Bussie Maziya-Dixon

Impact of Style of Processing on Retention and Bioaccessibility of β-Carotene in Cassava (Manihot esculanta, Crantz)

We previously demonstrated that the quantity of beta-carotene (BC) partitioning in mixed micelles during simulated small intestinal digestion, i.e., the bioaccessibility, of boiled cassava is highly correlated with the BC content of different cultivars. However, cassava is also traditionally prepared by fermentation and roasting. These different methods of preparation have the potential to affect both the retention and bioaccessibility of BC. Here, we first compared retention of BC in boiled cassava, gari (fermentation followed by roasting), and fufu (fermentation followed by sieving and cooking into a paste) prepared from roots of three cultivars. BC content in unprocessed cultivars ranged from 6-8 microg/g wet weight, with cis isomers accounting for approximately one-third of total BC. Apparent retention of BC was approximately 90% for boiled cassava and fufu. In contrast, roasting fermented cassava at 195 degrees C for 20 min to prepare gari decreased BC content by 90%. Retention was increased to 63% when temperature was decreased to 165 degrees C and roasting was limited to 10 min. Processing was also associated with a decline in all-trans-BC and concomitant increase in 13-cis-BC. The efficiency of micellarization of all-trans and cis isomers of BC during simulated digestion was 25-30% for boiled cassava and gari and independent of cultivar. However, micellarization of BC isomers during digestion of fufu was only 12-15% (P < 0.05). These differences in retention and bioaccessibility of BC from cassava products prepared according to traditional processing methods suggest that gari and fufu may provide less retinol activity equivalents than isocaloric intake of boiled cassava.

Genotypic differences in concentration and bioavailability of kernel iron in tropical maize varieties grown under field conditions

Abstract Iron deficiency is estimated to affect over one‐half the world population. Improving the nutritional quality of staple food crops through breeding for high bioavailable iron represents a sustainable and cost effective approach to alleviating iron malnutrition. Forty‐nine late maturing tropical elite maize varieties were grown in a lattice design with two replications in three locations representing three agroecologies in West and Central Africa to identify varieties with high levels of kernel‐Fe. Bioavailable iron was assessed for some varieties selected for high Fe concentration in kernel and improved agronomic traits using an in vitro digestion/Caco‐2 cell model. Significant differences in kernel‐Fe and ‐zinc concentration were observed among varieties (P < 0.001). Kernel‐Fe levels ranged from 16.8 to 24.4 mg kg−1, while kernel‐Zn levels ranged from 16.5 to 24.6 mg kg−1. Environment did not have a significant effect on kernel‐iron and ‐zinc levels, but genotype by environment (G × E) interaction was highly significant. The genetic component accounted for 12% of the total variation in kernel‐Fe and 29% for kernel‐Zn levels. Kernel‐Fe was positively correlated with kernel‐Zn (R 2 = 0.51, P < 0.0001). Significant differences in iron bioavailability were detected among selected Fe‐rich varieties grown at one location. Mean bioavailable Fe ranged between 30% below to 88% above the reference control variety. The results indicate that genetic differences exist in kernel‐Fe and ‐Zn concentrations and Fe bioavailability. These differences may be useful in biofortification intervention programs, but additional research is needed to determine the efficacy of iron‐rich maize varieties in alleviating iron deficiency in humans. #This research was supported by USDA-ARS/USAID and IITA.

Environmental stability of iron and zinc concentrations in grain of elite early-maturing tropical maize genotypes grown under field conditions

SUMMARY Assessment of the stability of micronutrients is important in breeding for the enhanced nutritional quality of staple food crops as a means to alleviate malnutrition. Twenty early-maturing elite tropical maize (Zea mays L.) genotypes were evaluated over 2 years at three locations representing three distinct agroecologies in West and Central Africa (WCA). The objectives were to analyse the pattern of genotyperenvironment interactions (GEI) and environmental stability of iron and zinc con- centrations in grain using the Additive Main Effects and Multiplicative Interaction (AMMI) stat- istical model. Results indicated that the effects of genotypes, environments and GEI were significant (P<0 . 05) for both micronutrients. The effect of GEI was about double the contribution of the genotypes for grain iron and more than double the effect of genotypes for grain zinc. Partitioning of GEI indicated that varietyrlocation was the dominant source of a significant amount of GEI for both micronutrients. Scores of the first two interaction principal component axes (IPCA1 and IPCA2) from the AMMI were significant and accounted for 0 . 68-0 . 75 of the pattern of GEI for both micronutrients. About half of the genotypes evaluated were stable for grain iron and zinc concen- tration over the set of environments. The AMMI model identified ACR98TZEMSR-W as the most stable genotype for grain iron and MAKA-SRBC5 was the most stable for grain zinc. However, the yellow genotype, AK94-DMR-ESR-Y was the most promising, with high and moderately stable concentrations of iron and zinc in the grain. Because it is yellow, with beta-carotene content and high concentrations of iron and zinc in the grain, it might significantly contribute to an improved intake of these micronutrients in populations who rely on maize for a major portion of their daily diet.

Chemical and functional properties of cassava starch, durum wheat semolina flour, and their blends.

High-quality cassava starch (HQCS) produced from high-yielding low-cyanide improved cassava variety, TMS 30572, was mixed with durum wheat semolina (DWS) on a replacement basis to produce flour samples containing 0, 20, 30, 50, 70, and 100% cassava starch. They were analyzed for chemical composition (proximate, amylose, free sugars, starch, wet gluten, and cyanide) and functional properties (pasting, swelling power, solubility, water absorption, water binding, starch damage, diastatic and α-amylase activity, dough mixing, and stability). Protein, carbohydrate, fat, and ash of flour samples ranged from 0.75–12.31%, 70.87–87.80%, 0.95–4.41%, and 0.12–0.83%, respectively. Cyanide levels in all the flour samples were less than 0.1 ppm. Amylose content varied between 19.49% for cassava and 28.19% for wheat, correlating significantly with protein (r = 0.95, P = 0.004) and ash contents (r = 0.92, P = 0.01) at 5%. DWS and HQCS had similar pasting temperatures (50.2–53°C), while other pasting properties increased with increasing levels of HQCS. Dough mixing stability of samples decreased with increasing levels of HQCS. All the flour samples had α-amylase activity greater than 200. Both HQCS and DWS compare favorably well in swelling power (7.80–9.01%); but the solubility of wheat starch doubled that of cassava. Starch damage varied between 3.3 and 7.2 AACC for semolina and starch, with the latter having higher absorption rate (97%), and the former, higher absorption speed (67 sec). Results obtained showed positive insight into cassava–wheat blend characteristics. Data thus generated provide additional opportunities of exploiting cassava utilization and hence boost its value–addition potentials for product development.

Household Utilization of Manioc (Manihot Esculenta Crantz) in Northern Mozambique

Mozambique is ranked ninth of top manioc (Manihot esculenta Crantz) producing countries in the world. Manioc roots are a staple to people living in the northern part of the country. Despite this, information on production, utilization, postharvest handling, and marketing is scarce. The purpose of this baseline study was to document selected information on manioc, from the production to marketing stage. To gather this information, 70 focus groups consisting of 1,724 participants purposely sampled from 10 districts were engaged in discussions using a questionnaire. The results show that manioc is the most important crop in terms of contribution to household food security and income in the region. Both men and women participate in the delivery of manioc production chain. Typically, 5 to 15 varieties identified by local language can be found on most farms in the study area. Manioc leaves and roots are the parts of the plant used as human food. Sun dried manioc roots are principally marketed within the locality of production by individual farmers. This baseline study suggests the need for location-targeted interventions as the farmers reported varied challenges along the manioc production chain.

Effects of husk and harvest time on carotenoid content and acceptability of roasted fresh cobs of orange maize hybrids

Vitamin A deficiency (VAD) is a major public health problem in many developing countries. Orange maize is preferred as green maize and consumed roasted on the cob, especially in Nigeria. This research work was to evaluate the effects of harvest time and husk on the carotenoid contents and sensory properties of roasted orange maize hybrids. The results showed that husk (roasting forms) and harvesting time had significant effects (P ≤ 0.001) on the carotenoids and the sensory properties. There was general increase in β-carotene and provitamin A (PVA) values as the harvesting time increases. The β-carotene and PVA values for roasted orange maize hybrids with husk were higher than those for roasted without husk. Hybrid 5 had the highest β-carotene concentration and PVA value at 27 days after pollination (DAP) and 34DAP when unprocessed and roasted without husk. This information can help researchers in choosing proper roasting methods to increase the retention of high levels of β-carotene and PVA in orange maize that can be delivered to consumers through nutrition education.

Physicochemical and bioactive properties of selected white yam (Dioscorea rotundata) varieties adapted to riverine areas of Nigeria

Yam (Dioscorea spp.) is a major food of cultural, economic and nutritional importance in Nigeria and throughout West Africa. In this sub-region, white yam (Dioscorea rotundata) is the most dominant and important species. This study is aimed at characterizing high yielding yam varieties of this species adapted to riverine areas and forest zones of Nigeria for physical and chemical characteristics. Eleven yam varieties collected from local farmers in the South-southern part of Nigeria were evaluated for their physicochemical characteristics, bioactive compounds (vitamin C, phytic acid and tannin), functional and pasting properties. Results indicated that there were significant varietal differences (P<0.05) among the parameters evaluated. The moisture contents of the investigated varieties ranged from 59.5 to 68.8%, ash content ranged from 1.39 to 2.93%, protein content from 1.96 to 4.90%, fat content from 0.356 to 3.39%, total free sugars from 1.05 to 7.02% and total starch from 33.9 to 75.7%. The bioactive content results show that vitamin C content ranged from 5.64 mg/100 g to 6.99 mg/100 g, phytate from 1.12 to 2.37% and tannin from 0.359 to 1.18 mg/g. The pasting properties results show that peak viscosity ranged from 215 to 470 RVU, trough viscosity from 198 to 385 RVU, breakdown viscosity from 8.71 to 84.5 RVU, final viscosity from 278 to 571 RVU, setback viscosity from 66.2 to 204 RVU; peak time ranged from 4.97 to 7.0 min and the pasting temperature from 61.7 to 62.6°C. This study shows that the physical and chemical characteristics of these high yield yam varieties were similar to those reported for most yam varieties in other parts of Nigeria and has a great potential as source of bioactive compounds and protein. Key words: Yam, Dioscorea rotundata, riverine areas, varieties.

Assessment of the potential industrial applications of commercial dried cassava products in Nigeria

Variations in the functional and pasting properties of four groups of commercial dried cassava product in Nigeria were evaluated in this study, to explore their potential for use as industrial raw materials. In total, 692 products were analyzed using standard analytical methods. The functional and pasting properties of the samples were found to vary significantly (p < 0.05). Toasted cassava was found to have the highest water absorption capacity, at 467.42 %, and dried cassava the lowest, at 252.57 %. Conversely, dried cassava was found to have the highest peak and breakdown viscosities, and toasted cassava the lowest. A significant (p < 0.01) positive correlation was found to exist between dispersibility and the swelling power (r = −0.93) and solubility index (r = −0.84) of the cassava products. Meanwhile, the correlation between dispersibility and the peak (r = −0.75) and breakdown (r = −0.72) viscosities was positive and significant (p < 0.05). Therefore, the authors of this study conclude that user industries such as the food, paper, adhesives, textiles and plywood sectors might require information on the pre-processing of cassava-based feedstock, so as to predetermine the technical usability of such raw materials within their industrial processes.