Freeze-Dried Food: Does It Retain More Active Enzymes and Nutrients Than Extruded Kibble?

## Key Takeaways

Freeze-drying does preserve more heat-sensitive vitamins and certain proteins compared to traditional high-temperature extrusion. However, the often-cited benefit of "active enzymes" is more nuanced—most digestive enzymes in raw ingredients are broken down in the stomach before they can contribute meaningfully to digestion. The real advantages of freeze-dried food lie in nutrient retention, minimal processing, and ingredient integrity. Understanding what freeze-drying actually does (and does not do) helps you make informed choices without falling for exaggerated marketing claims.

## How Freeze-Drying Works

Freeze-drying, also known as lyophilization, is a three-stage process:

1. **Freezing**: The raw ingredients are frozen at very low temperatures (typically below -40°C / -40°F)

2. **Primary drying**: Under vacuum conditions, the frozen water sublimates directly from ice to vapor, bypassing the liquid phase

3. **Secondary drying**: Remaining bound moisture is removed at slightly higher temperatures


The entire process occurs at low temperatures, which is fundamentally different from extrusion.

### How Extrusion Works

Traditional kibble is made through extrusion, where ingredients are mixed into a dough, then pushed through a machine at high temperatures (typically 100°C to 180°C / 212°F to 356°F) and high pressure. The rapid temperature and pressure changes cook the starch, kill pathogens, and create the familiar puffed kibble shape.

## What Does the Science Say About Nutrient Retention?

### Vitamins

Heat-sensitive vitamins like vitamin C, certain B vitamins (especially thiamine/B1), and vitamin E degrade significantly at high temperatures. Studies consistently show that freeze-drying preserves these vitamins at higher levels than thermal processing methods.

- Vitamin C retention in freeze-dried foods can exceed 90%, while high-heat processing may reduce it by 50% or more

- Thiamine (B1) is particularly heat-sensitive and is better preserved through freeze-drying

- Fat-soluble vitamins (A, D, E, K) are moderately affected by heat but also by oxidation during storage


### Proteins and Amino Acids

High temperatures can denature proteins, altering their structure. While denaturation does not necessarily destroy nutritional value (cooking meat still provides protein), it can affect digestibility and bioavailability in some cases. Freeze-drying maintains proteins closer to their natural state.

### The Enzyme Question

This is where marketing often outpaces science. Here is what we actually know:

- Raw foods do contain naturally occurring enzymes (like proteases, lipases, and amylases)

- These enzymes are largely deactivated by the acidic environment of the stomach (pH 1-2) before they reach the small intestine where nutrient absorption occurs

- Dogs and cats produce their own digestive enzymes; they do not rely on enzymes from food to digest their meals

- Some enzymes may survive freeze-drying, but their functional contribution to digestion in pets remains unproven


**The bottom line**: While freeze-drying may preserve some enzyme activity, the claim that these enzymes significantly improve digestion lacks robust scientific support in companion animals.

## Real Advantages of Freeze-Dried Food

Rather than focusing on enzyme claims, consider these evidence-based benefits:

- **Higher nutrient density**: With moisture removed, freeze-dried food packs more protein and fat per gram

- **Minimal thermal damage**: Better preservation of heat-sensitive vitamins and delicate nutrients

- **Ingredient integrity**: Whole meat pieces remain recognizable; you can see what you are feeding

- **Long shelf life without preservatives**: Low moisture content naturally inhibits bacterial growth

- **Convenience**: Lightweight, easy to store, and can be rehydrated or fed dry


## Practical Considerations

### Cost

Freeze-dried food is significantly more expensive than kibble due to the energy-intensive process and higher-quality ingredients typically used. For many pet owners, using freeze-dried as a topper or rotational option rather than a sole diet offers a balance between benefits and budget.

### Food Safety

While freeze-drying preserves nutrients, it does not reliably kill all pathogens the way high-temperature cooking does. Some freeze-dried raw foods may still carry bacteria like Salmonella or Listeria. Reputable brands conduct pathogen testing, but immunocompromised pets or households may need to consider this factor.

### Complete and Balanced Formulation

Not all freeze-dried products are formulated as complete diets. Check whether the product meets AAFCO or FEDIAF standards for complete and balanced nutrition, or whether it is intended as a topper or treat.

## How to Evaluate Freeze-Dried Products

- Look for transparency about sourcing and processing methods

- Check for third-party testing or batch-specific quality reports

- Verify the product is labeled as "complete and balanced" if using as a primary diet

- Consider your pet's specific health needs and consult your vet if they have a compromised immune system


## A Gentle Reminder

If your pet has a sensitive stomach, is immunocompromised, or is transitioning from a very different diet, introduce freeze-dried food gradually and monitor their response. While freeze-dried diets work wonderfully for many pets, individual tolerance varies. When in doubt, consult your veterinarian for personalized guidance.

The takeaway is this: freeze-dried food does offer genuine nutritional advantages over high-temperature processed kibble, particularly in vitamin retention and ingredient quality. But be cautious about exaggerated enzyme claims—the real value lies in what the science actually supports, not in marketing narratives.