57 research outputs found
A comparative study of the physicochemical properties of starches from root, tuber and cereal crops
Some properties of starches from cassava, potato and sweet potato were compared with cereal starches from maize, wheat, millet and sorghum. The aim was to determine the properties of tuber and root crop starches and compare them with cereal starches in addition to unravelling the potential of commonly grown sorghum and millet climate resilient crops as cheap and sustainable sources of starch. Significant variations were observed for amylose content and solution properties of starches, where blue values for amylose ranged from 0.355 in potato to 0.476 in cassava, but were averagely low in cereal starches. Amylose leaching increased with temperature with the highest value (0.432) in cassava at 80°C compared with cereal starches (average 0.361). Starch amylosis increased with time of hydrolysis and was highest (>16%) for millet and sorghum and least for potato (<8.5% average). Average swelling power at 80°C was high for cassava (8.58 g/g) and potato (8.44 g/g) compared with sweet potato (6.88 g/g) and low among cereal starches (5.17 g/g). Similarly, starch solubility was low in potato (0.77 g/g) and sweet potato (0.577 g/g) compared with cassava (1.23 g/g). The paste clarity was also high for cassava (48.32%) and potato (42.16%) and least for sweet potato derived starches (23.22%) and all the cereal starches (14.97%). These properties demonstrate the untapped potential of cassava and tuber based starches for use in food and non-food applications previously dominated by cereal starches.Key words: Tuber starch, root crop starches, cereal starches, amylose, amylosis
Influence of spectral properties on cassava leaf development and metabolism
Cassava’s importance as a food security crop in Sub Saharan Africa will be enhanced by its special traits such as tolerance to drought and high yields under hydrothermal stress. Some of the special traits which include the light reflective and absorptive properties of the leaves that depend on the surface characteristics of the leaves, are variety dependent and may influence the plants’ reaction to light; hence, its photosynthetic capacity. We investigated the differences in the leaf spectral properties in different cassava varieties and related them to leaf biochemical properties using 20 cassava varieties established in a randomized complete block design in Kasese, western Uganda. Time dependent changes in leaf spectral characteristics were studied using Digimizer software and related to changes in sugar and pigment properties. Changes in the amount of reflected light were observed for the three main wavelengths used by plants (blue, green and red) with the blue being the most preferred. Total soluble free sugars exhibited a diurnal pattern from lower values (0.07 mg/g) after the dark period to higher values (0.313 mg/g) as the day progressed and was different from those of translocatable sugars such as sucrose. Chlorophyll a exhibited a curved pattern in all varieties increasing with increase in light intensity from 09:00 h (0.18 ug/g), peaking at 15:00 h (0.22 ug/g) and dropping down in concentration by 18:00 h (0.16 ug/g). Significant differences were observed in cassava varieties for the concentration of chlorophylls and carotenes. The results were obtained at a time of optimal growth conditions (four months after planting) and were used to classify these varieties into three broad groups showing that studies on spectral properties of leaves can still give a lot of insights in selection for stress tolerance under less optimal stress. The significant changes observed in the phenotype especially the foliar portion of the plant with the stay green and early recovering mechanisms of tolerance identified also tarried well with observed spectral differences. The results show that studies on plant spectral properties can be important in making inferences on the plants physiological and growth status.Keywords: Spectral properties, tolerance mechanisms, physiology, reflectance
Training report: capacity building in entrepreneurial and business skills for operationalizing fresh cassava roots packhouse.
This report describes the capacity building process and activities that were done to enhance the business and entrepreneurial skills of packhouse operators
Manual: fresh cassava roots handling for waxing and relative humidity storage
European Union and technical support of International Fund for Agricultural DevelopmentPeer Revie
Technical report: Postharvest Physiological Deterioration (PPD) tolerance of selected Ugandan cassava varieties. Extending the shelf-life of fresh cassava roots for increased incomes and postharvest losses reduction
The purpose of this study is to screen cassava varieties for their level of tolerance or susceptibility to Postharvest Physiological Deterioration (PPD). Specifically, it aims at collecting varieties of fresh cassava roots preferred by consumers in Ugandan. The study targets the two major fresh cassava supply axes, i.e., Masindi/Kiryandongo and Kyenjojo/Kabarole. Fresh cassava roots were screened for tolerance or susceptibility to PPD. The study also aims at determining the effect of pruning on the deterioration of cassava roots over time and the changes in root biochemistry during storage of both pruned and non-pruned cassava varieties
Training report: capacity building in agronomic practices, waxing and relative humidity storage technologies for shelf-life extension of fresh cassava roots.
This report describes the capacity building process and activities that were done to enable the value chain actors adopt and adapt the pre-and post-harvest practices, and waxing and high relative humidity storage technologies in order to run a successful business enterprise
Phenotypic diversity and chemical properties of pawpaw fruit quality in Ugandan germplasm
Pawpaw (Carica pawpaw L.) fruit production and utilisation have been on
the increase in Uganda. However, challenges related to identification
of phenotypes with inherent characteristics for improvement of fruit
shelf life have limited identification of better varieties. The
objective of this study was to evaluate the phenotypic diversity and
shelf life determinants of Uganda\u2019s pawpaw accessions and their
variations based on selected quality parameters. Nineteen accessions
were collected as seeds from different markets of Uganda, germinated
and planted in Namulonge-Wakiso district, central Uganda. The
accessions were significantly (P<0.05) variable in terms of fruit
weight parameters, with dry matter ranging from 14 - 19% and fruit
weight of up to 3.9 kg; while pulp weight was up to 3.2 kg per fruit.
Pulp firmness parameters were also significantly variable (P<0.05)
and highly correlated with shelf life of the fruit, which ranged from 7
- 13 days depending on the accession. Fruit pulp pH ranged from
4.4-5.6; while titratable acidity of the fruit ranged from 0.03-0.08%.
The accessions were clustered in four main clusters depending on the
fruit firmness properties, fruit shelf life, fruit weight, pH and
titratable acidity as definitive parameters. These accessions were
distinguished based on morphological parameters, and henceforth defined
for nutritional and economic uses. Accessions with high fruit firmness
(>5 kg F) such as 16/20\u2019 16/16, 16/17 and 18/1; and external
pulp thickness (>2 cm) such as 16/16, 16/17 and 18/1 had improved
fruit shelf life and are recommended for marketability and processing.La production et l\u2019utilisation de fruits de papaye (Carica pawpaw
L.) ont augment\ue9 en Ouganda. Cependant, les d\ue9fis li\ue9s
\ue0 l\u2019identification des ph\ue9notypes ayant des
caract\ue9ristiques inh\ue9rentes \ue0 l\u2019am\ue9lioration
de la dur\ue9e de conservation des fruits ont limit\ue9
l\u2019identification des meilleures vari\ue9t\ue9s.
L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer la
diversit\ue9 ph\ue9notypique et les d\ue9terminants de la
dur\ue9e de conservation des accessions de papaye en Ouganda et leurs
variations en fonction de certains param\ue8tres de qualit\ue9.
Dix-neuf accessions ont \ue9t\ue9 collect\ue9es sous forme de
semences sur diff\ue9rents march\ue9s de l\u2019Ouganda,
germ\ue9es et plant\ue9es dans le Namulonge, district de Wakiso,
\ue0 l\u2018 Ouganda centrale. Les accessions \ue9taient
significativement variables (P <0,05) en termes de param\ue8tres
de poids des fruits, avec une mati\ue8re s\ue8che allant de 14
\ue0 19% et un poids des fruits allant jusqu\u2019\ue0 3,9 kg;
tandis que le poids de la pulpe atteignait 3,2 kg par fruit. Les
param\ue8tres de fermet\ue9 de la pulpe \ue9taient \ue9galement
significativement variables (P <0,05) et fortement
corr\ue9l\ue9s \ue0 la dur\ue9e de conservation du fruit, qui
allait de 7 \ue0 13 jours selon l\u2019accession. Le pH de la pulpe
de fruit variait de 4,4 \ue0 5,6; tandis que l\u2019acidit\ue9
titrable du fruit variait de 0,03 \ue0 0,08%. Les accessions ont
\ue9t\ue9 regroup\ue9es en quatre groupes principaux selon les
propri\ue9t\ue9s de fermet\ue9 du fruit, la dur\ue9e de
conservation du fruit, le poids du fruit, le pH et l\u2019acidit\ue9
titrable comme param\ue8tres d\ue9finitifs. Ces accessions ont
\ue9t\ue9 distingu\ue9es sur la base de param\ue8tres
morphologiques, et d\ue9finies \ue0 la base des usages
nutritionnels et \ue9conomiques. Les accessions \ue0 forte
fermet\ue9 du fruit (> 5 kg F) telles que 16/20 \u201916/16,
16/17 et 18/1; et une \ue9paisseur de pulpe externe (> 2 cm) telle
que 16/16, 16/17 et 18/1 avaient une dur\ue9e de conservation
am\ue9lior\ue9e des fruits, et elles sont recommand\ue9es pour la
commercialisation et la transformation
Formulation of water and sanitation policies and strategies: experiences from Rwanda
This paper describes the process of formulation of Rwanda’s National Water Supply and Sanitation
Policies and Strategies, which were approved by the Cabinet in December 2016. The major steps in the
process included conceptualisation (preparation of a concept note and work plan); constitution of a
dedicated task force to oversee the process; engagement of international consultants; literature review
and information collection; preparation of background papers; stakeholders’ consultations; preparation
of draft polices and strategies; review and quality assurance by the sector working group and the task
force; consensus building; finalisation and approval. The process spanned almost two years and cost
approximately US$ 170,000, including the cost of external consultants and stakeholders’ consultations.
The case of Rwanda provides valuable lessons for other countries that plan to update their national
water and sanitation policies and strategies in view of changes in the context and emerging issues and to
ensure alignment with the SDGs
CASSAVA BROWN STREAK DISEASE EFFECTS ON LEAF METABOLITES AND PIGMENT ACCUMULATION
Cassava Brown Streak Disease (CBSD) is a threat to productivity and
product quality in East Africa. The objective of this study was to
understand the effect of CBSD on the primary photosynthetic apparatus
of cassava ( Manihot esculenta Crantz). Three cassava varieties with
varying levels of reaction to infection by CBSD were chosen and
subjected to field disease pressure. Disease progression and the
resulting effects on leaf morphology, metabolite and pigment
accumulation were assessed over a period of five months, beginning from
3 months after planting. Slight increments in leaf dry matter were
observed up to 4 MAP, and there after a drop was registered. A
significant (P<0.05) reduction in photosynthetic pigments occured
with a fall in the Chla:Chlb and Chla:Carotenoid ratio, indicative of
specific reductions in chlorophyll a (-80%) compared to Chlorophyll b
(-41 to -62%) and Carotenoid (-11 to -18%). Total reducing sugar and
starch content also dropped significantly (-30 and -60%, respectively),
much as NASE 14 maintained a relatively higher amount of carbohydrates.
Leaf protein levels were significantly reduced at a rate of 0.07 ug g-1
leaf per month in diseased treatments. Significant reductions in
primary metabolites show altered leaf photosynthetic and growth
metabolism, resulting into a compromised plant system that cannot
perform optimally.La Maladie Stri\ue9e Brune du Manioc (CBSD) constitue une menace pour
la productivit\ue9 et la qualit\ue9 des produits du manioc en
Afrique de l\u2019Est. L\u2019objectif de cette \ue9tude \ue9tait
de comprendre l\u2019effet de CBSD sur l\u2019appareil
photosynth\ue9tique primaire du manioc ( Manihot esculenta Crantz).
Trois vari\ue9t\ue9s de manioc poss\ue9dant differents niveaux de
r\ue9sistance \ue0 CBSD ont \ue9t\ue9 soumises \ue0 la
pression dans les conditions de plein champs. La progression de la
maladie et son effet sur la morphologie foliaire, les metabolites et
accumulations de pigments ont \ue9t\ue9 \ue9valu\ue9s sur une
p\ue9riode de cinq mois, \ue0 compter du troisi\ue8me mois
apr\ue8s semis. Il a \ue9t\ue9 observ\ue9e une l\ue9g\ue8re
augmentation de mati\ue8re s\ue8che foliaire jusqu\u2019\ue0 4
MAP, suivie d\u2019une chute. Une r\ue9duction significative
(P<0,05) des pigments photosynth\ue9tiques a \ue9t\ue9
observ\ue9e avec une chute dans le Chla:Chlb et Chla:ratio de
Carotenoide, indiquant des r\ue9ductions sp\ue9cifique sen
chlorophyllea (-80%) en comparaison avec la Chlorophylleb (-41 \ue0
-62%) et les Carotenoides (-11 \ue0 -18%). La r\ue9duction du sucre
et d\u2019amidona connu aussi une diminution significative (-30 et
-60%, respectivement), de m\ueame NASE 14 a maintenuun equantit\ue9
relativement\ue9 lev\ue9e d\u2019hydrates de carbone. Les niveaux
de proteines foliaires \ue9taient significativement r\ue9duits
\ue0 0,07 ug g-1 de feuille malade par mois. Des r\ue9ductions
significatives des metabolites primaires sont \ue0 l\u2019origne de
l\u2019alt\ue9ration du m\ue9tabolisme photosynth\ue9tique et de
croissance, resultant \ue0 cycle v\ue9g\ue9tatif compromis qui ne
peut permettre un d\ue9veloppement optimal de la plante
Technical Report: Market opportunities and value chain analysis of fresh cassava roots in Uganda.
European UnionInternational Fund for Agricultural Developmen
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