Sushi Roll

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Sushi Roll

Background

A sushi roll is a food of Asian origin that features rice and seafood wrapped in seaweed (nori). Until the end of the twentieth century, sushi rolls were only available in restaurants. Today, a number of companies prepare them for retail sale in grocery stores. Although a few of these companies use mechanical sushi makers—called robots—to shape the rice and add condiments, the finest quality sushi rolls are still handmade. An expert sushi chef, a shokunin, can roll and cut six to eight sushi rolls in a matter of moments. It is not the desire for faster production that has led some companies to use the sushi robots; rather it is a shortage of accomplished chefs.

Sushi-making is a time-honored tradition in Japan. This craft is a matter of intense national pride, and it is often noted that the red of the fish and the white of the rice symbolize the red and white of the Japanese flag. This tradition also extends to the types of utensils used. Although some substitutions are acceptable, in the traditional Japanese kitchen the following utensils would be found: hangiri, a small tub made of cypress bound with copper hoops and used for cooling vinegared rice; shamoji, a flat, wooden, rounded spatula used to turn and spread sushi rice; uchiwa, a hand-held fan made of bamboo and covered with paper or silk used to remove moisture from sushi rice; and makisu, mat constructed of thin bamboo strips woven together with string used for rolling sushi.

History

As early as 500 b.c., people living in the mountains of southeast Asia wrapped fish in rice as a means of pickling and fermenting. In Japan, alternating layers of carp and rice were placed in a covered jar and left for up to a year. During this time, the fermenting rice produced lactic acid, thus pickling the fish. When the jar was opened, the carp was eaten, but the rice was discarded.

A Japanese legend holds that a kindly husband and wife placed rice in an osprey nest. When they later checked on the bird, they found a fish nestled in the rice, which they took as a token of the bird's appreciation. As they ate the thank-you gift, they noted that the fermented rice had imparted a distinctive taste to the fish.

In the seventeenth century, the people of culinary-rich Edo (now Tokyo) began the practice of adding vinegar to the rice so that it would ferment in just a few days. Before long, sushi shops were popular sites on the streets of Tokyo. One of the earliest, Sas Maki Kenukesushi, opened in 1702 and was still in business at the turn of the twentieth century.

Although the Japanese have eaten seaweed, or nori, since the eighth century, it was not until the late seventeenth century that it was regularly cultivated in inlets and estuaries up and down that nation's coasts. The nori was harvested in December and January when it had reached its maturity. It was not an easy task because the nori disappeared during the summer months.

In the 1940s, a British scientist named Kathleen Drew-Baker began to investigate what happened to nori spores in the summer. Drew's studies were published in a paper in 1949, which concluded that nori spores burrow into the pores and crevices of seashells, where they grow into pink thread-like organisms. When the weather turns cold, the organisms detach themselves and then adhere to other surfaces where they grow to maturity.

After Drew's conclusions were published, the Japanese quickly developed a cultivating system and nori production increased ten-fold from 1950 to 1980. In 1963, nori farmers erected a bronze statue in Drew's honor overlooking the Bay of Shimbara. On April 14 of every year, a ceremony is enacted in which Drew's cap and gown are placed on the statue, a Union Jack is raised, and farmers placed a tribute of nori from the current crop at the statue's feet.

Raw Materials

Today the cultivation of nori is a very prosperous industry in Japan. Miles of bamboo nets are submerged in inlets on the Japanese coast to provide a growth field for the nori spores. At the end of the growing season in early April, the healthiest spores are selected from the nets and transported to Prefectorial Seeding Centers. There, they are mixed with a liquid suspension and sprayed onto clean oyster shells. It takes 1.5 tons of porphyra seeds to fill 20,000 shells.

The shells are suspended from ropes draped over bamboo sticks over large tanks of water that are held at 50-60°F (10-15°C). The walls and roof of the seeding centers are lined with curtained windows so that the heat intensity can be monitored. The seeds are left to germinate throughout the summer and early fall. The plants are harvested, washed with sea water, then with fresh water. They are then dried into sheets.

Although variety of seafood is used in sushi rolls, including shrimp (ebi), crab (kani), and salmon (sake), tuna (maguro) is by far the most popular. The bluefin tuna market is very competitive. Tokyo's Tsukiji market sets the market price and the day's catch is auctioned to the highest bidder. Prospective buyers extract small samples from the flesh of the fish to test for color and fat content. In order to be considered for sushi, the tuna must meet "kata" or ideal form requirements pertaining to color, texture, fat content, and body shape.

While Japan remains the center for tuna fishing, it is a also major industry in the North Atlantic and in the Mediterranean Sea. However, Japanese techniques are so highly revered that experts from that country are often recruited to advise on matters of catching, handling, and packing. Special Japanese paper is used for wrapping the fish before it is placed on ice. The fish is shipped whole to Japan to be sliced and trimmed. It is not unusual for a tuna to be caught in New England, shipped to Japan for processing, and then shipped back to a restaurant in Boston.

The vinegar used in sushi and sushi rolls is made from fermented rice. It is then poured sparingly into the rice to be used in the sushi roll.

Wasabi, also known as Chinese horseradish, is a common ingredient in sushi rolls. Difficult to cultivate, it grows best on the northern sides of shaded mountain valleys near cold running streams. Wasabi can take two to three years for the edible roots to mature. It is prepared fresh, powdered, and/or as a paste.

Soy sauce is made from fermented soybeans, toasted wheat, barley, salt, and water. It may be purchased from an outside supplier, or processed at the same plant that produces the sushi rolls.

Fresh ginger root is one of the most common spices used with the preparation of sushi rolls. It can also be purchased from an outside source or cultivated in-house.

Vegetable ingredients are as varied as the seafood, but can include cucumber, avocado, and spinach. The vegetables can be purchased from outside vendors.

The Manufacturing
Process

A half sheet of nori is spread onto the makisu. About 0.25 in (6 mm) of vinegared rice is spread onto the nori. A groove is made down the center of the rice with the shamoji.
Strips of seafood and/or vegetables are laid into the groove. Wasabi is distributed evenly on top the seafood and/or vegetables.
The makisu is used to roll the nori around the rice and other ingredients. After rolling, it is pressed manually into a square shape.
The sushi roll is removed from the makisu and sliced into 1.5-in (3.8-cm) pieces.
The shokunin places the finished sushi rolls on small, wooden tables. Fresh slices of ginger are usually also placed on the table along with a side of wasabi. If the sushi is to be shipped to grocery stores, factory workers manually place the sushi rolls in plastic cartons, usually in groups of six or eight. Packets of soy sauce are added. Plastic covers are attached to the cartons and labels are affixed. The cartons are loaded onto refrigerated trucks and shipped immediately to grocery stores.

Quality Control

As with any foodstuff, ensuring the health of the consumer is of utmost concern. Sushi raises particular concerns because of the existence of parasites in raw fish. The Centers for Disease Control in Atlanta, Georgia, and the United States Food and Drug Administration (FDA) both recommend that raw fish be flash frozen at −4°F (−20°C) for three to five days to kill parasitic worms. This process of flash freezing the fish usually takes place at sea. At the wholesalers, the frozen fish is sliced into small, rectangular sections and wrapped in plastic. Still rock hard, the sliced fish is then shipped to the factory.

In Japanese sushi bars (both in Japan and in the United States) raw fish is the norm. These restaurants contract to have fresh fish flown in from around the world. In Japan, the Ministry of Agriculture, Forestry & Fishers (MAFF) administers a voluntary product quality and labeling mark called the Japanese Agriculture Standard (JAS). Over 300 JAS standards exist for agri-food imports. The Japanese government's regulations are particularly restrictive on imports of sushi and rice. The use of American rice in Japanese cuisine is strictly forbidden.

Nori used by the food processing industry is often roasted rather than dried. At the processing plant, the nori is tested for the presence of heavy metals, herbicides, pesticides, Escherichia coli (E. coli), yeast, and molds.

Byproducts/Waste

Although much of the waste material from fish processing is returned to the sea, a lucrative fish byproduct industry exists. In the United States alone, this amounts to 2 million pounds annually. Organs, bones, and scales are used to make fish meal and bait. Bones are also used to produce fish stock and soups. Fish skins are used in the production of some leather products. The medical community uses fish oil to produce food supplements.

The Future

The popularity of sushi is expected to continue to grow in the twenty-first century. The challenge will be keeping up with the demand. Tuna is especially in danger of being over-fished. At the end of the twentieth century, some American restaurants were refusing to serve tuna in an effort to end the depletion of the species.

The International Commission for the Conservation of Atlantic Tuna (ICCAT), based in Madrid, is responsible for assigning quotas for bluefin tuna in the North Atlantic and in the Mediterranean Sea. However it is difficult to regulate a fish that can swim up to 50 miles per hour (80 km/hr) across multiple jurisdictions. The result is that ICCAT and various wildlife agencies, including the United States National Academy of Sciences and the National Audubon Society, disagree on exactly how many bluefin tuna migrate over the North Atlantic.

The proliferation of salmon farming is also causing controversy. Farmed salmon are fed a diet of dead fish and are often treated with anti-bacterial chemicals. In addition, coloring agents are added to food pellets to give the salmon the pink tint that would normally be gotten from eating krill and shrimp in the wild. Opponents argue that the waste material that is discharged as a result constitutes a serious environmental hazard. An outbreak of Infectious Salmon Anemia in 1998 in Scotland has also been blamed on poor conditions in the fish farming industry.