14 June 2005

Spicy Foods -- Chemistry is History

What Are Spicy Foods?

Whether you call them spicy, hot, piquant, or pungent, several fiery flavoring agents have been widely used in foods. The "hot" spices include:
  • Pepper (Piper) — black pepper and its relatives, native to India, and members of the plant family Piperaceae

  • Chili (Capsicum) — chili peppers are native to the Americas and are members of the Solanaceae

  • Mustard (Brassica) and its relatives horseradish and wasabi (Brassicaceae). Mustard is native to the Mediterranean region

  • Ginger (Zingiber) and some other members of the Zingiberaceae, of Asian origin
Why do these foods taste "hot"?

They "taste" hot because specific chemicals in the foods bind to receptors in the mucus membranes of the mouth and nose, and also affect those tissues in other ways, creating a complex "trigeminal response", also called "chemesthesis".

Chemical Structures of Some Hot Compounds
(source UMass site)diagrams the chemical structures of piperine capsaicin and zingerone

This page describes the "trigeminal response" in some detail.

This page discusses the structure-function relations
that cause some chemicals to taste "hot", while others do not.

Note that these compounds have hydrophobic structures. They are not very water-soluble. This explains why alcohol or fatty foods are better for washing out hot tastes than water alone.

Why Do We Use Hot Spices?

Whatever the evolutionary or historical reasons for spicing up food, today the principal reason has to be that people like the taste. Migrations of peoples and collision of cultures have brought spicy dishes to every corner of the globe. (You can get Szechwan dishes in Reykjavik or Mexican food in Wellington. I checked.)

Several reasons have been suggested for the widespread use of these spices in earlier times.
  • To cover up off-flavors? They can certainly do this, but there is a downside. If spices merely cover up the smells and tastes caused by spoilage, without affecting the microorganisms that cause them, people would still get sick from eating the spoiled food. However, the ability to consume rotten food in times of scarcity might be useful enough, in spite of the threat of disease. Would this possible benefit be enough to make such spices a traditional part of the everyday diet? I doubt it. Besides, people can eat rotten food if they have to, and even count it a delicacy (e.g. natto). Another point is that spices are expensive — much more expensive than basic foodstuffs. So in times of scarcity could people really afford them?
  • Medicinal qualities? Most spices have been used in various ways by many cultures as elements of traditional medicine. Some of these uses may hint at effects useful in the modern pharmacopoeia. The primary effect noticed so far seems to be antioxidant activity. Antioxidants have many health effects, as well as retarding the oxidation (degradation) of other nutrients in foods.
Also, some spices contain essential vitamins that people need in their diets. Capsicum chili peppers are very high in vitamin C. In fact the elucidation of the chemical identity and structure of vitamin C (ascorbic acid) was made possible by extraction of kilograms of the substance from chili peppers. (Some of the researchers were Hungarians, familiar with paprika. Read about how it happened here, in Albert Szent-Györgyi's Nobel Lecture. See pages 7 and 8 of this PDF file.)
Hot Hot History

Whatever the reason, people all over the world have wanted these spicy spices in their food. This has given such spices enough value to drive key events in human history.

Ironically, Columbus got the Spanish backing for his voyage based on the possibility he might find a competitive route to the East Indies, where spices came from. Pepper was at that time costly in Europe, and the basis of mercantile fortunes in Portugal and, before that, Venice. It could be grown only in tropical climates, and is still today primarily produced in Southern India (where Vasco de Gama landed) and, more recently, Brazil (again showing the Portugese connection).

Of course, Columbus didn't reach the spice lands of the East. But when he arrived in the New World he found something even better -- —chili "peppers". These are much cheaper than true pepper, and can be grown all over the tropical and subtropical world. They have become essential elements of cuisines as disparate as those of Viet Nam, Ethiopia, and Texas.

Further Reading

An interesting article from The Economist

More on History

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1 comment:

Anonymous said...

thanks this realy helped me on my science report.