The substrate for the fermentation is a carbohydrate, usually molasses or a sugar, such as raw beet, refined beet, or cane sugars, or a syrup. … Certain inorganic nutrients, such as ammonium nitrate, potassium phosphate, magnesium sulfate, zinc sulfate, and potassium ferrocyanide, are added. The pH is adjusted to between 3 and 7, depending on the carbohydrate source. Sterilization may be batchwise or continuous; the latter uses less energy and is usually faster. After sterilization, the temperature is adjusted as required. The surface of the sterile substrate in the pans is inoculated with A. niger spores, which germinate and cover the surface of the liquid with a mat of mold. After two to three days the surface is completely covered and citric acid production begins, continuing at almost a constant rate until 80-90% of the sugar is consumed.

https://pubchem.ncbi.nlm.nih.gov/compound/citric_acid#section=Methods-of-Manufacturing&fullscreen=true

https://en.wikipedia.org/wiki/Aspergillus_niger

Edit: I’m going to add the wikipedia page for citric acid since someone pointed out that I was confusing the two.

Citric acid occurs in a variety of fruits and vegetables, most notably citrus fruits. Lemons and limes have particularly high concentrations of the acid; it can constitute as much as 8% of the dry weight of these fruits (about 47 g/L in the juices[11]).[a] The concentrations of citric acid in citrus fruits range from 0.005 mol/L for oranges and grapefruits to 0.30 mol/L in lemons and limes; these values vary within species depending upon the cultivar and the circumstances under which the fruit was grown. Source

  • Dr. Bob@lemmy.caEnglish
    24·
    7 months ago

    The black mold people are concerned about in buildings is stachybotrys. They type species is stachybotrys atrum. Totally different mold.

    • PeleSpirit@lemmy.worldOPEnglish
      46·
      7 months ago

      Still not great:

      OTA, a clinically relevant mycotoxin, can accumulate in human tissue and cause a variety of serious health conditions.[43] Potential consequences of OTA poisoning include kidney damage, kidney failure and cancer but the United States Food and Drug Administration (FDA) has not set maximum permissible levels of OTA in food unlike the EU that set maximum permissible levels in a variety of food products

      • Dr. Bob@lemmy.caEnglish
        31·
        7 months ago

        I take a lot of that mold work with a figurative grain of salt. I’ll confess I’m not familiar with the aspergillus literature, but stachybotrys risks are way overblown. The concerns are driven by courts rather than the medical literature.

        The last time I had a deep dive into it there was a single case of stachybotrys poisoning which occurred when a farmhand fell into a silo of moldy hay. He had a complete recovery within 10 days. That was deep dive was 15 years ago so maybe something else has come up?

        All of these molds are present in the environment. If you spend any time hiking in the woods or around hay or barns you are exposed to reasonably high levels.