Journal of Agricultural Science and Food Research

Journal of Agricultural Science and Food Research
Open Access

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Abstract

Effect of Fermentation and Boiling on Functional and Physico Chemical Properties of Yam and Cassava Flours

Kasaye T, Melese A, Amare G and Hailaye G

Cassava and yam are a source of food security, not only because it can be grown on less productive land, but
because it is a source of income for producers and generally a low cost source of food. Hence, the present tubers
were cultivated new region of Ethiopia which is not cultivated yet. This work aims at examining the physical,
chemical and functional properties of flour produced from cassava and yam tubers collected from Shewa Robit
integrated research and development site of Debre Berhan University, North Shewa Administrative Zone,
Shewarobit, Ethiopia. The flours were produced using fermentation and boiling processing methods. Flours
produces were subjected to physio-chemical and functional properties analyses. The tubers were washed, sorted,
peeled and sliced. The sliced tubers were divided into two portions. One portion was fermented for 72 hr. The other
portion was boiled for about 45 minutes. Both prepared samples were dried using sun. The moisture contents of the
samples were 9.51% for cassava and 12.46% for yam for raw samples. Based on dry weight basis, the ash, crude
fat, protein and crude fiber were 2.47, 1.12, 1.02 and 4.09%, respectively, for the raw sample of cassava and 3.81,
0.69, 6.98, and 3.77% for the raw sample of yam. The mineral contents of the samples were 734.88, 639.71 mg/kg
Ca, 30.38, 51.52 mg/kg Fe, and 4.7, 15.93 mg/kg Zn content in raw cassava and yam samples, respectively. Among
the anti-nutritional factors analyzed, the level of cyanide, phytate and oxalate were determined to be 36.2, 809.48
and 2.32 mg/1000 g in raw cassava sample respectively and the level of tannin and oxalate 1036.0 and 14.03 mg/kg
in raw yam sample respectively. Both cyanide and phytate were not detected in raw yam samples and also in raw
cassava tannin is not detected. A reduction of 98.23%, 37.4% and 4.31% in the level of cyanide, phytate, and
oxalate was achieved by boiling process respectively and fermentation brought about 100%, 48.5% and 31.9%, in
the level of cyanide, phytate and oxalates in cassava samples. Tannin and oxalate were reduced by 69.2% and
30.8% by boiling and 70.7% and 69.13% reduction was achieved by fermentation for yam samples. The bulk
density, water absorption capacity, oil absorption capacity, foaming capacity and foam stability were within the range
of 0.65-0.86 g/ml, 0.65-0.86 ml/g, 0.8-1.24 ml/g, 2.55-3.25% and 2.25-2.56% for cassava flour and 0.64-0.97 g/ml,
0.64 to 1.12 ml/g, 0.55-0.87 ml/g, 3.26-3.56% and 0.87-2.45% for yam flour samples, respectively. Natural
fermentation has resulted in reduction in all types of anti-nutrients for both cassava and yam samples, particularly,
cyanide. Fermented cassava and yam flours will have a good potential for product development.

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