If you've ever stood in the baby food aisle squeezing pouches and squinting at labels, you'll know the feeling: everything says it's natural, wholesome, and packed with goodness. But here's the thing most labels don't tell you: how that food was preserved has a huge impact on what actually survives by the time it reaches your toddler's spoon.

Most shelf-stable pouches on supermarket shelves rely on a process called retort processing. It's effective, it's widely used, and it does keep food safe but it relies on intense heat, and heat changes food in ways that matter for taste, texture, and nutrition. Let's break down exactly what happens during retort processing, and why we chose a gentler method instead.

What is retort processing?

Retort is essentially a sealed, high-heat sterilisation process. The food is prepared, sealed into its final pouch, and then heated to 116–121°C for several minutes under high pressure.

This process happens in three stages. First, the retort machine heats up to reach that target temperature and pressure. Second, it holds the food at that temperature for long enough to guarantee the heat has fully penetrated the pouch and killed off any harmful microorganisms, including the bacteria responsible for botulism. Third, it cools the pouch back down under controlled conditions.

That middle stage is the part that does the most damage. The longer food sits at high heat, the more its proteins, starches, and vitamins break down. Manufacturers can shorten this stage with techniques like variable temperature profiles, but some degree of prolonged heat exposure is unavoidable if the food needs to be sterile enough to sit on a shelf for months without refrigeration.

How heat affects taste

Heat doesn't just cook food at the temperatures and durations used in retort processing, it actively breaks down the compounds responsible for flavour. Savoury depth comes from a delicate combination of amino acids, natural sugars, and aromatic compounds in vegetables, herbs, and proteins, many of which are heat-sensitive and degrade or transform under sustained high temperatures.

Prolonged heat exposure can also encourage the formation of off-flavour compounds as raw materials break down at a molecular level part of why some heavily processed savoury foods can taste slightly flat, or develop a faintly "cooked" or tinny note that wasn't there in the fresh ingredients. The result is a final product where the dominant flavour often isn't the vegetable, herb, or protein you'd expect from the ingredients list, but something blander and more generic.

How heat affects texture

Texture suffers for mechanical reasons, not just culinary ones. The combination of intense heat and pressure during retort processing breaks down the cell walls and starch structures that give food its bite and shape. Starches in particular are vulnerable, some break down during processing into thin, watery sauces, which is why many retort manufacturers rely on specially modified starches purely to hold a sauce together through the heat cycle. Proteins react differently depending on the cut or type, with some becoming fibrous or rubbery and others turning unappealingly soft.

The end result is the familiar uniform, slightly gluey consistency you get from squeezing a pouch; a texture that's smooth because the food's original structure has essentially collapsed under heat, not because it was designed that way. Distinct pieces of vegetable, pasta, or protein rarely survive the process intact; everything tends to merge into the same consistency, regardless of what's actually in the pouch.

How heat affects nutritional quality

This is where the impact of retort processing is most measurable. Heat is particularly hard on water-soluble vitamins (vitamin C and the B-group vitamins) which are among the most fragile nutrients in food. Typical retort processing can reduce vitamin C and thiamin content by around 20–40%, with riboflavin losses of 75–85% reported in some studies. Even with modern process improvements designed to minimise heat exposure, updated retort methods are estimated to retain only around 80–85% of nutrients such as vitamin C and certain carotenoids.

Fat-soluble vitamins (A, D, E, and K) tend to fare somewhat better, generally showing 80–90% retention, while proteins, fats, and most minerals remain largely intact. But for the most heat-sensitive nutrients, exactly the ones growing toddlers need consistently, retort processing means a meaningful share is lost before the food ever reaches the spoon.

Why we use freeze drying instead

Freeze drying takes a completely different route to the same shelf-stable result, and it's the method we use for every meal at More Toddler Meals.

Rather than sealing food in its packaging and blasting it with heat, we first prepare and cook each meal gently, the way you would at home. Once cooked, the meal is frozen at extremely low temperatures. It's then placed into a vacuum chamber and gently dried where the ice converts directly into vapour without ever passing through a liquid stage: a process called sublimation. No prolonged high heat. No pressure cooking inside a sealed pouch. Just cold, gentle heat vacuum, and time, doing the job that high heat usually does, far more gently.

That gentleness is the whole point, and it shows up in all three areas retort struggles with:

• Taste — because the food isn't subjected to sustained high heat after cooking, the genuine flavour of the vegetables, herbs, and proteins stays intact. When you reconstitute a freeze-dried meal with water, what you're tasting is much closer to the meal as it was actually cooked.
• Texture — freeze drying preserves the original cell structure of food far better than heat-based methods, since there's no prolonged heat or pressure to break it down. That's why our meals still have distinct, visible pieces of pasta, vegetable, and protein you can see and feel, rather than a single smooth, uniform consistency.
• Nutrition — because the process relies on cold and vacuum rather than heat, freeze drying typically retains 90–97% of most nutrients, especially vitamins, minerals, and antioxidants. Minerals like calcium, magnesium, iron, and zinc remain at nearly identical levels to the fresh ingredients, and even vitamin C - the nutrient most commonly used to benchmark processing damage - holds up dramatically better than it does through heat-based methods.

None of this is about guilt over reaching for convenient food - every parent needs it sometimes, and that's completely normal. It's simply about understanding why one shelf-stable method might serve your toddler better than another, so you can choose with a bit more information behind you. That's the whole idea behind freeze drying our meals: real food, cooked properly, then preserved gently so what reaches your toddler's bowl is as close as possible to what we'd serve at our own kitchen table.

Curious how our freeze-drying process works in more detail? Take a look at Why Freeze Dried to see exactly how we lock in flavour, texture, and nutrition — without the heat.