particularly for breaded or coated items. Light oil sprays combined with proper temperature, cooking time, and shaking or flipping create golden, crunchy exteriors while keeping the interior moist. Excess oil is unnecessary and may reduce texture quality.