How to judge the deterioration of Stinky tofu

After Stinky tofu deteriorates, it will have obvious characteristics such as abnormal smell, texture change, color change, mildew breeding, and sour taste. Deteriorated Stinky tofu may produce a pungent ammonia flavor or a putrid flavor, with a sticky and smooth surface, loose and porous inside or hardened and caked, black and green in color, villous plaques in the mildewed parts, and obvious bitterness or rancidity when tasting.

As a fermented bean product, the deterioration process of Stinky tofu is directly related to the overproduction of microorganisms. The odor produced by normal fermentation is a rich bean aroma mixed with sulfide aroma. After spoilage, sulfides are converted into ammonia substances, producing a pungent odor. In terms of texture, proteins lose their elasticity after being decomposed by spoilage bacteria, resulting in mucus or dry hard layering. The color change is caused by the growth of fungal spores, and common molds such as Penicillium and Mucor can form green or black colonies. The abnormal taste comes from the organic acids and biogenic amines produced by the metabolism of spoilage bacteria, which may cause gastrointestinal symptoms such as nausea and vomiting.

Some commercially packaged Stinky tofu may have swollen bags or turbid juice, but unopened products may also deteriorate due to incomplete sterilization. Home made Stinky tofu is more vulnerable to environmental contamination, especially when stored at 25-30 ℃, the propagation rate of pathogenic bacteria such as Staphylococcus aureus is accelerated. It should be noted that Stinky tofu itself has a fermented sour taste, which should be distinguished from the deteriorated sour taste, which is often accompanied by irritation of the oral mucosa. If network mold or powdery mold spots are found on the tofu embryo, even if it is locally moldy, it should be discarded as a whole.

When purchasing Stinky tofu, you should choose the vacuum packaging products from regular businesses. After opening, you need to refrigerate them and eat them within 48 hours. Self made Stinky tofu needs to use special fermentation bacteria. The fermentation container should be sterilized with boiling water. The fermentation at room temperature should not exceed 36 hours. Soak in clean water for 10 minutes before consumption. If the soaking water becomes turbid or emits an odor, do not consume. People with weak gastrointestinal function and pregnant women should control their food intake, and seek medical attention immediately if symptoms such as abdominal pain and diarrhea occur. When storing, pay attention to separating from fresh food to avoid cross contamination and accelerate spoilage.