In 1978, German researchers reported finding low levels of dimethylnitrosamine (DMNA) in beer. Subsequent studies provided evidence that the DMNA found in beer was derived from the barley malt used for making beer and other malt beverages.
Barley malt is produced by moistening barley with water, allowing it to germinate, and then drying (kilning) the barley to reduce the moisture content to about 4%. DMNA may be formed during the drying process as a result of a reaction between amines, which are naturally present in the barley, and a nitrosating agent, such as nitrogen oxides (NOx), which may be present in the air or may be formed during combustion of the fuel used for firing.
The addition of sulfur when direct fire is used for drying has been shown to reduce DMNA formation. Studies also have indicated that the use of indirect fire during kilning generally results in nondetectable levels of DMNA. This finding may be correlated with the fact that, during indirect firing, the combustion products do not come in contact with the amines as they would when an open flame or direct fire is used. However, the use of indirect fire does not always ensure elimination of DMNA in the malt. Evidence indicates that even when indirect fire is used, DMNA may be derived from the ambient air. This problem has been reported by malt producers who use indirect fire and are located in industrial areas.
A survey of all known malt producers in the U.S. was conducted in 1980. Data from the survey provided evidence that within the technology available to the industry at the time of the survey, barley malt containing less than or equal to 10 ppb DMNA could be produced. Therefore, DMNA in barley malt at levels greater than 10 ppb is considered avoidable contamination under section 406 of the Federal Food, Drug, and Cosmetic Act. The action level of 10 ppb DMNA in barley malt applies to all barley malt produced after October 1, 1980.
REGULATORY ACTION GUIDANCE:
The following represents criteria for recommending legal action to CFSAN/Office of *Compliance*/Division of Enforcement (HFS-605):
Actionable if a composite of 10 subsamples of finished product barley malt contains greater than 10 ppb dimethylnitrosamine and the presence of dimethylnitrosamine is confirmed by mass spectrometry.
NOTE: Refer to IOM sample schedules for "Pesticides Sampling" (Chart 3) and "Wheat Carload Sampling" (Chapter 4) for sampling instructions.
See Sec. 510.600 (for CPG 7101.07) for action level for DMNA in malt beverages.
*Material between asterisks is new or revised.*
Revised: 10/1/80, 6/6/88, 3/95, 5/2005