Table 1.
Coded levels of independent variables used in response surface methodology (RSM).
Table 2.
Total vitamin E (tocopherols and tocotrienols) content of RPO and other vegetable oils.
Fig 1.
The effect of homogenization pressure and cycle on droplet size of nanoemulsion at 20 wt% of red palm oil (RPO), 5wt% of surfactant (Tween 80 only), 10 wt% of glycerol and 65wt% water (n = 3).
Table 3.
The effect of 5 wt% and10 wt% mixed surfactant with different hydrophilic-lipophilic balance (HLB) value on droplet.
Fig 2.
The effect of 5 wt% and 10 wt% of mixed surfactant (HLB 11& 14) on droplet size at 25°C storage temperature.
The nanoemulsions were prepared at 20 wt% oil, 10 wt% glycerol, 60–65 wt% water, while 5 wt% and 10 wt% total mixed surfactant, at the homogenization pressure and cycle of 600 bar and 4 cycles, respectively.
Fig 3.
Normal probability plot residual for droplet size (A) & polydispersity index (B).
Table 4.
Matrix of the central composite design (CCD) in coded levels, actualvalue and predicted value.
Table 5.
Analysis of variance of the regression coefficients of the quadratic equations for droplet size and polydispersity index (PDI) of red palm oil (RPO) nanoemulsion.
Fig 4.
Effect of surfactant concentration, glycerol concentration in aqueous phase and homogenization pressure on droplet size of red palm oil (RPO) nanoemulsion.
Response surface plot showing the effect of (A) 10 wt% of surfactant concentration and 20 wt% of glycerol concentration, (B) 10 wt% of surfactant concentration and 600 bar homogenization pressure, (C) 20 wt% of glycerol concentration and 600 bar homogenization pressure, on droplet size of red palm oil (RPO) nanoemulsion, missing independent variable in each figure was kept at the centre point.
Fig 5.
Effect of surfactant concentration, glycerol concentration in aqueous phase and homogenization pressure on polydispersity index of red palm oil (RPO) nanoemulsion.
Response surface plot showing the effect of (A) 10 wt% of surfactant concentration and 20 wt% of glycerol concentration, (B) 10 wt% of surfactant concentration and 600 bar homogenization pressure, (C) 20 wt% of glycerol concentration and 600 bar homogenization pressure, on polydispersity index (PDI) of red palm oil (RPO) nanoemulsion, missing independent variable in each figure was kept at the centre point.
Table 6.
Comparison predicted value and observed value for droplet size and polydispersity index of red palm oil (RPO) nanoemulsion concentration.
Fig 6.
TEM image of red palm oil-in-water nanoemulsions.
Scale bar represents 200nm.