Location: Commodity Utilization ResearchTitle: Electrochemical evaluation of sweet sorghum fermentable sugar bioenergy feedstock
Submitted to: ACS Sustainable Chemistry & Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2017
Publication Date: 8/7/2017
Citation: Uchimiya, S., Knoll, J.E., Harris-Shultz, K.R. 2017. Electrochemical evaluation of sweet sorghum fermentable sugar bioenergy feedstock. ACS Sustainable Chemistry & Engineering. (5):7352-7364.
Interpretive Summary: Electroactive components of agricultural commodities, including sorghum, are responsible for key quality traits including pest resistance. This study developed new cyclic voltammetry-based methods to quantitatively detect electroactive components of stem juice in sweet sorghum. Developed easy, rapid, cheap method can be used to screen phenotypes to select pest-resistant varieties.
Technical Abstract: Redox active constituents of sorghum, e.g., anthocyanin, flavonoids, and aconitic acid, putatively contribute to its pest resistance. Electrochemical reactivity of sweet sorghum stem juice was evaluated using cyclic voltammetry (CV) for five male (Atlas, Chinese, Dale, Isidomba, N98) and three female (N109B, N110B, and N111B) inbred lines and their hybrids (23 cultivars total) planted in April, May, and June of 2015 in Georgia, and harvested at the hard-dough stage. The peak anodic potential (Epa in volts) of derivative CV (pH 5, 0.1 M KCl) overlapped with quercetin and tannic acid model reductants. Fluorescent porphyrin/chlorophyll-like condensed aromatic structure is likely to be the primary electron-enriched moiety in juice. This putative reductant had the highest contribution to the inbred line N109B, which had the highest integrated (Gaussian and trapezoidal) CV peak areas in the May planting. In the June planting, hybrid N109A'Atlas had the highest CV area, and received the highest contribution from a fluorescent fingerprint having lower aromaticity than the porphyrin/chlorophyll-like structure. The hybrid N110AxAtlas was the most easily oxidizable variety in the June planting, with the lowest Epa. While aconitic and other aliphatic carboxylates could be electroactive, condensed aromatic structures are likely to be the primary electroactive components of sweet sorghum juice, which requires sufficiently high potential to oxidize (resulting in more positive Epa), and donates the largest number of electrons (highest CV peak areas).