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Lund University (2015)

Chemical analysis to promote the use of wild fruits from Mozambique

Magaia, Telma

Titre : Chemical analysis to promote the use of wild fruits from Mozambique

Auteur : Magaia, Telma

Université de soutenance : Lund University


Wild fruit trees have significant cultural and socio-economic value in rural areas of Mozambique. Most of the wild fruits are seasonal and are available mainly in the wet season. Generally they have a short shelf-life and are eaten fresh or after minimal processing ; the most common method of preservation is sun-drying. The fruits of Adansonia digitata, Landolphia kirkii, Salacia kraussii, Sclerocarya birrea, and Vangueria infausta were selected for this study.New data on nutritional components and other characteristics have been obtained. The pH, titratable acidity and the content of soluble solids in the fruit pulps were determined. The organic acids citric, malic and succinic acids were found at various amounts in all pulps. The contents of different mono- and disaccharides were also analysed in the pulps. The protein content was low in all the fruit pulps, as is the case in fruits in general. However, the protein content was h igh in the k ernels o f A. digitata and S. birrea, about 30 to 40% on d ry matter b asis. The total content and relative amounts of the different essential amino acids are with a few exceptions similar to or above that recommended by the WHO for children aged 3 to10 years. The fat content was below 2% in the fruit pulps, while the fat content in A. digitata kernels was almost 40%, and S. birrea kernels about 60%. The kernels of A. digitata and S. birrea are rich in unsaturated fatty acids, and constituted about 68 and 80%, respectively, of the total fat. The A. digitata kernels contained appreciable amounts of essential fatty acids ; the amount of linoleic was about 30% and linolenic acid 2%. S. birrea kernels contained about 7% linoleic acid. The fruits contained both insoluble and soluble dietary fibre. The pulp of A. digitata had the highest amount of soluble dietary fibre, around 60% (on dry matter basis), while V. infausta pulp had the highest amount of insoluble dietary fibre, around 40%. The kernels contained 3 to 5% phytic acid which may decrease the absorption of minerals. Treatment with phytase reduced the phytic acid content by 20 to 30% after only 15 minutes enzymatic incubation. Interestingly, a lmost 50% o f the e stimated o riginal content of minerals was found in the supernatant after a few minutes enzyme incubation. The amount of iron in the pulps ranged from 1 to 9 mg/100 g (on dry matter basis) ; the highest amount being observed in S. kraussii. The highest iron content, 29 g/100 g DM, was found in whole seeds of A. digitata, 29 mg iron/100 g. The A. digitata pulp contained an appreciable amount of calcium, and the kernel also had high content of calcium. In conclusion, data from this study can be used to encourage the increased consumption of these wild fruits and kernels. In addition, the results of the analysis of the investigated fruits can form the basis for the selection of fruits for wider use, domestication, and processing to extend their shelf-life and for the manufacture of other food products.

Mots clés : pulps, kernels, consumption, fat, protein, minerals, dietary fibre


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Page publiée le 24 décembre 2015, mise à jour le 11 mars 2019