Sato or nam-khao is a kind of alcoholic spirit made from various kinds of rice fermented using a small ball of mold or yeast so that the rice breaks down into alcohol. Fully fermented sato can have an alcohol content of up to 15%.
Sato is classified as a rice wine,aundistilled kind of alcoholic beverage popular in Asian countries such as China, Korea, Japan, and Thailand though named differently in each country. For example, in China, the wine is called chao-chin-yu; in Japan, it is called sake. As for Thailand, wine of this type has numerous names according to the production process used, such as krachae, lao-argoon, and nam-khao. The most popular and most well known kind seen nowadays in Thailand is sato.
Sato has a sweet flavor because the fermentation is not allowed to finish, and thusit has a relatively short shelf life, although some places ferment it until it is clear with only some sediment. At that point it is alcoholic enough that it can be stored longer or distilled into lao-khao, (rice whiskey, a hard liquor).
Sato can be either clear or murky depending on the production process and the desires of the consumer. Regardless, new forms of sato can be developed by adjusting the aroma and flavor, for example by using herb infused water or some types of fruit juice during the fermentation step. This leaves behind the flavor of the herb or juice and thus creating a novel variety of satofor consumers to choose from.
Sato is different from fruit wines in that it has a significant amount of rice fragments and sediment to the point of turning the wine a cloudy white colorThe production process also creates a great deal of sugar, which can feed microorganisms and in turn cause spoilage. Therefore it is necessary to filter out the sediment. Generally it is left to rest for some time in order for the sediment to settle on its own. Sato in this way can be kept for some time without adding preservatives.
The process of sato production:
Fermentation of sato uses rice as its primary ingredient and is processed as follows:
1. The rice must be washed to cleanse it of foreign particles to help reduce the chance of contamination from microorganisms. The water used to wash and soak the rice, as well as that used during fermentation, must therefore be high quality, clean, and potable. As for soaking the rice, the goal is to absorb 25-30% of its mass in water before steaming it. The water will permeate through the endosperm over the course of about 3 to 4 hours.
2. After washing, the rice is steamed so that the starches turn to gelatin (gelatinization) and the proteins break down (protein denaturation) so that the yeast enzymes more easily metabolize the rice. Steaming takes 30-60 minutes. After steaming, the rice is cooled. In order to adjust the water content of the rice, it is sprinkled with clean water until it is 45-55% water before adding the yeast.
3. Once ready, the rice is fermented with starter yeast, which is often pinched off from a small yeast ball. The process of fermentation begins with combining the rice and yeast in the fermentation tank. In the first 2-3 days of yeast growth, the fermentation creates the amylase enzyme in order to break the starch down into sugar (a process called saccharification), which results in a sweet liquid called nam-toy. The highest level of sweetness attained is between 37-47 brix (depending on the type of rice). After this,high quality, sterilized water is added in order to attenuate the sweetness and adjust the brix level to between 20-22 brix. During the latter part of fermentation, the yeast changes the sugar into alcohol and carbon dioxide and the fermentation process can continue for another 4 to 7 days or until the level of alcohol reaches 10-12%.
4. At this point the fermentation is halted andthe sato, without the yeast, is poured from the fermentation tank into another tankcontaining chemicals which kill the microorganisms and deactivate them.
Since long ago,sato has been passed down through history by Thailand’s ancestors. Sato can be considered the original Thai rice wine. Even though currently the consumption ofsato is hardly seen often, in rural areassato is still made to drink during festivals or special events. If you have the opportunity to get your hands on some sato, don’t miss the chance to try the unique flavor of Thai’s original rice wine.