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Kemin Industries Inc. has created a personal care division, Kemin Personal Care Inc., and has made its debut with five personal care ingredient launches. One of the ingredients, MicroCurb (INCI: Natural Propionic Acid) is a natural broad-spectrum preservative made from fermented soy extract that is said to be effective against Gram-positive and Gram-negative bacteria (E. coli, S. aureus and P. aeruginosa), mold (A. niger) and yeast (C. albicans).
The occular irritation of the material was determined using a Bovine Corneal Opacity and Permeability Test (BCOP). Relative irritancy is classified according to BCOP score and the score of the soy preservative rated1.24, which is considered a mild irritant, whereas a moderate irritant ranges from 25.1–55 or a strong irritant > 55.1.
The preservative was also tested for skin irritation using a Mattek Epiderm MTT Viability Assay. Relative irritancy is classified according to ET50 scores. The ET50 for the preservative was found to be > 24 hr, indicating it is a non-irritant to the skin, compared with a very mild irritant (12–24 hr), a moderate to mild irritant (4–12 hr), a moderate irritant (0.5–4 hr) and a severe irritant (< 0.5 hr).
The preservative is water-soluble and recommended at 3%; it is a beige/tan solid with a prevalent odor and a density of 0.3–0.5 g/cc. In addition, in a 10% solution, it has a pH of 8–10.