Nadjiam DjirabayeChadian Institute of Agronomic Research for Development - ITRAD, Chad
Title: Physicochemical Characterization of Nine Cassava (Manihot esculenta Crantz) Cultivars from Chad
In Chad, despite the multiple culinary uses of cassava leaves and tubers, their nutritional values are untapped. In this study, the physicochemical compositions and structure of nine cultivars were assessed. The proteins were obtained by Kjeldahl’s method. Total sugars were determined according to the Luff-Schoorl method. For starch content, the polarimetric method of Earle and Milner was used. Mineral elements were carried out using an atomic absorption spectrophotometry. The cyanide was evaluated by the method of Williams and Edwards. Significant variability has been demonstrated in the leaves and dry tubers except for water content and dry matter. Analysis of the variances of the components of the tubers reveals that the water contents of the cultivars vary from 5.01% to 5.86%. The ash contents vary from 4.23% (cultivar DVA2) to 8.32% (cultivar DVL2). For total sugars, the values are between 53.63% (cultivar DVL2) and 57.99% (cultivars DVL12 and KA0303). The fiber contents are lower and vary from 1.74% (cultivar DVL12) to 1.92% (cultivars SB1366, DVA2, TL0101 and PG1314). The starch content varies from 28.93% (cultivar DVL12) to 31.05% (cultivar SB1366). The variations in mineral constituents of the tubers in mg/100g are Ca (145.21 - 250.08), Mg (83.89 - 165.22), P (147.34 - 360.78), K (1534.50 - 3064.09), Zn (0.75 - 0.82) and Mn (0.78 - 0.89). Iron concentrations are from 7.72 mg/100g (cultivar BA0909) to 60.62 mg/100g (cultivar DVA2). Analysis of the variances of the leaf constituents reveals high contents of Calcium for SB1366 (2108.41 mg/100g), of iron (Fe 54.26 mg/100g) and potassium (K 1866.86 mg/100g) for DVL12, of phosphorus for TL0101 (471.87 mg/100g), of phosphorus (470.36 mg/100g) and protein (30.74%) for PG1314, for magnesium for DVA2 (383.41 mg/100g) and Copper for KA0303 (0.0147 mg/100g). The concentrations of hydrocyanic acids are high in both leaves than fresh tubers (85 - 150 ppm). Lowest values are observed in tubers (10 - 15 ppm) for cultivar DVA2. Principal component analysis of the physicochemical characteristics of the leaves revealed four groups: the first very rich in calcium, magnesium and average potassium contents. Groups 2 and 3 are poor in calcium and magnesium but Group 2 has the highest potassium content while Group 3 has an intermediate content. Group 4 is very rich in calcium but low in magnesium and potassium. According to tubers, three groups have been identified which are characterized by low, intermediate and high contents in phosphorus. Cultivars SB1366, DVA2, DVL2, TL0101 and PG1314 show promising nutritional values and chemical constituents even if some have high levels of hydrocyanic acids.
In conclusion, a significant variability of the physicochemical constituents was demonstrated at the level of the leaves and tubers. The concentrations of different minerals vary depending on the cultivar. The significant differences observed between cultivars testify to their richness in nutrients. The determination of the potential hydrogen cyanide identified cultivars that need to be detoxified before human consumption.
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