Yes, tofu is considered a fermented food, but the fermentation process involved in tofu production is relatively minimal compared to other fermented foods like yogurt or kimchi. Tofu is made from soy milk through a coagulation process. The coagulation process involves curdling soy milk and separating the curds from the whey. This is typically done using a coagulant, which can be a natural or chemical substance. The most common coagulants used in tofu production are magnesium chloride (nigari) and calcium sulfate (gypsum). While the coagulation process does involve a form of fermentation, it is not as extensive or complex as the fermentation used in other foods. Traditional tofu-making techniques may allow for some degree of bacterial fermentation, but the primary transformation in tofu production is the curdling of soy milk to form curds. Fermented soy products such as tempeh and miso involve more significant bacterial fermentation and are considered more heavily fermented foods compared to tofu.