This work was designed to elucidate selected physicochemical, functional, and structural properties of native and modified yam (Dioscorea rotundata) starch. The isolated starch was chemically modified using 5, 10, 15, 20, and 25% phosphoric acid solution at 50°C for 1 h, and yield, swelling power, gelation, water holding capacity, paste clarity, blue value, and amylose and amylopectin content of the native and modified yam starch were determined. Structural changes in the native and starch modified with 25% phosphoric acid were evaluated using Fourier transform infrared spectroscopy and optical microscopy. The result showed that the yield, swelling power, water holding capacity, paste clarity, blue value and amylose and amylopectin content of native yam starch was 33.38% (217 g), 3.84 g/g, 1.0 v/g, 10%, 0.52 and 25.96, respectively, whereas gelation study of the native and modified starch indicated that native starch was viscous and modified starch firm. However, yield, swelling power, water holding capacity, paste clarity, blue value, and amylose content of modified yam starch reduced in a dose dependent manner with phosphoric acid. The reduction in the values of the various functional properties could be associated with the effect of phosphoric acid on the starch granular structure. The result of Fourier transform infrared spectroscopy and optical microscopy revealed that the yam starch was modified by phosphoric acid with changes in functional groups spectra such as-OH stretch (3177 cm −1), H 2 O absorbed (1644 cm −1) (amorphous region), C-H stretch (2923 cm −1), CH 2 O (1253 cm −1), and CO -C (1078 cm −1) when compared to native starch. The morphology of native and modified yam starch granules ranged from oval to eliptical. However, modified starch granules were rough in surface. In conclusion, the characterized physicochemical and functional properties and structure exhibited by native and modified yam starch indicated that, yam could be a cheap and valuable source of starch for industrial application.

This study was designed to compare some functional and structural properties of yam (Dioscorea rotundata) and cocoyam (Colocasia esculenta) starches. The yield, swelling power, amylose content, paste clarity, and viscosity of yam and cocoyam starches were determined. Likewise, the structural conformation of the starches was evaluated using optical and scanning electron microscopy as well as FTIR spectroscopy. The result showed that, the yield, swelling power, amylose content, and paste clarity of yam and cocoyam starches were 33.38% (217 AE 0.88 g) and 25% (108.75 AE 0.88 g); 38.4 AE 0.2 g/g and 33.4 AE 0.1 g/g; 25.96 AE 0.16 and 22.99 AE 0.04 and 44 AE 2% 34 AE 1% and 350 AE 15.28 and 210 AE 10 mPa.s, respectively. The yield, swelling power, amylose content, paste clarity, and viscosity of yam starch were significantly higher (p < 0.05) than from cocoyam starch. The result of FTIR spectroscopy of yam and cocoyam starches at -OH stretch was 3176.45 and 3251.60 cm À1, respectively. At -OH stretch cocoyam starch gives higher absorption intensity and broader shape than yam starch, which could be attributed to higher crystallinity of cocoyam starch granules compared to yam starch. The optical and scanning electron microscopy indicated that the granular shape of yam starch was oval whereas cocoyam starch was polygonal with fissures and cavities. In conclusion, from the various functional and structural properties of yam and cocoyam starches evaluated, both could be a cheap and good sources starch, which could be worked for industrial application.

Aim:The aim of this study was to chemically modify the starch extracted from Manihot esculentus with an objective of gaining insight into the structure and architecture of the native and modified starch. Study Design: Experimental. Methodology: Starch from tubers of cassava (M. esculentus) was extracted and chemically modified using a 95% ethanol solution containing 20% HCl at 50°C for 1-4 hours. Structural changes in the native starch and its derivatives were evaluated using colorimeter on treatment with Iodine-KI solution, and the absorbance read at wavelength (λ=470 nm). The gelatinization temperature of the starch was also determined. Results and Discussion: From the result, absorbance of the acidified ethanol modified starch decreased per hour after treatment with Iodine solution while the weight of recovered derivatives went accordingly. The gelatinization temperature of the modified starch increased with respect to the time taken. Conclusion:In conclusion, there was an indication that acidified ethanol changed the starch structure and architecture with a corresponding effect on the gelatinization temperature, easy drying and reaction with Iodine solution. The process of modification of the starch gave rise ethyl-O-starch. In addition, starch modified with HCl/ethanol obeys the Lambert-beer law and the rate of Original Research Articlehydrolysis of its molecular chains could be monitored and calculated. Therefore, cassava starch modified with acidified ethanol could find applications in food, textile and paper industries.

Background The prevalence and death rate arising from malaria infection, and emergence of other diseases showing similar symptoms to malaria require the development of malaria-specific and sensitive devices for its diagnosis. To address this, the design and fabrication of low-cost, rapid, paper-based analytical devices (µPAD) using surface-immobilized aptamers to detect the presence of a recombinant malarial biomarker—Plasmodium falciparum lactate dehydrogenase (rPfLDH)—is reported in this study. Methods Test zones on paper surfaces were created by covalently immobilizing streptavidin to the paper, subsequently attaching biotinylated aptamers to streptavidin. Aptamers selectively bound rPfLDH. The measurement of captured rPfLDH enzyme activity served as the means of detecting this biomarker. Enzyme activity across three replicate sensors was digitally quantified using the colorimetric Malstat assay. Results Screening of several different aptamers reported in the literature showed that aptamers rLDH7 and 2008s immobilized in this manner specifically recognised and captured PfLDH. Using rLDH7, the sensitivity of the µPAD sensor was evaluated and the µPAD sensor was applied for preferential detection of rPfLDH, both in buffered solutions of the protein and in spiked serum and red blood cell lysate samples. In buffered solutions, the test zone of the µPAD sensor exhibited a KD of 24 ± 11 nM and an empirical limit of detection of 17 nM, respectively, a limit similar to commercial antibody-based sensors exposed to rPfLDH. The specific recognition of 133 nM rPfLDH in undiluted serum and blood samples was demonstrated by the µPAD. Conclusion The reported µPAD demonstrates the potential of integrating aptamers into paper-based malarial rapid diagnostic tests. Graphical Abstract

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