Optimization of Walnut Oil Nanoemulsions Prepared Using Ultrasonic Emulsification: A Response Surface Method

Abstract

Response surface methodology-central composite rotatable design (RSM-CCRD) was applied to determine effects of ultrasonic time (UT, 5–15 minutes), walnut oil (WO, 4–10% w/w) content, and concentration ratio of Span 80 to Tween 80 (K ₀, 0.55–0.80), on the some physicochemical characteristics of WO/water nanoemulsion including average particle size, Span and loss of antioxidant activity (LAA). Analysis of variance (ANOVA) showed that second-order polynomial models with high R ² (0.944–0.983) were well adjusted to predict response variables. The linear effect of UT was found to be most significant in all response surface models. The optimal conditions were: UT of 5.0 minutes, WO content of 7.35% w/w, and K ₀ of 0.8. Under these conditions, the average particle size, Span, and LAA were 356.08 nm, 0.548%, and 10.96. The adequacy of the models was confirmed by production this nanoemulsion under optimum values given by the model.

Keywords:

• Nanoemulsion
• particle size distribution
• polydispersity index
• response surface methodology (RSM)
• ultrasound
• walnut oil

Notes

^a UT.

^b WO content.

^c Concentration ratio of Span 80 to Tween 80.

^d Coded value.

^e Actual value.

Y ₀: Experimental date.

Y _i: Predicted value.

Y ₀ – Y _i: Residue.

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