National Organic Standards Board

Crops Committee

Corn Steep Liquor

Synthetic/Nonsynthetic Determination

Revised Committee Decision Discussion

October 7, 2010

Discussion

A number of issues emerged in the committee’s deliberations on CSL that span a range of 

concerns, based on what we know and what we do not know about its manufacturing process.

The fundamental issue that the committee confronts is applying the definition of chemical 

change against the mechanism occurring in the CSL production process. Two issues emerge 

here, the first (chemical changes) being a threshold issue that obviates the need for further 

consideration of the second (synthetic residuals).

Chemical Change

The Technical Review (TR) (29-30) states that, “The major objectives for corn steeping are to 

induce chemical and physical changes in the kernel by leaching the soluble components from 

the corn. “ It goes on to say that “sulfur dioxide is added at rates of 0.1 to 0.2 percent and is 

used to cleave disulfide linkages, resulting in the degradation of the corn protein that 

encapsulates the starch granules. “ (TR 99-102) The cleavage process breaks chemical 

bonds, thus releasing amino acids from the protein matrix into the CSL liquid.

OMRI looked at CSL and reached the conclusion that “sulfurous acid induces chemical and

physical changes in the kernel, in effect, separating the starch and insoluble protein by 

cleaving protein disulfide cross-links in the endosperm protein matrix (OMRI Materials Review, 

Spring 2010) Research finds that the steeping process creates chemical changes that release

soluble proteins in the steepwater. According to Biss and Cogan (1996), “The introduction of 

SO2 into the process is accompanied by a rapid increase of the soluble proteins as a result of 

an accelerated degradation of the corn [heretofore] insoluble proteins (Biss and Cogan 

1988).”

1

 

1Biss and Cogan state, ”It is generally accepted that lactic acid is beneficial for corn steeping, due to its 

softening action on cell walls (Watson 1984) and possibly due to induction of some proteolytic activity 

which enhances protein degradation (Watson et al 1955, Roushdi et al 1981). The major role of sulfur 

dioxide in steeping is to cleave disulfide linkages, thereby loosening the protein matrix that 

encapsulates the starch granules (Watson 1984). The introduction of SO2 into the process is 

accompanied by a rapid increase of the soluble proteins as a result of an accelerated degradation of 

the corn insoluble proteins (Biss and Cogan 1988)” (“Sulfur Dioxide in Acid Environment Facilitates 

Corn Steeping,” 1996)
Corn Steep Liquor 

Synthetic/Nonsynthetic Determination

Updated October 7, 2010

Page 2 of 3

Incomplete information and manufacturing variability

Unanswered questions and lack of uniformity in process and outcome raise concern. The TR

(167-169) states that, “[T]he chemical composition of corn steep liquor will probably vary and is 

reflective of the processing strategy used by a particular manufacturer, depending on which 

corn component they are interested in isolating.” The TR characterizes the manufacturing of 

CSL as a “complicated process of chemical and biochemical reactions that, despite the long 

history of the wet-milling industry, are still not fully understood.” (TR 192-194)

In addition to uncertainties concerning the traditional wet-milling process, there are further 

questions and concerns that arise from the recent use of a new process, for processing corn to 

ethanol, that results in a byproduct also called “corn steep liquor.” The new process results in 

higher-sulfur CSL, a product that could actually be dangerous when used as a livestock feed 

ingredient2in the same ways that traditional CSL has been used.

Application of classification of materials policy

Regardless of the uncertainties mentioned above, the best available evidence and scientific 

understanding indicate that chemical change does occur in the process of steeping corn. The 

policy allowing synthetics in processing at levels that are determined not “significant,” thus 

does not, first and foremost, come into play with CSL The use of sulfur dioxide in this case is 

not incorporated into wet milling as part of an additive process, but rather as an agent that is 

intended to change the chemical and physical characteristics of an agricultural product. In this 

context, the committee believes that the significant issue of sulfur residuals is not the central 

issue, although important given its synthetic character and contravening the existing prohibition 

of adding sulfur in the processing of organic corn products. While it may be unclear as to 

whether the lactic acid fermentation results in the cleavage of any of the disulfide bonds, it is 

established that the addition of sulfur dioxide does result in the cleavage of those bonds. 

Regardless, confusion only strengthens the need for the committee to take a precautionary 

approach based on the worst case scientific understanding. Lack of understanding or 

disagreement in the scientific community is not, in the committee’s opinion, an adequate basis 

for moving forward with an allowance.

If the committee were to focus on the mere introduction of sulfur dioxide and its remaining 

residuals in the finished CSL product, applying the policy voted on by the NOSB at its 

November 2009 and April 2010 meetings, we would now confront the question of the 

allowance of proposed policy changes in light of underlying statutory and rule making 

standards. While the NOSB voted to adopt policy changes on the classification of materials the 

standards have not been promulgated and have raised legal questions regarding compatibility 

with existing rules under OFPA.3

 

2

"Too much sulfur destroys thiamine in the rumen, leading to thiamine deficiency and 

polioencephalomalacia (PCM, also known as "Brainers," or "Polio"). Theuer, July 30, 2010.

3

Subsequent to the committee discussion on CSL, the NOP in a September 30, 2010 memo to the NOSB, 

entitled “Memorandum for the Chairman of the NOSB,” on the Board’s April 2010 and November 2010 

recommendations found that the NOSB classification of materials policy change “adds a meaning to 
Corn Steep Liquor 

Synthetic/Nonsynthetic Determination

Updated October 7, 2010

Page 3 of 3

Future uses of CSL or other products associated with sulfur-based wet milling 

processing

The committee in this decision is not passing judgment on the future uses of CSL or other 

products derived from the sulfur-based wet milling process. The committee decision focused 

on whether the sulfur-based wet milling process effects a chemical change. The committee, 

however, is aware that “crop products could use synthetic substances already allowed in 

organic crop production. (TR 243-244) The same is true for livestock producers. (TR 250-251)

Additionally, while there are questions about the quality of the end-products, “[W]et corn milling 

could be conducted without sulfur dioxide, the lactic acid fermentation and the subsequent 

separation of the corn components (including natural drying to concentrate the soluble 

materials in the liquid portion) may be another method of processing the corn.” (TR 225-227)

Ultimately, however, CSL can still be petitioned for inclusion on 205.601 to be placed on the 

National List and used as an input in liquid fertilizers allowed in organic crop production.

 

the term chemical change” that is contrary to common understanding of a widely used term.” The 

memo point out that “a substantive rule” cannot be contained in the definition, finding that, “The 

proposal to exempt certain processing methods and synthetic materials from causing the effect of 

chemical change is a substantial regulatory provision, which conflicts with the common understanding 

of chemical change...“