This study, published in the Journal of Animal Science, investigated the effects of different processing methods on nutrient retention and antioxidant activity in dog foods. The researchers compared four different methods: extrusion, retort, baking, and air-drying. They found that extrusion resulted in the highest nutrient retention, while retort had the lowest. Baking and air-drying fell in between.

The researchers also found that antioxidant activity was highest in extruded and baked foods, and lowest in air-dried and retorted foods. This suggests that the processing method used to make pet food can have a significant impact on its nutritional value and antioxidant content.

Overall, this study highlights the importance of choosing a high-quality pet food that has been made using a careful and effective processing method to ensure optimal nutrient retention and antioxidant activity.

Quoted from: Journal of Animal Science

Freeze-drying techniques were not described in this article. However, it's worth noting that freeze-drying is a relatively gentle processing method that involves removing moisture from the food without the use of heat. This can help to preserve the nutrient content of the food, including vitamins, minerals, and proteins. Additionally, freeze-drying has been shown to retain the natural flavors of the food, which can be appealing to pets.

Overall, with scientific attitude,we cannot provide a direct comparison based on the article of Journal of Animal Science, freeze-drying is generally considered a high-quality processing method for pet food that can help to retain nutrient content and flavor.