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