Effect of extrusion on the functional properties of carrot pulp added extrudates and in-vitro bioaccessibility of lutein and beta-carotene

Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Faculty of Engineering, Department of Food Engineering, Turkey

Approval Date: 2014

Thesis Language: English


Principal Supervisor (For Co-Supervisor Theses): İlkay Şensoy

Co-Supervisor: Zümrüt Ögel


In this study, effects of extrusion on the functional properties of carrot pulp added extrudates was investigated. Extrusion was performed at four different conditions. Two different temperature profile and two different screw speeds were investigated. Change in antioxidant activity, phenolic content, β-carotene and lutein content and their in-vitro bioaccessibilities after extrusion were investigated. Antioxidant activity and total phenolic content was determined by DPPH and Folin–Ciocalteu method, respectively. It was found that extrusion process significantly decreased (p≤0.05) the level of both the antioxidant activity and the total phenolic content, but the extrusion temperature and the shear rate did not cause a significant change (p>0.05) within the ranges studied. Effect of conventional heating process on antioxidant activity and phenolic content was also investigated, where no significant changes were observed (p>0.05). The quantification of carotenoids was conducted with HPLC. It is investigated that extrusion process resulted in the loss of β-carotene and lutein content at specified conditions. Extrusion process at 130°C last zone temperature did not affect the lutein in-vitro bioaccessibility while increased the in-vitro bioaccessibility at 160°C (p≤0.05). In-vitro bioaccessibility of β-carotene increased after extrusion both at 130°C and 160°C last treatment zone temperatures