Blue denim is the most loved of fabrics. There is more than one way to make its color. CutisBio produces indigo using the biosynthetic pathways of microorganisms together with fermentation.
CutisBio R&D Team
1. Why we check for impurities
Aniline and N-methylaniline are starting materials or intermediates for chemically synthesized indigo, and they can remain as unreacted residues in the final powder. Because of their toxicity and possible carcinogenicity, certification standards including ZDHC, OEKO-TEX and GOTS limit the permitted concentration of these substances in textile dyes and in finished products. That is why we analyze both substances for each product and publish the results together with the detection limit.
Chemical structures of aniline and N-methylaniline
Aniline
C₆H₅NH₂ · CAS 62-53-3
N-methylaniline
C₆H₅NHCH₃ · CAS 100-61-8
This description does not exceed the scope stated on p.4 of the catalog (starting materials, intermediates, toxicity, carcinogenic potential).
Skeletal formulae drawn directly in code (SVG) from verified chemical structures. They were not produced with an image generation tool.
2. Indigo made by microbial fermentation
CutisBio uses a fermentation process that draws on the biosynthetic pathways of microorganisms to convert tryptophan obtained from biomass into indigo. Of the four indigo synthesis routes presented in the catalogue, this is the microbial route.
3. What the tests confirmed
In KATRI's ASTM D6866-24a Method B test, biobased carbon content was measured at 98% (pMC 97.73), and in KOTERI's KS K 0734 2019 test aniline and N-methylaniline were not detected (method detection limit 5 mg/kg). According to the catalogue, colorfastness is at a level comparable to plant and chemical indigo, and the grade for each item can be seen exactly as recorded in the tables on the data page.
The certificates included in the provided catalog. You can check the originals as is.
ZDHC MRSL Level 1 Version 3.1
Within the validity period stated in the document
Certification material included in the July 2026 catalogue
Certificate number
H682-25-00154
Certification body
FITI Testing & Research Institute
Covered product
CB Bio Indigo Dye Powder
Source: Catalogue p.10
The scope covers the chemical formulation named on the certificate (CB Bio Indigo Dye Powder). The use category is Natural dyes (1.7.27).
OEKO-TEX® ECO PASSPORT
Within the validity period stated in the document
Certification material included in the July 2026 catalogue
Certificate number
E2AGHSST4
Certification body
Centexbel (OEKO-TEX® Service GmbH)
Covered product
See attached enclosure — Product category 2.9 Natural dyes
Source: Catalogue p.10
The product list is in the enclosure to the certificate and is not included in the catalogue. The product class is 2.9 Natural dyes. Until the enclosure has been checked, we do not specify the range of covered products.
USDA BioPreferred®
No expiry date is stated in the document
Certification material included in the July 2026 catalogue
Certificate number
4295FD7FF6695D3B1D293DB7DDEE34A5
Certification body
U.S. Department of Agriculture — Rural Development
Covered product
CB Bio Indigo Dye Powder
Source: Catalogue p.11
A participation certificate confirming that the USDA Certified Biobased Product Label was obtained; the label states 98%. Catalogue p.11 footnotes the precision of this result as ±3% (absolute).
TÜV AUSTRIA OK biobased — Class 5
Within the validity period stated in the document
Certification material included in the July 2026 catalogue
Certificate number
TA8072609668
Certification body
TÜV AUSTRIA GMBH
Covered product
CB Bio Indigo Dye Powder (Colour: indigo)
Source: Catalogue p.11
Class 5 means a biobased carbon content of 97% or more and up to 100%. The certificate cites method EN 16640 and certification scheme OK 20 edition D.
We have confirmed the dates written in the documents; this is not a check of current certification status in the certification body's database.
The product name on the certificates is “CB Bio Indigo Dye Powder”. Blugene is the new brand name for the CutisBio bio indigo business, which includes this product, and the product names in the certificate images have not been changed.
The certification scope is limited to the product named on each certificate. It does not mean that digital printing ink or finished denim garments are automatically certified.
Data as of
2026-09-06
Recommended date for the next certification status check
Blugene is the brand name of the bio indigo that CutisBio Co., Ltd. produces by microbial fermentation. In the catalogue and the certificates it is recorded under its original product name, “Bio Indigo Dye Powder (Microbial Fermentation)”.
What does “98% biobased carbon content” mean?
It means that 98% of the carbon in the product comes from renewable feedstock. It is the result of KATRI's ASTM D6866-24a Method B (AMS) test (pMC 97.73, report SBED25-00000153-1, 2025-05-22), and it is not indigo purity or a carbon emissions reduction rate.
Does “aniline not detected” mean the content is 0?
No. It means that in KOTERI's KS K 0734 2019 test the result was below the method detection limit of 5 mg/kg and so was not detected (report 2025-0604-1132-C03, 2025-06-10). It does not mean 0 ppm or the complete absence of the substance.
Can it be used on existing dyeing equipment as it is?
The catalogue records comparable performance to plant and chemical indigo in the dyeing of cotton, silk and cashmere. Results can vary with the mill, the fabric and the process conditions, so we recommend confirming actual application with a fabric sample.
Which products do the certifications apply to?
The product named on the certificates is “CB Bio Indigo Dye Powder”. The product list for OEKO-TEX ECO PASSPORT is in an enclosure to the certificate, so the scope cannot be determined from the catalogue alone. Digital printing ink and finished denim garments are not automatically certified.
