Phytochemicals. Protection. Culture. And how spices kill food spoilage bacteria.
Cumin, chillies, garlic, ginger and lemongrass are five of the many spices used in recipes that give dishes like curries their distinctive flavors and aromas. Many of these dishes are an important part of the cultures around the world.
These spices also played a very important historical role in shaping these cultures. Before we invented refrigeration, meat spoiled more readily in hotter climates. At the same time, spices and spicy food can kill food spoilage bacteria. Hence over time, the hotter climates saw more cooking and consumption of spicy foods than in colder climates. (You can read about this intersection of climate, culture, and biology in the 1-Minute NomNom “Too spicy? Keep calm and curry on.”).
How do spices kill bacteria? It has to do with their phytochemicals. Phytochemicals are chemical compounds that are not essential to plant metabolism – hence also called secondary compounds – but give the plant other properties such as color, smell, taste etc.
According to a research paper from Cornell University, these phytochemicals also protected the plant from “herbivorous insects and vertebrates, fungi, pathogens, and parasites”. Plants had evolved these anti-microbial properties to increase their odds of survival against organisms that might infect or even kill them.
When these spices are used in cooking, the phytochemicals are not destroyed because they are thermally stable. They are passed to the dishes that are being cooked. The anti-microbial properties so passed is what helps to kill any food spoiled bacteria there might be in the food. The risks of consuming toxic food is hence reduced.
Food is a big part of any culture around the world. When we dive into the science, it turns out that it comes down to the phytochemicals that are found in plants. Sounds like plant culture has just taken on a whole new meaning!
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