2.9. The Stability Determination of Nanoemulsions

The nanoemulsions were stored at 4 °C for four weeks. The physical stability of the nanoemulsions was characterized at time intervals of one week. The physical stability was evaluated by measuring the change of MDD of nanoemulsions during the storage [23].

The measurement of TBARS (product of the reaction of thiobarbituric acid with malondialdehyde) was determined according to the method that was described by Nejadmansouri et al. [24]. The TBARS levels were established according to 1,1,3,3-tetraethoxypropane standard curve, being measured at 532 nm.

The nanoemulsion samples were heated in a boiling water bath for 10 min. and 30 min, cooled to room temperature, and then diluted 100 times with 10 mM pH 7.0 phosphate buffer solution to measure the MDD of the samples [25].

The nanoemulsion samples were stored in a refrigerator at −20 °C for 20 h and then thawed in a water bath at 35 °C for 2 h. The MDD of the samples were measured by diluting 100 times with 10 mM pH 7.0 phosphate buffer solution [26].