Group 1 - Tofu is a traditional Chinese food with high nutritional value, containing 6% to 12% protein and beneficial plant sterols that help block cholesterol absorption [1] - Tofu varieties include South tofu, North tofu, sour tofu, and lactone tofu, each differing in texture and cooking suitability [1] - Recommended daily consumption of tofu is between 100 grams to 150 grams to avoid digestive issues and increased kidney burden [1] Group 2 - Fresh tofu can be stored at room temperature for up to 7 hours, while factory-packaged tofu should be consumed before the indicated expiration date [2] - Blanching tofu in salt water before refrigeration can extend its shelf life to about two days and enhance its flavor [2] - Tofu that becomes sticky should not be consumed, as it indicates bacterial growth that cannot be eliminated by rinsing [2] Group 3 - Benzoic acid and its sodium salt are commonly used preservatives in the food industry, but their excessive consumption can lead to liver toxicity [3] - The use of artificial coloring agents like lemon yellow in tofu is prohibited, as it can pose health risks if consumed in excess [3] - Aluminum-containing food additives are regulated in tofu production, with a maximum residue limit set to prevent health issues related to long-term exposure [4]