SF Fig. 2.4. (A) Salt evaporation ponds in Ile de Ré, France.
Image courtesy of World Imaging
Title
Traditional Ways of Knowing: Salt Harvesting
NGSS Disciplinary Core Ideas
Table of Contents
Solar Evaporation
SF Fig. 2.4. (B) Salt evaporation ponds near Maras, Peru.
Image courtesy of Pululante
SF Fig. 2.4. (C) Aerial view of evaporation ponds near southern San Francisco Bay, California.
Image courtesy of dr0!d
Traditionally, salt was harvested from either solar evaporation ponds or rock deposits. Salt evaporation ponds are shallow, artificial basins designed to extract salt from seawater, salty lakes, or mineral-rich springs through natural evaporation (SF Fig. 2.4). As the water dries up, the salt crystals are harvested by raking. Salt evaporation ponds are almost entirely located in warm climates with high evaporation and low precipitation (little rain). Today, seawater is sometimes filtered to remove impurities before solar evaporation.
Traditional French Salt Harvesting
There are two types of salt formed by evaporation of seawater and harvested using traditional methods; fleur de sel (flower of salt) and sel gris (grey salt). Although these are French words, they can also refer to salt produced outside of France. Fleur de sel is hand-harvested sea salt that is collected from the top of salt ponds. It is white, crispy, and flaky. It is often used as a “finishing” salt to flavor foods right before eating (SF Fig. 2.5 A). Fleur de sel is not produced in large quantities and is labor-intensive, thus it can be very expensive. Sel gris, in contrast, comes from the same solar evaporation salt ponds as fleur de sel but is produced in greater quantities and harvested differently. Sel gris salt crystals fall to the bottom of the pond before being collected. Sel gris is generally grey, composed of large cube-like course crystals, and has a higher mineral concentration than fleur de sel (SF Fig. 2.5 B).
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SF Fig. 2.5. (A) Fleur de sel (B) Sel gris
Image copyright and source
Image A courtesy of Christian Mertes. Image B by Jordan Wang
Traditional Hawaiian Salt Harvesting
Native Hawaiians used sea salt, pa‘akai (“to solidify the sea”), to season and preserve food, for religious and ceremonial purposes, and as medicine. Preserving food like i‘a (fish) and he‘e (octopus) was essential not just for storage on land, but also to provide nourishment during ocean voyages. In Hawai‘i, sea salt can be collected from rocky shoreline pools, were it occurs as a result of natural solar evaporation. Native Hawaiians also harvested sea salt on a larger scale through the use of man-made shallow clay ponds. One of the few active salt ponds is located on the island of Kaua‘i near Salt Pond Park in the ahupua‘a (watershed) of Hanapepe, where salt is made according to ancient traditions.
In Hanapepe, underground seawater is accessed from deep wells and held in holding pools, where the seawater becomes concentrated through evaporation, and then transferred to shallow ponds (SF Fig. 2.6 A). The amount of time it takes until the salt is ready to be harvested from the shallow ponds depends on environmental factors like precipitation. Salt is not harvested during the winter months when it is rainy. During harvest, the top, white sea salt is raked, rinsed, and dried (SF Fig. 2.6 B). This salt is used like table salt. Some of the white salt is also mixed with red ‘alaea clay, which is collected from the mountains of Waimea (SF Fig. 2.6 C). The red color comes from iron oxide in the clay. Native Hawaiians believe that ‘alaea gives the salt spiritual power; it is used in traditional ceremonies, for ritual blessings and purifying, and for healing purposes.
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SF Fig. 2.6. (A) Salt evaporation ponds in Hanapepe, on the island of Kaua‘i, Hawai‘i.
Image copyright and source
Image by Kanesa Seraphin
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SF Fig. 2.6 (B) Raking the top of the salt ponds in Marakkanam in Tamil Nadu, India.
Image copyright and source
Image courtesy of Sandip Dey from Wikipedia
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SF Fig. 2.6 (C) ‘Alaea salt is a Hawaiian salt made from solar evaporated seawater. The salt is then coated with red clay.
Image copyright and source
Image courtesy of Glane23 from Wikipedia
The middle layer of salt is a pinkish color and also used for seasoning, blessings, and medicine. The bottom layer of salt, which is only harvested once at the end of the season, is brown. It is used as bleach, for pickling, for blessings, and to maintain kalo (taro, a root vegetable) loʻi (fields) and loko iʻa (fish ponds).
Although the Hawaiian salt produced at Hanapepe is harvested using traditional methods, it does not meet strict “food grade” requirements according to the U.S. government. This means the salt may be given as a gift or traded, but it cannot be commercially sold. Because ‘alaea does not meet “food grade” requirements, “‘alaea salt” sold in stores is not made with authentic ‘alaea clay. These requirements are in place to protect the consumer. Interestingly, the cost of manufacturing salt also prevents most “Hawaiian salt” from being produced in Hawai‘i. Here is a Youtube video about the Traditional Saltmaking in Hawai‘i.
Rock Salt
SF Fig. 2.7. Modern rock salt mine in New York
Image courtesy of Pollinator
Salts that are harvested from rock deposits were formed by the evaporation of ancient seas. Rock salt can be mined directly, as shown in SF Fig. 2.7, or acquired by pumping a solvent, like water, into the deposit. Water dissolves the salt, forming a salty brine solution. The salt is then harvested by dehydrating the brine solution. Today, the brine solution may be treated with filtration or chemicals to purify it before dehydration.
Specialty and Seasoned Salts
Unrefined salt contains small amounts of minerals, sediments, and algae that affect the color and taste of the salt. The unique composition of the salt reflects where the salt was harvested. Specialty salts may also be flavored or smoked. Some flavors that have been added to salt include citrus (like lime or lemon), vanilla, celery, truffle, and espresso.
Some salts have become famous for their distinctive color or taste. These are some examples of famous salts:
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SF Fig. 2.8. (A) Himalayan pink salt
Image courtesy of WhosCloset
Himalayan pink salt, a rock salt mined mostly in Pakistan. The pink color is due to iron oxide (SF Fig. 2.8 A).
- Kala namak (“black salt” in Hindi), a rock salt. The salt smells of rotten eggs due to its sulfur content. The dark purple color is due to iron sulphides. The salt begins as Himalayan pink salt that is heated and mixed with Indian spices (SF Fig. 2.8 B).
- Black lava salt, which is made from solar evaporated seawater. The salt is coated with activated charcoal. There is no lava in the salt. The charcoal gives the salt a black color and smoky flavor (SF Fig. 2.8 C).
SF Fig. 2.8. (B) Kala namak
Image courtesy of Sushant savla
SF Fig. 2.8. (C) Black lava salt
Image adapted from Wikipedia
Question Set
- How is most of the table salt in the world produced?
- Research how salt has been harvested in other areas of the world. Where are traditional salt harvesting methods still practiced?
- Research a specialty salt, such as Kosher salt, Maldon salt, or Jukyeom (Korean “bamboo salt”).
- How is the salt made or prepared? For example, is the salt a rock salt or made from solar evaporated seawater?
- What is the shape of the salt?
- Where did the salt originate?
- If the salt is known for a particular flavor, what is the flavor and how is the flavor imparted?
- How do chefs use the salt?
