Rosemary and Oregano Essential Oils as Natural Antioxidant to Preserve Pistachio Puree

In this study, the effect of adding essential oil from different plants on prolonging the shelf life of pistachio puree was investigated. For this purpose, Rancimat method, which is one of the accelerated shelf-life test (ASLT) methods, was used to determine the effect of oregano (OO) and rosemary (RO) essential oils on the oxidative stability of pistachio puree. Butylated hydroxyanisole (BHA) and the control sample were used for the comparison. Concentrations used for essential oils and synthetic antioxidants were 150, 300 and 600 ppm and 150 ppm, respectively. The conductivity was followed at three temperatures, 110, 120 and 130 °C, with the addition of essential oils and BHA to pistachio puree during ASLT. Pistachio puree with essential oils showed protection against the lipid oxidation process. As the temperature increased induction time was significantly decreased during ASLT (p < 0.05). The same concentrations of essential oils and BHA were also added into pistachio puree to observe the change in peroxide value (PV) and free fatty acid (FFA) value under normal storage temperatures 15, 25 and 40 °C. The PV and FFA increase were lower in RO, OO and BHA added pistachio puree samples during 8-month storage (p < 0.05). Six hundred (600) ppm of RO added sample had an antioxidative effect as much as 150 ppm BHA added sample for both ASLT and normal storage conditions. These essential oils could be used as natural antioxidants in foods with high lipid content increasing the shelf life of these products.