Abstract

The effect of moisture content variation on the characteristics and oil yield of tiger nut (Cyperus esculentus) seeds was investigated. The oil was extracted using the Soxhlet method at 9.5%, 20%, 30% and 40% moisture content for sample A, B, C and D respectively. The extracted oil was characterized using standard methods. The result showed a percentage oil yield of 25.89%, 19.05%, 12.48% and 12.14% for sample A, B, C and D respectively. The viscosity (mm2/s), specific gravity and smoke point ranges from 0.53-2.27, 0.91-0.84, and 231-215 respectively. The saponification value (mg/KOH/g), iodine value (g/100g) and acid value (mg/KOH/g) are 143.06, 185.13, 260.87, 294.52; 72.00, 88.45, 85.60, 88.45 and 3.37, 30.86, 65.90, 71.81 for sample A, B, C and D respectively. The peroxide value (m/mol/kg) and free fatty acid (mg/KOH/g) ranges from 2-21 and 6.73-143.62 respectively for the extracted oil at moisture content range of 9.5- 40%. Moisture content has no effect on the refractive index of tiger nut oil; the high free fatty acid value indicates its edibility. It can be concluded that oil yield decreases with increase in moisture content, with the highest oil yield obtained at 9.5% moisture content. Therefore, an initial seed moisture content of 9.5% is recommended for the extraction of oil to obtain maximum oil yield. The oil can be use as lubricant, cooking as substitute for other vegetable oil and good for soap making.

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