Development of Morinda citrifolia citrus-flavoured drinks using Response Surface Methodology (RSM)

A central composite design (CCD) was applied to study the response pattern for monitoring flavour acceptability and physico-chemical properties of Morinda citrifolia drinks in product formulation study. Response Surface Methodology (RSM) involving sensory evaluation with hedonic rating scale was used to obtain the best ratio of Morinda to calamansi juice. The level of calamansi juice added significantly influenced (p 0.05) the degree of liking for aroma, colour, sourness, sweetness and overall acceptability as well as the level of pH, colour index L*, a*, b* and viscosity. The sensory scores for aroma, colour and overall acceptability were increased as the percentage of calamansi juice increased. Both factors, however, were not significantly correlated to the other responses of acidity (%) and total soluble solids (°Brix). The optimum formulation of Morinda citrus-flavoured drink can be predicted from the regression equation obtained in this investigation. The RSM results indicated that high levels of Morinda juice (20%) produced optimum acceptance of aroma, colour, sourness, sweetness and overall acceptability, but calamansi juice incorporation must be kept at 8.81%. The pH, total soluble solids, total acidity and viscosity for the optimum formulation was 3.26, 11.35 °Brix, 0.47% (expressed as citric acid) and 98.43 mPa.s, respectively.