Sorghum value chain analysis in semi-arid Zimbabwe

The role of extension in strengthening relationships among stakeholders along agricultural commodity value chains remains an important discussion point especially with orphan crops in semi-arid areas. The study used a participatory framework to analyse the sorghum value chain in the Mid Zambezi Valley of Zimbabwe. A sample comprising of 380 small scale farmers, proportionately selected from five major sorghum producing wards, was used. Six agrodealers, 15 traders, 10 retailers, three wholesalers, and two processors were also sampled. Inaddition, focus group discussions, informant interviews, questionnaires and reviews of records were conducted. Input supply systems for sorghum are weakly developed and production is stalled by inappropriate innovations including seed and fertilizer application. Marketing and processing channels are limited due to erratic supply and low producer prices. Demand for sorghum inputs can be created by engaging extension agents in helping farmers with realising the benefits of using improved sorghum seed varieties and fertilizer in sorghum production. This will smoothen the flow of sorghum products along strategic value chain nodes.Keywords: Sorghum, small scale farmers, value chain, extension networks, marketing margins, agribusines

Southern African indigenous fruits and their byproducts : prospects as food antioxidants

CITATION: Pfukwa, T. M., et al. 2020. Southern African indigenous fruits and their byproducts : prospects as food antioxidants. Journal of Functional Foods, 75:104220, doi:10.1016/j.jff.2020.104220.The original publication is available at https://www.sciencedirect.comPublication of this article was funded by the Stellenbosch University Open Access FundThe discourse regarding plant-based preservatives for food application has generally revolved around extracts from commercial fruits, vegetables, herbs and spices with indigenous fruits (IFs) on the periphery, with little investment into their valorisation. While being important food sources at community level, IFs and their byproducts are also incorporated into medicinal remedies, combating various diseases. Their ethnomedicinal usage indicates potent bioactive profile that alleviate effects of oxidative stress, which accompany disease in vivo. This is supported by in vitro antioxidant activity of the IFs and their byproducts. As such, the current review explores the potential of bioprospecting extracts from nine IFs and their byproducts as food antioxidants. Evidence presented shows that IFs have high content of bioactive compounds further translating to high antioxidant activity. Research gaps in information concerning in vitro bioactivity warrant further research to provide impetus for valorisation and food application of IFs.https://www.sciencedirect.com/science/article/pii/S1756464620304448Publisher's versio

Temperature-Induced Effects on the Structure of Gramicidin S

We report on the structure of Gramicidin S (GS) in a model membrane mimetic environment represented by the amphipathic solvent 1-octanol using one-dimensional (1D) and two-dimensional (2D) IR spectroscopy. To explore potential structural changes of GS, we also performed a series of spectroscopic measurements at differing temperatures. By analyzing the amide I band and using 2D-IR spectral changes, results could be associated to the disruption of aggregates/oligomers, as well as structural and conformational changes happening in the concentrated solution of GS. The ability of 2D-IR to enable differentiation in melting transitions of oligomerized GS structures is attributed to the sensitivity of the technique to vibrational coupling. Two melting transition temperatures were identified; at Tm1 in the range 41–47 °C where the GS aggregates/oligomers disassemble and at Tm2 = 57 ± 2 °C where there is significant change involving GS β-sheet-type hydrogen bonds, whereby it is proposed that there is loss of interpeptide hydrogen bonds and we are left with mainly intrapeptide β-sheet and β-turn hydrogen bonds of the smaller oligomers. Further analysis with quantum mechanical/molecular mechanics (QM/MM) simulations and second derivative results highlighted the participation of active GS side chains. Ultimately, this work contributes toward understanding the GS structure and the formulation of GS analogues with improved bioactivity