Do your baked seed crackers lose nutrients? What science says about the heat

Nuts and seeds can contain a potential carcinogen if roasted at high temperatures for long periods. Photo / Getty Images

I bake seeded crackers using chia, pumpkin, flax, sesame and sunflower seeds. Does baking them for 50 minutes at about 180°C cause a loss of the seeds’ goodness?

Answer:

Nuts and seeds are small but mighty: nutritional powerhouses packed with fibre, protein, healthy fats and minerals. Eating
patterns that include nuts and seeds alongside legumes and seafood in place of typical protein sources like red meat are consistently associated with a lower risk of cardiovascular disease, type 2 diabetes and some cancers.

So, your daily cracker habit is on the right track. But what happens to these nutrients when seeds are ground and baked? Let’s start with the good news. Minerals such as iron, magnesium, zinc and calcium are highly stable, so baking won’t destroy them. Likewise, protein, carbohydrate and fibre are all robust under heat and remain intact in your finished cracker.

Where heat does nibble away is in the more delicate nutrients such as vitamin E, a fat-soluble antioxidant, and some B vitamins. These are vulnerable to prolonged heat exposure, which can cause them to degrade, so baking at 180°C for 50 minutes will likely reduce their levels.

The healthy polyunsaturated fats in seeds, especially alpha-linolenic acid in flax and chia seeds, are also somewhat sensitive to oxidation under high heat, though they’re not destroyed outright.

And some antioxidant phytochemicals degrade with time in the oven, although not completely. Essentially, the longer the cooking time and the higher the cooking temperature, the greater the loss of these sensitive nutrients.

Another consideration is acrylamide, the chemical contaminant formed when certain amino acids and sugars undergo browning reactions at high temperatures. Acrylamide is categorised as a potential human carcinogen by the World Health Organisation. Potato crisps, chips, bread and cereals are the biggest dietary sources of acrylamide in a typical New Zealander’s diet, but roasted nuts and seeds can contain acrylamide, too, especially when they’ve been roasted at high temperatures for long periods. Sesame seeds, for example, can develop relatively high concentrations compared with other nuts and seeds, although the actual contribution to your overall acrylamide intake is still far smaller than from potato products.

So, is home baking still a better bet than buying supermarket crackers? Absolutely. You’re using whole, minimally processed ingredients with no unnecessary flavourings, coatings or preservatives, and you can control the amount of added salt to suit your tastes.

Even with some nutrient losses, your crackers remain a rich source of fibre, minerals, healthy fats and protein. And compared with many packaged crackers, they’re probably lower in sodium and free from refined starches.

Here are a few ways you can further tip the scales in your favour:

• Lower the oven temperature: Baking at 150-160°C rather than 180°C helps preserve sensitive vitamins and fats, while also limiting acrylamide formation – a double bonus.

• Shorten the bake time: A thinner cracker or slightly shorter bake (say 25-30 minutes) could also reduce nutrient losses.

• Store smartly: Keep your crackers in an airtight container away from light to prevent the fragile fats from oxidising.

The bottom line? Yes, extended high-heat baking does cause some loss of vitamins and fragile fatty acids and may produce a little acrylamide. But the overall “goodness” of seeds remains. You’re still getting fibre, minerals, protein and healthy fats in abundance – and the satisfaction of a homemade cracker that beats the supermarket version on taste any day.

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