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Detecting Corn Syrup in Barley Malt Extracts

¹United States Department of Agriculture, Agricultural Research Service, Cereal Crops Research, 501 Walnut St., Madison WI 53705. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Department of Agronomy, University of Wisconsin-Madison. ³Corresponding author. Phone: 608-262-4482. Fax: 608-264-5528. E-mail: dmpeter4 @facstaff.wisc.edu

Methods for detecting corn syrup in barley (Hordeum vulgare L.) malt extract were evaluated. Twelve samples representative of commercially available 2-rowed and 6-rowed malting barleys were malted. Extracts prepared from the finely ground malts were analyzed for ¹³C/¹²C ratios, expressed as δ¹³C, and concentrations of protein and sugars. The ¹³C/¹²C ratios were sufficiently different to distinguish corn syrup from malt extract. By calculating the mean values for the barleys, it was determined that a δ¹³C > -24.3‰ indicated that the malt extract had been adulterated with corn syrup (99% confidence). Protein concentrations <4.5% (2-rowed malt) or <5.0% (6-rowed malt) of the extracts also indicated probable adulteration with corn syrup, which is devoid of protein. Because of differences in sugar concentrations between the malt extracts and corn syrup, carbohydrate analysis also indicated probable mixtures. These findings were confirmed by analysis of extracts from composite 2-rowed and 6-rowed barley malts that had been mixed with known quantities of corn syrup. The regressions for δ¹³C, protein concentration, and most sugar concentrations against percent dilution with corn syrup in the mixtures were significant.