Phytochemicals. Microbiology. Immunity. And why vegetable self-defence means spicy vegetable recipes are less common.
Spices are plant materials that can kill food spoilage bacteria. They contain chemical compounds called phytochemicals that have anti-microbial properties. These properties are a form of self-defence, increasing the odds of survival against organisms that might infect or even kill them. These same phytochemicals are also what helps to kill food spoiled bacteria, reducing the risks of consuming toxic food (you can read the details in the 1-Minute NomNom “The bacteria didn’t see that cumin“).
This was especially important for meat-based dishes. Before humans invented refrigeration, meat spoiled more readily in hotter climates. One way humans could protect themselves was to consume spicy foods. Hence over time, spicy meat-based foods became more common in the hotter climates than in colder climates (examine this intersection of climate and microbiology in the 1-Minute NomNom “Too spicy? Keep calm and curry on“)
What about vegetable-based dishes? If vegetables and fruits – as plants – already have naturally occurring phytochemicals, humans would not have needed to use as much spice to cook their vegetables as they did for meats. That would mean that spicy vegetable recipes would be less common not only in hotter climates, but in general as well.
That was precisely what the Cornell University scientists who did the above research decided to study. They found that this was indeed true. Their research looked across 36 countries, 41 spices, over 2000 vegetable-only recipes, and 100 plus traditional cookbooks, and discovered that:
- there were fewer spices used per recipe compared to meat dishes
- there were fewer recipes that used more than one spice
- there were fewer recipes that used one “extremely potent anti-microbial spice”
They also found that 38 of the 41 spices were used less often. Spice use in vegetable recipes did increase in the countries with higher temperatures. But it was not to the same extent as what was observed for meat recipes.
The scientists concluded that:
“… because cells of dead plants are better protected physically and chemically against bacteria and fungi than cells of dead animals (whose immune system ceased functioning at death), so fewer spices would be necessary to make vegetables safe for consumption.”
So what is true in spicy meat recipes – that we can keep calm and curry on eating – is even more so for spicy vegetable recipes. In fact, we might not even need to spice things up. Just bring on the kale and carrot on!
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