Tauco or taotjo is simply an Indonesian style of fermented yellow soybean paste and is used in many Chinese-Indonesian and Sundanese cuisines.
Tauco was brought to Indonesia by Chinese Immigrants. Based on their knowledge of making douchi or tausi, made of black soybean, they created the alternate one by using yellow soybean to fulfill the longing of their home country delicacy. The process is mainly fermenting and salting, which are a useful process for creating Tauco characteristic flavor.
If you can’t imagine or just have no idea what tauco tastes or looks like, try to imagine Japanese well-known Miso. Yes, that Japanese Miso Soup or Miso Ramen!
The difference between Miso and Tauco is not only from its origin country, although they have similar main ingredients which are soybean and salt. Aside from them, miso is also made by fermenting barley and special microbe culture called Kojikin, which contains Aspergillus oryzae mold ( used for making soy sauce and sake). In the beginning, you might think that both Tauco and Miso seem unappetizing, unattractive and it has unpleasant smell almost like rotten fish, but without them, your dishes will not be that tasty! Why? As the result of this fermentation with mold, they will produce glutamic acid, which can provide umami  flavor. Glutamic acid is the main amino acid found in MSG (Monosodium Glutamate) or known as vetsin or micin. So when MSG itself is still a subject of controversy, although it is used as flavor enhancer especially in Chinese foods, that give birth to a syndrome called Chinese foods syndrome , why not using local ingredients as flavor enhancer such as tauco.
Making tauco is basically almost the same as making tempeh, the different is in the addition of salt and final process. First, sort the soybean and remove the defect soybean since we want to have high-quality
First, sort the soybean and remove the defect soybean since we want to have high-quality tauco, soak for a night and after soaking, filter it from water to be boiled later. After boiling process, the soybean is cooled down and added with starter mold culture and rice flour or/and tapioca flour or/and wheat flour. The starter mold culture usually consisted of Aspergillus oryzae, Rhizopus oryzae, and Rhizopus oligosporus.
The result of them working hard in 2-5 days fermentation is not only the delicious characteristic flavor from breakdown of protein and carbohydrate, but unfortunately since they are overexcited and too full of themselves so they also produce ammonia and bitter flavor from the protein breakdown on the softened soybean. Ammonia is the smelly substance you can find in urine or spoiled meat. So to stop these super happy molds, we will add brine solution (18-20%) for the salting process which unfortunately will kill them because they won’t stop eating and working, along with some uninvited bacteria that might be dangerous to your body.
Brine solution which can be made by dissolving salt in water is antimicrobial substance, but there are also some bacteria which will not be killed by salt, such as lactic acid bacteria and yeast, for example, Lactobacillus, Pediococucus, Hansenula, and Zygosaccharomyces. These guys are pretty useful because aside from eating the main protein and carbohydrate course, they also produce lactic acid, other organic acids and alcohol that can reduce salty taste of tauco and producecharacteristic flavor components, such as glutamic acid from protein.
After 2-4 weeks, the tauco is sundried for another 2-4 weeks for concentrating process until the color is reddish brown. The reddish brown color is the result of Maillard reaction between the amino acid and the sugar reduction in Tauco. Tauco is then cooked with palm sugar. After the cooking process, tauco is grounded to be paste-like texture and then sometimes added with soybean oil to make it easier to be spooned before packed into a bottle or jar.
There are two types of tauco, moist and slurry-like tauco and dry tauco. The moist tauco is packed after cooking process with palm sugar without sun drying while dry tauco is made by drying the moist tauco. The unique thing about Tauco is that the different place they are made, the different also the flavor. It’s because most of Tauco maker usually don’t use starter culture, but using spontaneous fermentation method, so it’s basically the microorganism from air will occupy the soybean for fermentation and also some tauco-makers preferred to have sweeter or saltier tauco. Different places also mean different microorganism in the air.
Tauco is usually made traditionally in several cities, such as Bangka, Cianjur, and Medan, although Cianjur is the biggest producer of tauco.
1. When you buy tauco, choose the one with light brown, brown color and smell tauco characteristic aroma. Don’t forget also to check the expired date!
2. Keep tauco in an airtight container and refrigerate after usage.
3. When cooking a dish, add tauco in the beginning before other spices. It should make your food tastier!
References: Umami is a Japanese word that can be translated as pleasant savory or meaty taste and is one of the five basic tastes together with sweet, sour, bitter, and salty. It can be tasted in cheese, soy sauce and many other fermented and aged foods, this taste also present in tomatoes, grains, and beans.
 Chinese foods syndrome is unpleasant sensation after eating Chinese food, it is actually a nuisance for your body in forms of headache, rapid heart rate and numbing, possibly due to body sensitivity to MSG.