Location: Commodity Utilization ResearchTitle: Impact of storage on sugar loss in sorghum stalks
Submitted to: African Journal of Agricultural Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2019
Publication Date: 10/1/2019
Citation: Wright, M. 2019. Impact of storage on sugar loss in sorghum stalks. African Journal of Agricultural Research. 14(33):1629-1634. https://doi.org/10.5897/AJAR2019.14232.
Interpretive Summary: Sweet sorghum has potential as a feedstock for bioproducts production due to its ability to grow in marginal soils that are low in moisture and fertilization. The return on the financial investment in equipment used to collect and process juice from sorghum stalks can be enhanced by extending processing past harvest season. A limitation of storing sorghum juice for delayed processing is the degradation of sugar in the juice. Degraded sugars are no longer available for fermentation into bioproducts. Microbes in the environment are a source of sugar degradation. The ability to store sorghum stalks after harvest would extend output from the mill and increase profitability. This work evaluates the degree of sugar loss in billets of the size prepared commercially, and whole stalks.
Technical Abstract: Sweet sorghum is a potential feedstock for production of bioproducts due to the sugar content in its stalks, tolerance of drought conditions, and ability to grow in low quality soils. The ability to extend production beyond harvest season will benefit the investment in machinery and staffing by maximizing profitability. A limitation to extending production is loss of fermentable sugars during storage. Cutting stalks into 4 in or 8 in billets during harvest increases surface area for processing efficiency, but can also increase sugar degradation. Storing whole sorghum stalks prior to processing was investigated as a means to increase sugar stability. Sugar loss differed between the sorghum cultivars studied. M 81-E lost 40.1% of fermentable sugars and 64.6% of sucrose by day 4 averaged across all three lengths. Whole M 81-E stalks had the highest losses at 44.2% of fermentable sugars and 68.5% sucrose. Also by day 4, Topper lost 46.6% fermentable sugars and 76.7% sucrose. Whole Topper stalks lost less fermentable sugar, 43.1%, than 8 in billets, 59.3%, but still had a greater loss of sugar than 4 in billets. Storage of whole stalks was found to not increase stability of sugars in sorghum juice between harvest and processing.