Location: Commodity Utilization ResearchTitle: Chemical analysis of fermentable sugars and secondary products in 23 sweet sorghum cultivars
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2017
Publication Date: 9/5/2017
Citation: Uchimiya, M., Knoll, J.E., Anderson, W.F., Harris-Shultz, K.R. 2017. Chemical analysis of fermentable sugars and secondary products in 23 sweet sorghum cultivars. Journal of Agricultural and Food Chemistry. 65(35):7629-7637.
Interpretive Summary: Breeding is the primary tool to manipulate the stem sugar composition of sweet sorghum to expand its commercial viability. This study investigated how different inbred and their hybrid varieties are able to increase or decrease key secondary products (organic acid and polyphenols) in stem juice. Predictive correlations were obtained between the juice composition and different cultivars, allowing farmers to select the most marketable cultivar to grow for target niche market.
Technical Abstract: Sorghum, Sorghum bicolor (L.) Moench, is a heat- and drought-tolerant crop that has a promise to supplement corn (Zea mays L.) for biofuel production from fermentable sugars (for sweet varieties) and lignocellulosic biomass. Quantitative relationships are lacking to predict the accumulation of primary (stem sugars) and secondary (organic acids, phenolics, and inorganic species) product that could either expand (as the value-added product) or limit (as the fermentation inhibitor) the market value of a cultivar. Five male (Atlas, Chinese, Dale, Isidomba, N98) and three female (N109B, N110B, and N111B) inbred lines and their hybrids (23 cultivars total) were planted on a Tifton loamy sand in April, May, and June of 2015 in a triplicate split-plot design, and were harvested at the hard-dough maturity stage. Stalk juices were analyzed for sugar (glucose, fructose, sucrose) and organic acid (citrate, oxalate, and cis- and trans-aconitic acid) concentrations, Brix, pH, electric conductivity (EC), total organic carbon (TOC) and total nitrogen (TN), and by fluorescence excitation emission spectrophotometry with parallel factor analysis (EEEM/PARAFAC). Later planting consistently (p<0.05) (1) increased sucrose, total sugar, and trans-aconitic acid concentrations, Brix, and TOC and (2) decreased EC; sucrose, total sugar, pH, EC, and Brix showed significant cultivar×planting date interactions. Observed linear relationships (Pearson’s) could be used to deploy simple and inexpensive electrode (EC) and fluorescence-based field methods to predict the primary products from secondary products, and vise versa.