Modelling of Milk Solids Extraction from Tigernut ( Cyperus Esculentus L) Tubers Using Response Surface Methodology

Vegetable milk solids from black and brown varieties of tiger nut ( Cyperus esculentus L) tubers were extracted using water. Response surface methodology was used to determine the optimum conditions for extraction. The factors and their levels were boiling time (10.125, 240 minutes), milling time (5, 17.5, 30 minutes), and tuber: water (1: 2, 1:5, and 1: 8). The data obtained were fitted to second order polynomial models to enable the determination of variables for the estimation and prediction of the extraction of milk solids. The optimum extraction conditions were for the black cultivar; milling time, 23.8 minutes; tuber: water, 1 g: 7.8 ml; boiling time, 240 minutes and for the brown cultivar, milling time, 22.0 minutes; tuber: water, 1 g: 7.2 ml; boiling time, 10 minutes. Under the experimental conditions the expected milk solids for the black tubers was 65.07 (0.40) % against the predicted value of 70.66 % and that for the brown, 74.84 (1.84) % against the predicted value of 80.99 %.