Antioxidant potential of extracts from peels and stems of yellow-fleshed and white cassava varieties

Open Access Article; Published online: 24 Sep 2020This study focused on the exploration of the potentials of extracting antioxidants from peels and stems of yellow‐fleshed and white cassava varieties. The effect of particle size (0.2 and 0.5 mm) and variety on the phenolic content and antioxidant activity was assessed. The peels of the yellow‐fleshed cassava variety with a particle size of 0.2 mm showed the highest phenolic content with 681.5 GAE mg 100 g−1 and antioxidant activity of 19% and 425 μM TE g−1 dry matter using DPPH and FRAP assays respectively. The stems of the white cassava with a particle size of 0.2 mm exhibited high phenolic content (442.4 GAE mg 100 g−1) and antioxidant activity of 12.8% and 234 μM TE g−1, better than the stem of the yellow‐fleshed cassava. These results indicate that phenolic and antioxidant extractions were influenced by variety, the plant parts and particle size for the antioxidant assays

Comparative Characterization of Petrophysical and Mechanical Properties of Siliciclastic Reservoir Rocks within a compressional structure of the Teapot Dome Oilfield, Wyoming, USA

Working with subsurface engineering problems in Hydrocarbon exploration as regard rock elastic and petrophysical properties necessitate accurate determination of in-situ physical properties. Several techniques have been adopted in correlating log-derived parameters with petrophysical and mechanical behavior of the rocks. However, limited field applications show there are no particular parameters and correlations that are generally acceptable due to the regional variation in geologic features (i.e., degree of mineralogy, texture, etc.). This study presents a method that assesses the disparity in petrophysical properties of oil and gas reservoir rocks in relation to their elastic/mechanical properties from 10 well-logs and 3D migrated seismic data. Two distinct facies were identified from seismic data after computing attributes. Reflection strength attribute of 2.5 and above depicts Bright spots within the central section of the field as clearly revealed by Variance and Chaos attributes. Formation properties calculated from logs were conformally gridded in consonance with the reflection patterns from the seismic data. The average Brittleness index (BI) of 0.52 corresponds to Young's modulus (E) values of between 8 and 16 for the dense portion. This portion is the laminated, reasonably parallel, and undeformed part, flanked by the unlaminated and chaotic zones. From cross plots, the distinguished lower portion on the plot is the segment with higher sand of more than 50 %. This segment corresponds to the reservoir in this study as confirmed from the genetic algorithm neural network Acoustic impedance inversion process result. Similarly, the plot of Compressional velocity (Vp) and Poisson’s ratio (ν), reveals the laminated sand value of not less than 0.32 of ν, and Vp of about 4.2 km/s. The average porosity is about 16 %, average water saturation is about 16 %, and average permeability is approximately 25 md. Rock properties trends in a unique pattern and showing fluctuation that confirms the compressive nature of the structure with corresponding petrophysical properties. This trend is sustained in permeability computed and suggests a significant gravity-assisted compaction trend and fluid movement. It gives a reasonable idea of the fluid movement interplay and mechanical property variation within the sequence and across the dome. This part probably has been subjected to fair compressional deformational forces initiated from outside the survey

Amylose, rheological and functional properties of yellow cassava flour as affected by pretreatment and drying methods

This study reconnoitered the effects of preservative treatments (0.3% Sodium Metabisulphite solution (SMS); and 0.3% Citric Acid solution (CAS)) and drying methods (flash- and cabinet-drying) on the rheological profile, amylose and functional properties of flour from yellow-fleshed cassava varieties. Four preservative-treated flour samples (Sodium Metabisulphite cabinet-dried (SMC); Sodium Metabisulphite flash-dried (SMF); Citric Acid cabinet-dried (CAC); and Citric Acid flash-dried (CAF) were evaluated. The rheological profile (peak, breakdown, setback and final viscosity) of flash-dried samples treated with sodium metabisulphite exhibited the highest values (891 RVU, 586 RVU, 208 RVU and 513 RVU) respectively. The cabinet-dried samples treated with citric acid had the least peak, trough and final viscosity of 497 RVU, 211 RVU and 326 RVU respectively. The flash-dried flour samples had the highest values for water absorption capacity while cabinet-dried (CAC) flour samples had the highest dispersibility. Therefore, flash-dried flour samples are more likely suited for food formulations requiring good pasting quality and moderately high gel strength

Studies on the Characteristic Properties of Fermented, Sun-Dried Orange- Fleshed Sweet Potato Flour

Microbiological, functional, chemical and sensory properties of flours of two (2) cultivars of orange-fleshed sweet potato (centinnial and CIP 440293) being multiplied for distribution in South East and South-South Nigeria were investigated using standard techniques. The flours were observed to have good functional properties and high dry matter contents which were respectively 88.09 ± 0.00% and 86.0 ± 0.00%. The respective values for fat content (0.85 ± 0.00% and 1.75 ± 0.00 %), ash content (2.04 ± 0.00% and 2.40 ± 0.42%) and crude fibre content (2.90 ± 0.28% and 2.67 ± 0.00%) were low but the respective levels of carotenoids values (3.74 ± 0.00 and 5.28 ± 0.00 μg/g) were high indicating a promising source of pro-vitamin A. The sensory evaluation had no statistical difference among the parameters. The flours had high nutritive values with good functional and sensory properties. The microbial loads were within the acceptable limit of < 105 recommended by ICMSF, making the flour samples microbiologically safe and with appropriate packaging, the shelf life could be extended under good storage conditions.Keywords: Orange-fleshed sweet potato, flour, sun-drying, physicochemical properties, functional properties