Biochemical and antioxidant properties of cream and orange-fleshed sweet potato

Growing location and root maturity impact on the phenolic compounds, antioxidant activity and nutritional profile of different sweet potato genotypes

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Undersized roots had high content of phenolic compounds and antioxidant activity.

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The agro-ecological region affected the phenolic contents of sweet potatoes.

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Chlorogenic and 3,5-dicaffeoylquinic acids were the main phenolic compounds.

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Orange-fleshed cultivars had high concentrations of total carotenoids and β-carotene

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The protein content in the orange-fleshed cultivars was higher than in the others.

This study aimed to analyze the phenolic compounds, antioxidant activity, and the main nutritional components of different colored-fleshed sweet potato genotypes grown in Argentina. Three cultivars of standard size were compared to undersized ones, currently discarded. Furthermore, four genotypes grown in different agroecological locations in Tucuman, Argentina, were evaluated. Chlorogenic and 3,5-dicaffeoylquinic acids were identified as the prevailing phenolic compounds in all samples. Undersized roots had significantly higher phenolics, antioxidant activity and carotenoids than standard. Therefore, they can confer healthy attributes to processed foods and, additionally, reduce waste. Genotypes from Tucuman grown under water stress conditions presented the lowest phenolics, anthocyanins and antioxidant activity, but the highest carotenoid contents. Orange-fleshed cultivars showed the highest protein percentages (6.0–11.7 %) and carotenoid contents ranging between 310 and 1012 µg β-carotene/g dw, with more than 90 % β-carotene. These findings could help to promote the cultivation of local genotypes with high added value.

Rheological behaviour, physical and sensory properties of orange fleshed sweet potato and soy concentrate bread

Trends on the use of non-wheat flours for bread production has led to researches on improving the rheological characteristics of such non-wheat flours. This aim of this study was to determine the effect of soy concentrate on the protein and rheological behaviour (pasting and mixolab) of the orange-fleshed sweet potato composite flour as well as the physical and sensory qualities of the bread produced. The experimental design to obtain the optimum blends was carried out using optimum design of response surface methodology; with sweat potato, soy bean concentrate, date palm flour and potato starch as the independent variables. The result shows that protein values ranged from 6.19 to 21.10%, carotenoid values ranged from 0.11 to 26.18 mg/100 g. pasting temperature ranged from 68.50 to 82.33 °C; peak viscosity ranged between 159 and 1040 RVU, the breakdown value ranged between 24 and 272 RVU and the setback value ranged from 75 to 368 RVU. The bread loaf weights ranged from 111 to 256 g and the specific loaf volume ranged from 0.7 to 1.6cm³/g. The bread samples varied significantly (p < 0.05)  with the consumer's acceptability in terms of aroma, appearance, taste and overall acceptability. It was observed that soy-concentrate increase the protein content and improves rheological properties of the composite flour for the production of gluten free bread.