Improvement of shelf life and qualitative properties of fermented doughnut by antioxidant extracted from Salvia leriifolia compared to commercial antioxidant

Now a day antioxidants are widely used in foods to reduce the rate of oil oxidation reaction and researchers looking for potent antioxidants by less toxicity and greater efficacy. Plants are one of the best sources of natural antioxidants. Therefore, the aim of this study was to investigated the effect of adding different levels of alcoholic extract of Salvia leriifolia (0, 1, 2 and 3%) as a natural preservative to improvement storage time of fermented doughnut compared to TBHQ as commercial antioxidant on the physicochemical, textural and sensory properties of the final product in a completely randomized design (P˂0.05). The results showed that increasing the level of Salvia leriifolia extract from 0 to 3% had no effect on moisture content, specific volume, porosity and firmness of the final product (evaluated in three times of 2 h, 4 and 7 days after baking). However, by increasing the amount of this extract in fermented doughnut formulation, the peroxide index compared to other sample and the amount of total phenolic content, the antioxidant activity by DPPH method and the oxidative stability index at 2h, 4 and 7 days after baking were decreased and increased, respectively. On the other hand, the results showed that addition of Salvia leriifolia extract at different levels had no effect on the sensory properties of the final product. The results also indicated that the antioxidant activity of the sample containing 3% of Salvia leriifolia extract had the ability to compete with fried doughnut in oil containing synthetic antioxidant TBHQ. Therefore, the sample containing 3% of Salvia leriifolia extract was selected as the best sample because it had high antioxidant resistance, secondly, the addition of this extract had no adverse effect on physicochemical and sensory properties of the final product.