Effect of Pasteurisation on the Proximate Composition, Mineral and Sensory Properties of Fresh and Dry Tiger Nuts, and Their Milk Extracts

Abstract

The proximate, mineral and sensory properties of pasteurised and unpasteurised fresh and dry yellow tiger nuts and their milk extract were evaluated. Milk from samples of fresh and dry tiger nuts were extracted separately by wet milling and expression before pasteurisation. The moisture, protein, fat, ash, crude fibre, carbohydrate and energy content of the tiger nuts varied from 14.36 – 47.98%, 5.54 – 6.85%, 1.31 – 1.97%, 5.28 – 4.60%, 26.09 – 24.60%, and 296.72 – 434.00 KJ/g respectively. The total sugar content was 9.82 – 11.85% for pasteurised tiger nuts and 10.09 – 12.64% for unpasteurised nuts while reducing sugar ranged from 3.06 – 4.82 and 3.67 – 5.01% respectively, for pasteurised and unpasteurised tiger nuts. Cu, Fe, Zn, Ca, Mg and K content ranged from 0.09 – 0.13, 11.00 – 13.74, 0.05 – 0.06, 1692.94 – 1921.99, 265.12 – 794.57 and 1048.34 – 1181.67 mg/100g respectively. The moisture, protein, fat, ash, crude fibre, carbohydrate and energy values of the milk extract varied from 76.93 – 81.92%, 9.84 – 11.41%, 3.09 – 5.01%, 0.01 – 0.03%, 0.01 – 0.11%, 2.74 – 7.16% and 373.22 – 488.68 KJ/g respectively. Total sugar content was 9.63 – 11.64 and 10.81– 12.23% respectively, for the pasteurized and unpasteurized milk while the reducing sugar ranged from 3.42 – 4.13 and 4.14 – 4.49 %. Cu, Fe, Zn, Ca, Mg and K content varied from 0.02 – 0.03, 3.67 – 4.34, 0.02 – 0.03, 606.98 – 669.32, 86.88 – 289.71 and 349.45 – 393.89 mg/100g respectively. Dry tiger nut and its milk had significantly (P≤0.05) higher proximate, sugar and mineral contents. Pasteurization significantly (P<0.05) increased the ash, moisture, carbohydrate, Cu, Fe and Mg with decrease in fat, protein and sugar contents of the milk. This study has revealed that pasteurization contributed to significant increase in nutrient content of the tiger nuts and its milk.