Abstract In this paper, the loss of L-ascorbic acid, thiamine and riboflavin in rosehip nectar with the heating periods (0, 5, 10, 15, 20 and 30 min) at temperatures ranging from 70 to 95 °C is analyzed and experimental results are presented. Firstly, dried rosehip fruits were processed to rosehip nectar and then thermal treatment is performed. Liquid chromatographic (HPLC) method was used for the analysis of the contents of L-ascorbic acid, thiamine and riboflavin and examined compounds are thoroughly separated within 25 min. During thermal processing, degradation of L-ascorbic acid, thiamine and riboflavin in rosehip nectar were fitted to a first-order reaction kinetic model. Arrhenius relationship was used for the description of temperature dependence of reaction. Activation energies for L-ascorbic acid, thiamine and riboflavin between 70 to 95 ºC were found to be 55.30, 36.38 and 37.15 kJ/mol, respectively. To the best of the author’s knowledge, due to lack of study on the thermal degradation of L-ascorbic acid, thiamine and riboflavin in rosehip nectar, this manuscript will be the first reported study to enable future analysis.

Abstract This research examines the effect of adding olive leaf on the yield and quality of the olive oil extracted from malaxation and ultrasound application during the olive oil extraction process. The olive variety Ayvalık was used in the trials, which included leaf addition of 2% and 5% and ultrasound application of 5, 10, 15, 20, 25, 30, 35, and 40 minutes (min). Several values, such as maturity index and oil yield, as well as olive oil parameters, including free acidity, peroxide value, oxidative stability, and specific ultraviolet absorption, were analyzed and examined. We also carried out sensory analyses on the extracted olive oils. The results show that the product extracted has no sensory defects and exhibits a fruitiness level greater than 0. The research showed that, in terms of yield and quality, a time span of 15 min with addition of 2% olive leaf would provide optimum conditions in ultrasound assisted olive oil extraction with olive leaf addition. The olive oils produced in this process fall into the category of “extra virgin olive oil”.