Enrichment of Hazelnut Oil with Several Polyphenols: An Alternative Approach to A New Functional Food

Hazelnut oil has been examined according to its oxidative stability and antioxidant activity. The oil sample has been treated with gallic acid, ascorbic acid, catechin, vanillic acid, p-coumaric acid and rutin. Stability of the pure and treated oils against the oxidation has been assessed via Rancimat by detecting the protection factor. The quality parameters of the oil samples were compared depending on their antioxidant activity. D-Optimal design of Response Surface Method has been applied to optimize the enrichment conditions of hazelnut oil with several polyphenols. Principal component analysis has been applied to comprehend the relationship between the groups and their quality parameters. Depending on the analysis of variance test, the most important parameter (at p < 0.0001) affecting the relevant system has been found polyphenol type with respect to stability and antioxidant capacity. Gallic acid has enhanced the stability of hazelnut oil against oxidation ~3 times over that of pure sample. The maximum yields of protection factor, antioxidant activity and dissolved polyphenol level have been 2.738, 46.14% and 259.424 ppm under the optimum conditions (300 ppm gallic acid).