Fresh Cassava Tubers Research Articles

Design, Fabrication and Preliminary Testing of a Small-Scale Cassava Starch Extraction Machine

A cassava starch extraction machine was designed and fabricated to perform a quadruplet action of grating, washing, sieving and separation. The study was necessitated based on concerns that most locally manufactured cassava processing machines are without provision for the extraction of starch. Food processors mainly depend on the manual pressing of cassava to obtain starch and this has significantly increased the cost of the product in the local market. Materials for construction were locally sourced and the machine was powered by a 2 hp electric motor through a v-belt-pulley transmission system and operating at a speed of 547 rpm. Fresh cassava tubers were harvested from Ikot Akpaden, a rural community in Mkpat Enin, Akwa Ibom, South-South of Nigeria, and used for the experiment. Results from the experiment showed that the quantity of wet starch extracted increased from 0.64 to 1.48 kg as the volume of water mixed with 2 kg of the product increased from 1 to 5 Liters. The rate of water usage and throughput capacity increased from 0.0005 to 0.0025 m3/kg and 35.29 to 46.75 kg/h respectively as volume of water increased. The optimum machine efficiency was 74%. The machine was fabricated at a cost of N 150,200 (equivalent of $100). Minimal time consumption, ease of operation and low production cost were some of the features that made the machine economically viable when compared to other conventional methods of extracting starch from cassava.

Steroid Compounds of Manihot Esculenta Crantz Var. Sao Pedro Petro (Tuber) and Their Cytotoxic Effects on Melanoma Cancer Cells (B16-F10)

The pharmacological research of Manihot esculenta has stated the potential present as an interesting cytotoxic activity caused by several compounds contained in this species. However, the research on Melanoma Malignant cells (B16-F10 cancer cells) has never been studied. In this study, the steroid compounds isolated from the tuber of Sao Pedro Petro (1 variety of species M. esculenta Crantz) were studied in vitro and further evaluated using the western blot technique. Three steroid compounds, namely β-sitosterol (1), Campesterol (2), and Cholesterol (3), were obtained from the n-hexane extract of fresh Cassava tubers (Manihot esculenta Crantz). The chemical structures of compounds 1 - 3 were determined through various spectroscopic techniques such as HR-TOFMS, and NMR (1H, 13C, DEPT 135 °, HMQC, HMBC, 1H-1H COSY), along with a comparison to previously reported spectral data. Additionally, the apoptotic signaling pathway was investigated using RT-qPCR and western blot analysis. Among the 3 compounds, Campesterol (2) exhibited the highest IC50 value and demonstrated significant inhibition of B16-F10 cell proliferation by inducing apoptosis through caspase-3 activation. In conclusion, our study is the first to show that steroid compounds isolated from M. esculenta have activity against B16-F10 cells. This provides insight that steroids have the potential as chemopreventive agents to treat melanoma skin cancer. HIGHLIGHTS Three steroid compounds, namely β-sitosterol, campesterol, and cholesterol, were isolated from the n-hexane extract of fresh cassava tubers (Manihot esculenta Crantz) and campesterol exhibited the highest cytotoxic activity against B16-F10 melanoma cells, with an IC50 value of 160.4 µg/mL Campesterol induced apoptosis in B16-F10 melanoma cells through caspase-3 activation Treatment with campesterol led to noticeable alterations in cell morphology, including changes in shape, size, and other visible characteristics, further supporting its cytotoxic effects on melanoma cells The research's novelty lies in its exploration of previously unreported steroid compounds from cassava tubers, particularly campesterol, and their cytotoxic effects on melanoma cells, along with insights into the underlying mechanisms of action These findings contribute to the growing body of knowledge on natural compounds with potential therapeutic applications in cancer treatment GRAPHICAL ABSTRACT

Design and Performance Evaluation of an Air Flow Meter for Drying Cassava Chips

Drying is an important unit operation in the processing of fresh cassava tubers into cassava chips. An air flow meter is a device that measure airflow. Airflow meter and direction sensing are importance in many fields, including the monitoring on vehicle engine performance. The airflow meter for cassava chips measures how much air is flowing through the cassava chips. There are many reasons and ways to measure airflow, this technical method of explores the use of air flow meter to measure cassava chips in order to ensure the proper airflow to dry the cassava chip, which will improve the value chain of cassava processing. This research work focused on the design and performance evaluation of an airflow meter for drying cassava chips. The air flow meter was made from locally available materials and it consists of a blower, pressure, sensor, temperature sensor, heating chamber which was used to carry out several tests on cassava chips. From the test conducted during drying operation, at a temperature of 900c for a 372g of cassava chips, it takes a period of 180 minutes (3hours) with an airflow of 133m3/sec to dry it to a safe moisture content. At temperature 1100c for 617g of cassava chips, it takes a period of 240 minutes (4hours) with an airflow of 209m3/sec to dry it to safe moisture content. The efficiencies of the drying mechanism and measuring airflow device are 70% and 65% respectively. The sample dried with airflow meter still retain their white colours, thus indicating no mould growth.

Effective measurement of starch and dry matter content in fresh cassava tubers using interactance Vis/NIR spectra

The quality of cassava in this study was indexed according to the starch content (SC) and dry matter content (DM). The NIR spectroscopy had the potential to measure changes in SC and DM of field-grown cassava. However, due to the non-homogenous nature of cassava root and its unpredictable shape, measuring it using NIR spectroscopy presents a challenge. Therefore, the model developed from different scanning method (horizontal and vertical lines) and surface (original surface, removed brownish outer layer, and fresh surface) were compared. To demonstrate that the model performance could improve by using a few significant wavelengths, its accuracy was compared using either the full wavelength or individual wavelengths selected by bootstrapping soft shrinkage analysis (BOSS) and competitive adaptive reweighted sampling (CARS) methods. Finally, the impact of physical properties (sample sections, peel thickness, varieties, and ages) on model error were determined. The prediction accuracy was found to depend on the scanning method. Since the model developed using horizontal spectra obviously obtained highest accuracy. The difference in surface had no effect on accuracy based on the horizontal spectra. Therefore, original surface scanning was chosen due to its non-destructive performance. The prediction model using the CARS-PLSR method was considered appropriate for predicting SC and BOSS-PLSR for predicting DM, providing R2cal, r2val, SEP, and ratio of prediction to standard deviation (RPD) of 0.69, 0.66, 3.18%, and 1.81, respectively; and 0.63, 0.54, 4.15%, and 1.50, respectively. In addition, the sample section, variety and peel thickness of the cassava root were not effected in the error of prediction.

Achieving prediction of starch in cassava (Manihot esculenta Crantz) by data fusion of Vis-NIR and Mid-NIR spectroscopy via machine learning

Cassava is an important crop for both the food and bio-energy industries, serving as a primary carbohydrate source and a staple food. Knowledge of the starch content (SC) is a key parameter index its quality. Non-destructive measurement of SC is needed to track the same tubers to study behaviours of SC accumulation in cassava tubers, which benefit for breeders in discovering a good variety and farmer to indicating harvesting period. This paper involves the prediction of cassava tuber starch content (SC) using multiple near infrared (NIR) spectrometers, aiming to measure SC in fresh cassava tuber. This study applies both portable NIR spectrometers at 570–1031 nm and 860 – 1760 nm. The best results of the model which developed provided R2p and RPD were 0.69 and 1.80 for VIS-NIR region. Meanwhile, the Mid-NIR region provided poor performance with R2p and RPD of 0.46 and 1.36, respectively. Therefore, this study aims to assess whether it was better for predicting SC if the model was developed using combined selected significant wavelength from both VIS-NIR and Mid-NIR regions using machine learning. Genetics algorithm (GA) and variables important projection (VIP) were used for selecting significant wavelength. Selected wavelengths were combined and then generate calibration models via machine learning (ML). The results of the SC model developed using NIR spectra from selected wavelength with SV regression method had the highest performance, with R2c and RMSEc of 0.88 and 1.28%. Meanwhile, the R2p, RMSEp, and RPD of 0.74, 1.86% and 1.97, respectively. Then, the best calibration model was used to measure the unknown sample which corrected from a different harvest season. The external test set provided R2p, RMSEp were 0.88 and 1.38%. The results indicate that combination of NIR with different region can achieve.

Evaluation of a Modified Multipurpose Cassava Processing Machine for Size Reduction

The production cassava ( Manihot esculenta ) is considered an important alternative to reduction in food scarcity around the world. In Kenya, it is rapidly gaining prominence due to the declining production of staple foods, especially maize and wheat. Though still considered a poor man’s food, the usage of cassava has greatly diversified in terms of both industrial and domestic applications. This coupled with the introduction of improved varieties and better farming options calls for innovative ways of handling the increasing volumes of fresh cassava tubers to minimize post-harvest losses. One of the important postharvest processes is size reduction which is achieved by either chipping or grating. Improved production methods alone are not adequate to solve the issues of field losses in cassava production. Factors affecting the efficiency of size reduction operation include operator experience, disc type, disc speed, cutting clearance and moisture content. Conventionally, this has been done manually but due to the inherent problems, use of machines is being encouraged through the development and adoption of chipping/grating machines. In this study the machine developed was dual powered and allowed conversion from a chipper to grater and vice versa as need be. It has a capacity of 162.15kg/h and 81.62 kg/h when chipping and grating respectively. The chipping process consumed less power averaging 0.0034kW/kg compared to 0.0075 kW/kg used in the grating and these chips dried faster than manually worked cassava. Keywords: Cassava, post-harvest, chipping, grating, dual power DOI: 10.7176/JBAH/13-8-03 Publication date: May 31 st 2023

Functional Compound Changes during Postharvest Physiological Deterioration of Cassava Tuber

Reducing the economic value of the cassava tuber crop, thereby Postharvest Physiological Deterioration (PPD) is the major problem in cassava that renders the tuber unmarketable. After harvest of cassava tuber causing fluorescence in the storage parenchyma was observed, because changes in metabolic compound mainly responsible for the fluorescence. Its content peaks within 24 hours of injury and prior to the development of the visual symptoms of physiological deterioration. The present study of Fourier infrared transform spectroscopy (FTIR) was performed with CI 850, YTP 1, H740/92 and H226 cassava genotypes to identify the functional compound changes during Postharvest Physiological Deterioration. FTIR spectroscopy is a technique based on the determination of the interaction between infrared (IR) radiation and a sample. The present study revealed that the extracts of fresh cassava tuber and stored tubers of different cassava genotypes, has potential to produce bioactive functional compounds like hydrocarbons, oxygen compounds, nitrogen containing compounds, isocyanates, thiocyanide, cyanide, isothiocyanates, oxidized nitrogen functions, sulfur compounds, phosphorous and amides but their quantity was differently in cassava genotypes which correlate with reinforcement of tolerance to PPD under storage condition.

Influence of Edible Coating from Sesame and Moringa Seed Oil on Nutritional Properties of Cassava

Cassava roots are perishable commodities that cannot be stored for a very long period of time after harvest in ordinary conditions. During storage, the quality may be very different from utilization quality. Thus, this experimental lot was designed to investigate the influence of the oil coating on the nutritional quality of fresh cassava tubers under ambient storage conditions. Three different treatments comprising of root crops (Untreated), root crop coated with sesame oil (1: 1 water/oil), root crop coated with moringa oil (1:1 water/ oil). The sample coated with sesame seed oil showed a more favourable result. Moisture ranges from 67.60-74.52% for both treatment, titratable acidity ranged from 0.15-0.33%, ash content value ranged from 0.91-1.61% and crude fibre ranged from 0.91-2.05% for both treatments. The obtained results indicated that the treatment with oil (sesame and moringa) under storage showed a significant (p˂0.05) difference in the nutritional quality value of the stored cassava roots. It also plays a role in prolonging the shelf life of the cassava and delaying rotting.

Achieving robustness across different ages and cultivars for an NIRS-PLSR model of fresh cassava root starch and dry matter content

• Starch content and dry matter content models for fresh cassava tubers were optimized. • NIR spectroscopy was used to predict starch and dry matter content in fresh cassava roots under field conditions. • Spectral variable selection was carried out using SPA and GA methods. • The starch and dry matter content was evaluated under field conditions for breeding purposes. • New spectral processing methods improved the model’s accuracy. This study used a portable near-infrared (NIR) spectrometer at wavelengths of 570–1031 nm to evaluate starch content (SC) and dry matter content (DMC) in fresh cassava tubers. An improved model was developed for the prediction of cassava tuber quality. The cassava samples were taken from four main varieties: CMR38-125-77, KU50, RY11, and RY9. The samples were obtained 4–12 months after planting (MAP). Partial least squares (PLR) regression was combined with different variable selection methods and spectral pre-treatment. Their accuracies were then compared. Variable selection methods included the successive projections algorithm (SPA) and the genetic algorithm (GA). The NIR spectra were obtained in the interactance mode under field conditions. The GA wavelengths combined with sequential pre-processing by orthogonalization (SPORT) pre-processing provided the optimum model for predicting both the SC and the DMC of cassava. The R 2 p, RMSEp, and RPD of SC were 0.91, 1.76%, and 3.26, respectively, and those of DMC were 0.75, 2.00%, and 2.00, respectively. The most effective model was tested against unknown samples of newly developed varieties obtained from different harvest seasons, yielding RMSEp and bias values of 2.37% and −9.178 × 10 -6 %, respectively, for SC. For DMC, the RMSEp and bias values were 2.67% and 4.16 × 10 -14 %, respectively. The results suggest that the calibration model could be used to monitor the internal quality of cassava tubers in the field. The variety, age, position, and section of the tubers had a slight influence on the prediction performance; however, the prediction accuracy was acceptable for in-field applications. The in-field portable NIR spectrometer could become a new tool for breeders, saving time and costs. Breeders could evaluate SC without destroying the cassava roots or stalks and could correct and inspect the behaviour of the SC and DMC accumulation.

DIELECTRIC PROPERTIES OF FRESH CASSAVA TUBER AT 2-2.90 GHZ MICROWAVE FREQUENCY

Rapid quantification of starch present in fresh cassava tuber by electronic means requires a conductivity work at various points of the tuber. The dielectric parameters of different samples of cassava tuber (Manihot esculenta L.) at the S-band of the microwave frequencies were determined. Tubers of cassava varieties of CTCRI, H-226, H-97, Sree Harsha, Sree Prabha, Sree Rekha, Sree Jaya, Sree Sahya, Sree Vijaya, Sree Prakash, Sree Visakham and H-165 were subjected to the cavity perturbation technique. The range of S-band microwave frequency tested were 2247, 2440, 2684 and 2970 MHz. Tubers of the variety H-226 had significantly lower conductivity value was 0.02s/m and the variety H-165, 1.49s/m and are significantly different. The dielectric constant (real part) of tubers of the varieties, H-165 and H-226 were 34.82 and 14.97 respectively and were significantly different. The proximal part of the tuber had the lowest level of conductivity followed by the middle portion and then the distal portion being 0.60s/m, 0.65s/m and 0.69s/ m respectively. The dielectric constant decreases steadily with increase in frequency between 2.00-2.90GHz range for fresh cassava tubers and the dielectric loss factor follows the same pattern. The moisture content of different varieties of fresh cassava tuber, H-226, H-97, Sree Harsha, Sree Prabha, Sree Rekha, Sree Jaya, Sree Sahya, Sree Vijaya, Sree Prakash, Sree Visakham and H-165 ranged between 44.52% and 58.66% as analysed using the moisture analyser at 80 °C. The starch content values estimated by the chemical method for all the varieties of fresh tuber ranged between 20.78% and 35.94%. The difference in starch content of tuber between the proximal and the middle region was found to be 3% and that of the middle and distal region was found to be 2%. The conductivity values of fresh cassava tuber can be used for the development of a starch indicator based on moisture content.

EFFECT OF SELECTED MINIMAL PROCESSING TECHNIQUES IN CASSAVA TUBERS

Minimal Processing is the technique to process a fruit or vegetable commodity to a minimum level for maximum shelf life while maintaining its freshness nearly intact. The rapid perishability of fresh cassava tuber imposes a limitation in its marketing and consumption. In view of this, fresh cassava tubers of variety,’ Sree Vijaya’ were subjected to minimal processing techniques of steaming, dipping in hot water (98 o C), dipping in hot oil (190 o C) and microwave oven treatments. Steaming, dipping in hot water as well as the microwave oven treatments were conducted for 1,2,3,4 and 5 min time intervals using peeled cassava chips of 2,4,6,8 and 10 mm thickness. The time of treatment for dipping in hot oil, however, was resricted to 15,30 and 45 seconds. Quality factors such as crumbling, cracking, odour and surface gelatinization, were observed. The fresh sample served as the control. Shelf life studies were done for tubers packed in 28µ thick polythene bags of 21 × 15 cm size at ambient (30 o C) and refrigerated (5 o C) condition, by regular visual observations for any microbial attack. Significant difference in starch was found in case of 2,4 6 and 8 mm thick chips dipped in hot water. The weight loss parameter was statistically analysed at 5% level of significance using Anova for all the 4 techniques. Micro wave oven treatment of fresh cassava chip samples is observed to be the most effective minimal processing technique. The shelf life of the product could be enhanced to 3 days, compared to 2 days in low temperature storage for the control, and the product also has maximum resemblance with the fresh chips in its quality attributes.

The Effect of Melanthera Scandens and Mimosa Pudica on Fungi Causing Postharvest Deterioration of Cassava Root Tubers

Fresh cassava (<i>Manihot esculenta</i>) tubers unlike most other tubers of root crops are highly perishable. This study, therefore, investigated the antifungal activities of ethanol and hot water extract of <i>Melanthera scandens</i> (vine) and <i>Mimosa pudica</i> (touch me not) on rot fungi of cassava. Rotten cassava tuber samples were inoculated into Potato Dextrose Agar (PDA) for isolation of rot fungi causing postharvest deterioration of cassava tubers. The fungi obtained were identified using macroscopic and microscopic characteristics. The establishment of the pathogenicity of the fungal isolates was carried out by inoculating freshly harvested cassava tubers with the isolated fungi. The ethanol and hot water extract of the selected plants were tested against the isolated fungi both <i>in vitro and in vivo</i>. The isolates were identified as <i>Aspergillus niger, Aspergillus flavus, Penicillium notatum, Penicillium sp, and Fusarium verticillioides. A. flavus</i> being the most virulent with a percentage in severity of (27.15) on day 7 as compared with <i>Aspergillus niger, Fusarium verticillioides, Penicillium sp, and Penicillium notatum</i> which had (25.22, 17.17, 15.76 and 14.71) respectively. In the <i>in vitro</i> test the plants exhibited a high degree of fungicidal activity by inhibiting the mycelia growth of the rot fungi and <i>Mimosa pudica</i> was more effective in the suppression of fungal growth than <i>Melanthera scandens</i>. In the <i>in vivo</i> test there was a higher percentage reduction in diameter of rot when the plant extract was applied after twenty four hours of microbial inoculation directly to the cassava tuber. The extracts of <i>Melanthera scandens</i> and <i>Mimosa pudica</i> can therefore be used as a bio fungicide to extend the shelf-life of freshly harvested cassava tubers.

BIOETHANOL POTENTIAL FROM WHOLE PARTS OF CASSAVA PLANT IN INDONESIA

Cassava is a promising bioethanol feedstock as all parts of cassava plant including its tuber, stem, leaves, along with processing waste such as peel and bagasse can be used in bioethanol production. However, bioethanol potential from the whole parts of cassava plant is not yet summarized. This research reviewed and calculated the average bioethanol yield from each part of the cassava plant, and calculated bioethanol potential from the whole parts of cassava plant, especially in Indonesia. Fresh cassava tuber, fresh stem, fresh leaves, fresh peel, and dry bagasse are found to have average bioethanol yield of 180 L/ton, 155 L/ton, 75 L/ton, 160 L/ton, and 390 L/ton, respectively. If the whole cassava plant along with its processing waste is utilized for bioethanol production, cassava plants that produce a ton of fresh cassava tuber can yield 400 L bioethanol. With a scenario of total area harvested 700,000 ha and cassava productivity of 22.5 tonnes/ha/year, bioethanol potential from whole cassava plant and its processing waste in Indonesia is 6.3 billion L/year. However, using all the cassava plant for bioethanol production is impractical, considering other utilization of cassava. The bioethanol potential from whole parts of cassava plant after considering other use of plant becomes 2.9 billion L/year. Even when the cassava tuber is used for other utilization, bioethanol from unused cassava stem, leaves, peel, and bagasse is still significant and worth considering. Keywords: bioethanol, cassava plant, waste

Effect of feeding different levels of fermented and unfermented cassava tuber meals on performance of broilers

Studies were conducted to determine the relative effects of fermented and unfermented sun-dried cassava tuber meals as source of energy in broiler diets. A batch of fresh bitter cassava tubers (TMS 30572 variety) was cut into pieces, dried in the sun and milled (UFC). Another batch was cut into pieces, fermented in water for 4 days, dried in the sun and milled (FC). Both fresh cassava tubers and processed meals were analyzed for proximate composition and cyanide contents. In the first experiment, the meals were used to make 7 iso-nitrogenous broiler starter diets such that diet I (the control) contained maize as source of energy while in diets 2, 3 and 4, 50%, 75% and 100% of the maize in the control diet was replaced with UFC and in diets 5, 6 and 7, the maize was similarly replaced with FC. Each diet was fed to a group of 24 broiler chicks replicated into 2 from / week old to 5 weeks old. In the second experiment, the meals were used to make 7 iso-nitrogenous broiler finisher diets, using replacement levels as in the starter trial, and each diet fed to a group of 22 broiler chicks replicated into 2 from 5 weeks old to 9 weeks old. Fresh cassava tuber contained 0.44mg HCN/gm while unfermented and fermented meals contained 0.15mg HCN/gm and 0.08mg HCN gm, respectively. There were no significant differences (P&gt;0.05) in proximate composition of the three samples. In the starter trial, the group that received the diet in which 50% of maize was replaced with UFC or FC compared favourably with the control in performance (P&gt;0.05). Although at 100% replacement level, both UFC and FC significantly depressed performance of the chicks, UFC resulted in severe stunted growth and ruffled feathers of the chicks. In the broiler finisher trial, replacement of maize up to 75% with FC produced no adverse effect (P&gt;0.05) whereas at that level, UFC significantly depressed performance (P&gt;0.05).

Effect of Tillage Practices on Selected Engineering Properties of Cassava (&lt;i&gt;Manihot esculenta&lt;/i&gt;) Tubers

The main objective of this study was to determine the influence of tillage practices on selected engineering properties of cassava tubers. Two field tests were conducted between May 2014 to April 2015 and May 2015 to April 2016. Eight tillage practices utilized for the experiment were coded as; Ploughing + Harrowing (A), Ploughing + Harrowing + Ridging (B), Manual Ridging (C), Minimum Tillage (D), Ploughing + Harrowing + Manual Digging to a depth of 30 cm + Sawdust of 10 cm depth set at the base (E), Ploughing + Harrowing + Ridging + Sawdust of 10 cm depth set at the base (F), Manual Ridging + Sawdust of 10 cm depth put at the base (G) and Manual Digging to a depth of 30 cm + Sawdust of 10 cm depth put at the base (H). TMS 0581 improved cassava variety and two fertilizer rates 622.50 kg/ha and control were used. Randomized Complete Block Design was used. The experiment was 8x2x1 factorial combinations in split-split plot design with three replications. The effect of different treatments on selected engineering properties of cassava tubers were determined. The results showed that Ploughing + Harrowing (A) tillage practice was significantly different from other tillage practices and gave the most suitable selected engineering properties of size 10.53±0.64c cm, surface area 371.15±45.53bc cm2, sphericity 39.26±1.74a cm, roundness 21.40±3.29ab , bulk mass 21.43h kg, coefficient of static friction 2.73±0.06abc, compressive strain at break of 2.16±0.03e mm/mm, compressive load at break of 11698.90±178.71f N, compressive stress at break of 2.72±0.04d MPa, energy at break of 191.62±2.93e J, modulus automatic of 1.89±0.031c MPa, followed by F, G, D, C, E, H and B tillage practices respectively. The study had provided some engineering properties for engineers to develop efficient agricultural machines for handling and processing of fresh cassava tubers.&#x0D; Keywords: Evaluation, influence, tillage practices, engineering properties, cassava tubers.

UJI KANDUNGAN PROTEIN PADA BEBERAPA VARIETAS UMBI UBI KAYU ( Manihot esculenta Crantz) YANG DIHASILKAN DI DESA RANDOTONDA, KECAMATAN ENDE, KABUPATEN ENDE

This study aims to determine the protein content found in all three cassava varieties. The cassava varieties produced in Randotonda Village, namely the cassava variety, the variety of cassava Ai land, and the flour cassava varieties. Test the protein content of several cassava varieties with varied harvest ages using the Kjedhal method. Cassava varieties of Tanah ai varieties with an harvest age of 8 months, cassava tubers, 10 months old verietas, and cassava flour 12 months old.The results showed that the three types of fresh cassava tubers of White variety were 1.59%, Tanah Ai cassava varieties were 1.48% and Wheatwood sweet potato varieties were 1.18%. This is because the White yam variety is 8 months old, while the 10-month AI variety and the Wheat variety are 12 months (1Year).

In-field measurement of starch content of cassava tubers using handheld vis-near infrared spectroscopy implemented for breeding programmes

This paper involves the prediction of cassava tuber starch content (SC) using near-infrared (NIR) spectroscopy, aiming to follow the change of SC in individual tubers utilised for a breeding programme. This study applies a portable NIR spectrometer at wavelengths of 570–1031 nm in the evaluation of SC in fresh cassava tubers. The prediction models are established using partial least squares (PLS) regression with NIR spectra obtained in the interactance mode. The effective model was developed from the wavelength region of 600–1000 nm with spectral pre-processing of the second derivative, giving the coefficient of determination of prediction set (r2) and root mean square error of prediction (RMSEP) of 0.62 and 2.21%, respectively. The effect of tuber section (including head, middle and tail) on the performance of the SC model was investigated. The individual head, middle and tail models were acceptable for screening. However, the performances of the combined model (which is the model developed a mix of all individual section samples) and the individual section model were not significantly different. Therefore, the combined model was suitable in real application because of the ease of in-field scanning. The result demonstrates that the SCs of cassava tubers can be measured by a NIR spectroscopy method. Furthermore, it can be used as an alternative tool which is appropriate for breeders to use to follow the behaviour of SC during breeding.

Field measurements and statistical analysis of perforated grating surfaces for grating fresh cassava into mash in Ghana

Processing of cassava into mash requires grating of fresh cassava tubers through the abrasive action of the grating surfaces of cassava graters that grind against the cassava and transforms it into mash. Over the years, improved cassava graters have been designed and made available on the market. In spite of improvements in design, there are no standards for the manufacture of grating surfaces and this affects interchangeability of the product. Mechanised grating of fresh cassava into mash contributes to reduce postharvest losses of cassava, increase its shelf life and improve food security. However, majority of the cassava grating surfaces are poorly made with substandard measurements that affect the desired particle size of mash for gari, a staple food for millions of people in West Africa. This study assessed cassava grating surfaces focusing on the abrasive elements (tooth diameter and inter-tooth spacing). Qualitative data were gathered from local metal fabricators and female gari processors in separate focus group discussions. The purpose was to gather the narratives underlying the issues being studied so as to complement and enrich the quantitative data. 112 tooth diameters and 112 inter-tooth spacing of perforated cassava grating surfaces were randomly measured in 16 different study areas in 3 regions of Ghana, namely Western, Central and Ashanti. Results from the qualitative data showed that grating of cassava was done repeatedly (about 2-3 times) before reaching the desired particle size of mash for gari. Most customers desire grating surfaces that ensure effective contact between the cassava and the metal grating surface to reduce grating time. Results from the field measurements showed high variation in existing tooth diameters (min=1.80, max=4.50 mm) and inter-tooth spacings (min=3.50, max=12.00 mm) that resulted in non-uniform particle size of cassava mash. Using statistical analysis, tooth diameters (min=3.18, max=3.42mm) and inter-tooth spacings (min=7.12, max=7.78mm) were determined at 95% confidence interval. For practical purposes, tooth diameter of 3 mm and inter-tooth spacing of 8 mm are recommended. The availability of such data will contribute significantly to standardise perforated cassava grating surfaces to achieve product interchangeability and desired quality of grated mash for gari. This will contribute to improve the manufacture of cassava graters and sustainable gari processing business in Ghana and Africa. Keywords: Fresh cassava, cassava grating surface, gari, food quality, Ghana

Effectiveness of Traditional Processing Techniques in Reducing Cyanide Levels in Selected Cassava Varieties in Zombo District, Uganda

The root tubers of cassava (Manihot esculenta Crantz) contain varying amounts of cyanogenic glucosides which liberate toxic hydrogen cyanide with the resultant effect of poisoning especially the highly cyanogenic cultivars. These include some of the local and improved cassava varieties grown in Zombo district, Uganda among others. Therefore, this study explored the effectiveness of some traditional processing techniques used singly and in combination to reduce cyanide levels in highly toxic root tubers of selected local (Nyar-anderiano, Nyar-papoga, Nyar-udota, Nyar-pamitu, Bisimwenge, Nyar-matia) and improved (NASE 3, NASE 9, NASE 14, NASE 19, TME 14 and TME 204) cassava varieties grown in Zombo District, Uganda. The processed and the fresh cassava tubers were analysed for Hydrogen cyanide (HCN) by the standard titration method. The results indicated that heap fermentation followed by sun-drying reduced the cyanide levels in all the selected improved varieties to WHO safe levels for consumption (below 10mg/kg) in the dried chips. Mixed processing methods combining soaking, fermentation and sun-drying reduced the cyanide concentrations in the local varieties (Nyar-udota, Nyar-anderiano) and improved variety (NASE 19) to World Health Organisation (WHO) safe levels. None of the processing techniques used singly reduced the HCN levels in the root tubers of the selected cassava varieties to safe levels. Hence mixed strategies combining several traditional cassava processing techniques should be adopted to detoxify the selected cassava varieties of cyanogens. The local cassava varieties (Bisimwenge, Nya-matia, Nya-pamitu, Nya-papoga) would require modifications of the combined traditional processing techniques or other more complex processes to detoxify them of HCN before human consumption.

Time Course of Starch Biosynthesis Enzymes Activity and Root Tuber Starch of Four Cassava Cultivars

To understand the accumulation rule of cassava root tuber starch, the amylose, amylopectin and total starch content of fresh root tuber, the enzyme activities of sucrose synthase (SuS, EC 2.4.1.13) and sucrose phosphate synthase (SPS, EC 2.4.1.14) of leaves, the enzyme activities of ADP-glucose pyrophosphorylase (AGPase, EC 2.7.7.27), soluble starch synthase (SSS, EC 2.4.1.21) and starch branching enzyme (SBE, EC. 2.4.1.18) of tubers were assessed by using cultivars SC201, SC205, GR891 and GR911 leaves and root tubers during their growth period, respectively. The results as follows: the enzyme activity of leaf SPS and the synthesis direction of SuS showed the highest at August, 2010, however the enzyme activity of the decomposing direction of SuS formed parabolic curve; the enzyme activity of tuber AGPase showed an increased then decreased single peak curve, the enzyme activity of tuber SSS oscillating decreased, while the enzyme activity of SBE was relatively stable; the amylose, amylopectin and total starch contents of fresh cassava tuber were all gradually increased along with the growth period. This research would enrich our knowledge of the time course of amylose, amylopectin and total starch contents of fresh cassava tuber, and above related enzyme activities.