Calcium propionate's anti-mold and anti-corrosion effects are affected by a variety of factors, as follows:

Environmental pH value: Calcium propionate can play a better role in mold prevention and anticorrosion only in an acidic environment. Because its anticorrosive effect mainly relies on propionic acid, under acidic conditions, calcium propionate will dissociate propionic acid, and propionic acid molecules have the ability to inhibit the growth of microorganisms. When the pH value of the environment increases, the degree of dissociation of propionic acid decreases, and the undissociated propionic acid molecules decrease, so the effect of antimicrobial and anticorrosive will be weakened. Generally speaking, calcium propionate is more effective in the environment with pH value of 5 - 6.

Concentration: Normally, the higher the concentration of calcium propionate, the better the effect of antimold and anticorrosion. However, too high a concentration may bring some negative effects, such as affecting the taste of the product, odor or other adverse effects. Different application scenarios and products have different requirements on the appropriate concentration of calcium propionate, for example, in bread making, the general adding amount of 0.1% - 0.3% can play a better effect of mold prevention.

Temperature: Temperature has a certain effect on the antimold and anticorrosion effect of calcium propionate. On the one hand, the temperature affects the growth and reproduction rate of microorganisms, at a lower temperature, the growth of microorganisms is slow, and the effect of calcium propionate is relatively easier to play; on the other hand, the temperature also affects the dissociation and diffusion speed of calcium propionate. Generally speaking, within a certain temperature range (e.g. 20 - 30℃), the effect of calcium propionate on mildew and anticorrosion will be enhanced as the temperature rises, but after exceeding a certain temperature, it may lead to volatilization of propionic acid and other problems, rather than make the effect decline.

Humidity: High humidity environment is favorable to the growth and reproduction of microorganisms, and may also affect the distribution and effect of calcium propionate in the product. If the humidity is too high, a water film will easily form on the surface of the product, which will dilute the concentration of calcium propionate and make it less effective. In addition, humidity may also affect the sensitivity of microorganisms to calcium propionate, and under high humidity conditions, microorganisms may become more tolerant to calcium propionate.

Microbial species: Different species of microorganisms have different sensitivities to calcium propionate. Generally speaking, molds are more sensitive to calcium propionate, while some bacteria and yeasts are relatively more tolerant to it. For example, common bread mold bacteria such as Penicillium, Aspergillus, etc., are more sensitive to calcium propionate, a lower concentration of calcium propionate can effectively inhibit its growth; but some bacteria such as lactobacilli, may need a higher concentration of calcium propionate in order to play an inhibitory role.

Product ingredients: Other ingredients in the product may also interact with calcium propionate, thus affecting its mold and preservative effect. For example, some proteins, fats, carbohydrates and other ingredients may bind to calcium propionate and reduce its concentration in the free state, thus affecting its antimicrobial activity. In addition, some additives such as antioxidants and emulsifiers may have synergistic or antagonistic effects with calcium propionate. For example, some antioxidants may enhance the antimicrobial effect of calcium propionate, while certain emulsifiers may weaken its effect.