|The old castle town of Aizu lies deep in the mountains several hours north of Tokyo. During the last century, Aizu was the scene of fierce fighting as the last of the samurai daimyos resisted Imperial forces in an attempt to keep their power. Today Aizu is a cultural center known for the quality of its lacquer ware and other fine crafts of old Japan. Here, in this historic town, is the Hiraide family sesame oil shop, one of the last authentic oil pressers.
Tama shibori, or simple pressing, is the traditional process used at the Hiraide shop. Without high temperatures or chemicals, this centuries-old method produces sesame oil with a fresh, nutty taste and aroma, while retaining most of the oil's original healthful qualities.
The Hiraide family begins by selecting golden sesame seeds, the very best available. The seeds are slowly toasted in a unique wood-fired toasting machine. According to Kichisaburo Hiraide, the fifth generation head of the family shop, wood toasting heats the seeds from the inside out. In contrast, says Hiraide, "electric toasting heats from the outside in, which gives typical toasted sesame oil a subtle harshness not found in wood-fired oils."
Next, the toasted seeds are crushed by simple rollers and then lightly steamed for a few minutes. Steaming heats and moistens the seeds, which allows the oil to flow more freely.
The steamed sesame meal is placed in a wooden pressing tub that is lined with two types of filters, one made of paper and the other made of human hair. (The few remaining Japanese oil makers who still use filters made from human hair claim it gives their oil its characteristic "soft texture." The tub of warm sesame meal is then pressed.
With gentle pressure, the crushed sesame seeds easily release their rich, golden oil, which passes through the filter and drips from the bottom of the tub. This first pressing is called ichiban shibori; its warm, nutty aroma fills the old workshop. Filtered once more, this time through hand-made Japanese paper, the oil is bottled immediately without the use of preservatives.
When stored at room temperature and exposed to air and light, most natural vegetable oils gradually turn rancid. Fortunately, a minute amount of sesamol, a natural component of sesame seeds, protects sesame oil from oxidation. This is why sesame oil, of all the edible oils, is the least subject to rancidity and loss of flavor over time.
The simple, but labor-intense methods used by the Hiraide family for over 150 years may seem impractical by modern manufacturing standards. Kichisaburo Hiraide and his son Yuichi produce a modest thirty quarts of oil for a full day's work. In contrast, large oil companies produce thousands of gallons a day with little effort.
However, the high-speed industrial oil-extraction process strips oil of its flavor, aroma, natural color, and nutritional value. To ensure that every last drop of oil is extracted from sesame seeds, commercial manufacturers add hexane, a petroleum-based solvent, to crushed seeds during pressing. The hexane-extracted oil is then neutralized with sodium hydroxide and deodorized by heating to 400° F. Comparing Hiraide's oil with the typical toasted sesame oil found in Oriental food stores, which is usually made using the industrial extraction process, the significance of simple pressing becomes obvious. The commercial product is dark, overpowering, and has a harsh aroma. By contrast, the Hiraide product, available in the United States under the Mitoku label, is light in color and smells and tastes like freshly toasted sesame seeds; it has a distinctive feel, which has been described as "soft and silky." Hiraide toasted sesame oil is more than a delicious, healthful food. In a sense, it is one of Aizu's cultural treasures, a vestige of old Japan.