Effect of drying and storage on the content of provitamin A of orange fleshed sweet potato (Ipomoa batatas): direct sun radiations do not have significant impact

[Introduction] Sweetpotato is an important crop that is widely consumed in sub-Saharan Africa. Sun drying of sweetpotatoes is a traditional practice: after drying on rocks crushed or sliced dried sweetpotato are stored in granaries; re-hydrated and boiled to be eaten like fresh roots, or milled into flour to make porridge. Orange fleshed sweetpotato is being promoted in Africa to tackle vitamin A deficiency. There are inconsistent reports on the effect of sun-drying on pro-vitamin A retention. High losses have been reported which may be associated with the unsaturated instable provitamin A carotenoids easily degraded by light, oxygen and heat (Rodriguez Amaya 1997). This poster describes work to understand the effects of sun/solar drying and storage on pro-vitamin A retention

Impact of viral diseases and whiteflies on the yield and quality of cassava

Here we investigated the effect of the insect pest whitefly (Bemisia tabaci), cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) on cassava root yield and quality in two cropping seasons 2014–2015 and 2015–2016 on ten cassava varieties in Tanzania. ANOVA (sum of squares or SS) revealed that the time of planting (42.7%) and cassava variety (29.5%) had the largest effect on whitefly population. Not surprisingly, cassava varieties also had the highest effect (SS 39.8 to 70.4%) on both diseases and yield. An increase in whitefly population led to higher disease incidences and severity in 2015–2016 compared to 2014–2015. Some CBSD-resistant and tolerant cassava varieties like Namikonga and Kiroba, respectively, harboured high whitefly populations. The CMD, CBSD and whitefly-susceptible variety, Mreteta, showed highest yield losses of up to 60%, while the resistant variety NDL 2005/1471 had approximately 1% loss. Deployment of varieties resistant to both diseases and whitefly is thus necessary to safeguard cassava production and food security of vulnerable communities in the affected African countries

Relationship among the carotenoid content, dry matter content and sensory attributes of sweet potato

The sensory characteristics of biofortified sweet potato in Africa were explored over a wide range of carotenoid (0.4–72.5 μg/g fresh weight) and dry matter contents (26.8–39.4%). The logarithm of the total carotenoid content was correlated with the dry matter content (declining by 1.2% with each doubling of the carotenoid content) and a wide range of sensory characteristics that involve visual, odour, taste and textural characteristics. Multiple linear regression models were developed. The logarithmic relationship of colour to the carotenoid concentration means that those varieties with a relatively low carotenoid content may appear to be of similar intensity to those with a much higher and hence nutritionally beneficial carotenoid content

Effect of pretreatments for retaining total carotenoids in dried and stored orange-fleshed-sweet potato chips

Various dipping pretreatments have been investigated for orange-fleshed sweet potato (OFSP) to retain carotenoids after drying and subsequent storage. Effects of blanching, sodium metabisulfite (0.5 or 1%), acids (ascorbic acid [1%] or citric acid [0.5%]) or salt (1%), either singly or as mixtures, were tested on dried OFSP chips that were stored for up to 6 months in ambient conditions. Overall, there was a positive effect of dipping on total carotenoid content after drying compared with control (P < 0.05). A slight improvement in carotenoid content was observed during the first month of storage with ascorbic acid, sodium metabisulfite, and mixtures of sodium metabisulfite and citric acid, or ascorbic acid and salt pretreatments, but these higher levels were not maintained over longer storage periods (4–6 months). The general lack of improvement was believed to result from the leaching and degradation of the chemicals during storage

Retention and bioaccessibility of β-carotene in blended foods containing orange-fleshed sweet potato flour

The retention and bioaccessibility of β-carotene (BC) in blended foods made with part orange-fleshed sweet potato (OFSP) flour (30%) were examined. Chapatis and porridges were prepared by local processors under field conditions (FC) in Uganda (n=10). While the retention of all-trans-BC in porridges (69 to 93%) and chapatis (70 to 97%) varied between the processors, there was no overall difference between the two products and this was probably because of the variability in FC. BC retention in mandazis was similar to that of chapatis and porridges. Processing in FC significantly increased the amount of cis-isomers, in particular 13-cis-BC. The bioaccessibility of the BC as measured by their transfer into micelles was evaluated using an in vitro digestion procedure in various OFSP-derived products. After in vitro digestion, the percentage of micellarized all-trans-BC was greater in products cooked with oil: chapati (73%), mandazi (49%), as compared with the boiled ones: porridge (16%) and puréed from boiled root (10%). In all the products, the incorporation into micelles for 13-cis-BC was significantly higher to that of all-trans-BC. When taking in account the bioaccessibility of all-trans-BC and 13-cis-BC isomer, an edible portion of porridge (one mug), boiled root (half a root), mandazis (two) or chapati (one) could provide a significant part of the daily vitamin A requirements of a child under 6 years (respectively 20, 46, 75 or 100%). These data support the promotion/consumption of locally cooked OFSP food products to tackle vitamin A deficiency in sub-Saharan Africa

An international report on bacterial communities in esophageal squamous cell carcinoma

The incidence of esophageal squamous cell carcinoma (ESCC) is disproportionately high in the eastern corridor of Africa and parts of Asia. Emerging research has identified a potential association between poor oral health and ESCC. One possible link between poor oral health and ESCC involves the alteration of the microbiome. We performed an integrated analysis of four independent sequencing efforts of ESCC tumors from patients from high- and low-incidence regions of the world. Using whole genome sequencing (WGS) and RNA sequencing (RNAseq) of ESCC tumors from 61 patients in Tanzania, we identified a community of bacteria, including members of the genera Fusobacterium, Selenomonas, Prevotella, Streptococcus, Porphyromonas, Veillonella and Campylobacter, present at high abundance in ESCC tumors. We then characterized the microbiome of 238 ESCC tumor specimens collected in two additional independent sequencing efforts consisting of patients from other high-ESCC incidence regions (Tanzania, Malawi, Kenya, Iran, China). This analysis revealed similar ESCC-associated bacterial communities in these cancers. Because these genera are traditionally considered members of the oral microbiota, we next explored whether there was a relationship between the synchronous saliva and tumor microbiomes of ESCC patients in Tanzania. Comparative analyses revealed that paired saliva and tumor microbiomes were significantly similar with a specific enrichment of Fusobacterium and Prevotella in the tumor microbiome. Together, these data indicate that cancer-associated oral bacteria are associated with ESCC tumors at the time of diagnosis and support a model in which oral bacteria are present in high abundance in both saliva and tumors of some ESCC patients