This work investigated the effect of yam flour substitution on characteristics of wheat bread and also determined the functional properties of the experimental flour samples. Flours were obtained from three varieties of yam (Dioscorea rotundata, Dioscorea alata and Dioscorea bulbifera) and blended with wheat flour at 25, 50 and 75 percent levels of substitution for bread production. Wheat flour (WF) and each of the yam flours were used as the positive and negative controls respectively. The functional properties (bulk density, water/oil absorption capacities, emulsion activity) of the flour samples were determined while the proximate, physical and sensory characteristics of loaves were also determined. The functional properties of the flour samples ranged from 0.42 g/ml to 0.67 g/ml packed bulk density; 0.39 g/ml to 0.47 g/ml loose bulk density; 0.88 ml/g to 2.10 ml/g oil absorption capacity; 1.50 ml/g to 3.90 ml/g water absorption capacity and 43.75% to 49.37% emulsion activity. The proximate composition of the bread samples ranged from 26.82% to 38.90% moisture, 4.23% to 5.10% fat, 6.10% to 9.25% protein, 1.90% to 2.45% ash, 0.12% to 0.64% crude fiber and 46.43% to 56.71% carbohydrate. The volume, weight and specific volume of loaves varied from 200 ml to 400 ml, 142.6 g to 170.2 g and 1.18 ml/g to 2.81 ml/g respectively. The crack formation of bread samples showed that there were no cracks on wheat bread (WF) and 25% yam flour substituted breads while 100 percent yam flour breads had large cracks. The sensory properties of the 25% yam flour substituted breads were statistically (p40.05) the same with the 100% wheat bread but differed from all the other bread samples. The mean score of the sensory attributes decreased as yam flour increased in the formulation. Sensory Evaluation of the bread samples showed that substitution level of 25% yam flour produced bread that was acceptable to the consumers whereas up to 50% and above were not acceptable. It is therefore recommended that substitution level of not more than 25% yam flour be used for yam/wheat composite bread production. & 2015 The Authors. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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Fish is a rich source of several important nutrients and an important part of the otherwise plant-dominated diet present in Angola. However, fish may also be a source of contaminants. The aim of this study was to analyse the nutrient contents and the levels of chemical contaminants, including arsenic, cadmium, mercury, and lead, in five commonly consumed marine fish species sampled during a survey with the research vessel Dr. Fridtjof Nansen in Angola. The species’ contribution to recommended nutrient intakes (RNI) for women and children was assessed and compared to that of food products of terrestrial animal origin. All the sampled species are good sources of protein and micronutrients if included in the diet, and inter-species variation is evident. The species were identified to contribute 5–15% of the RNI for calcium, iron, iodine, and zinc and exceeded the contribution to protein and iron intakes of food products of terrestrial animal origin. Furthermore, the potential consumer exposure to chemical contaminants in the species was assessed. None of the species exceeded the maximum levels for cadmium, mercury, and lead, and the potential consumer exposure to cadmium and methylmercury was considered low. The data presented in this study represent an important contribution to African food composition tables.

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