Detection of Corn Adulteration in Brazilian Coffee (Coffea arabica) by Tocopherol Profiling and Near-Infrared (NIR) Spectroscopy.

Coffee is a high-value commodity that is a target for adulteration, leading to loss of quality and causing significant loss to consumers. Therefore, there is significant interest in developing methods for detecting coffee adulteration and improving the sensitivity and accuracy of these methods. Corn and other lower value crops are potential adulterants, along with sticks and coffee husks. Fourteen pure Brazilian roasted, ground coffee bean samples were adulterated with 1-20% of roasted, ground corn and were analyzed for their tocopherol content and profile by HPLC. They were also analyzed by near-infrared (NIR) spectroscopy. Both proposed methods of detection of corn adulteration displayed a sensitivity of around 5%, thus representing simple and fast analytical methods for detecting adulteration at likely levels of contamination. Further studies should be conducted to verify the results with a much larger sample size and additional types of adulterants.

Phytosterol and tocopherol components in extracts of corn distiller's dried grain.

As the ethanol industry continues to grow, it will become very important to develop value-added markets for its coproducts in order for the industry to remain profitable. Corn distiller's dried grain (DDG) is a major coproduct of ethanol fermentation from corn processed by dry-milling and is primarily sold as livestock feed. The objective of this research was to determine if valuable phytochemicals found in corn oil and corn fiber oil, such as phytosterols and their saturated equivalents, phytostanols, ferulate phytosterol esters (FPE), tocopherols, and tocotrienols, are retained in DDG. Hexane and supercritical carbon dioxide (CO2) extracts of DDG were similar in their concentrations of total phytosterols (15.8-17.3 mg/g of extract), FPE (3.75-3.99 mg/g of extract), and tocols (1.7-1.8 mg/g of extract). Ethanol extracts were slightly lower in concentration of phytosterols (8.9-11.4 mg/g of extract), FPE (1.62-1.98 mg/g of extract), and tocols (0.73-0.76 mg/g of extract).

Effect of elevated temperature on development of tocopherolquinones in oils.

Studies were conducted to determine the formation of tocopherolquinones (TOCQ) in heated sunflower (SUN) and soybean (SBO) oils with and without enrichment with added alpha-tocopherol (alpha-TOC). Samples of the heated oils were extracted with acidified hot methanol and analyzed for changes in TOC contents and TOCQ levels by high-performance liquid chromatography (HPLC). In the oils without added alpha-TOC, the alpha-TOC in SUN significantly decreased from 829 ppm at 0 h to 183 ppm at 5 h and to 0 ppm by 10 h. In contrast, alpha-TOCQ increased from 0 ppm at 0 h to 87 ppm at 5 h and 104 ppm at 10 h. The level of alpha-TOC in SBO decreased from 138 ppm at 0 h to 99 and 98 ppm after 5 and 10 h, respectively, with an increase in alpha-TOCQ from 0 ppm at 0 h to 29 ppm at 5 h and 53 ppm at 10 h. In the oils with added alpha-TOC, the alpha-TOC in the SUN decreased rapidly from 1128 ppm at 0 h to 225 ppm at 5 h and 28 ppm at 10 h; however, the alpha-TOC in the SBO was 1176 ppm at 0 h, 367 ppm by 5 h, and 242 ppm at 10 h. There was a corresponding increase of alpha-TOCQ in SUN with added alpha-TOC from 0 ppm at 0 h, 127 ppm at 5 h, and 164 ppm at 10 h, whereas the alpha-TOCQ in SBO with added alpha-TOC changed from 0 ppm initially to 159 ppm by 5 h and 187 ppm at 10 h. As expected, SUN with no added alpha-TOC formed significantly more alpha-TOCQ than the SBO. However, SBO with added alpha-TOC had significantly more alpha-TOCQ than the SUN with added alpha-TOC even though the alpha-TOC levels at 0 h were similar. These results indicate that TOCQs are formed easily from the decomposition of alpha-TOC and could be potential antioxidants even as alpha-TOC decomposes.